draft-ietf-taps-interface-06.txt   draft-ietf-taps-interface-07.txt 
TAPS Working Group B. Trammell, Ed. TAPS Working Group B. Trammell, Ed.
Internet-Draft Google Internet-Draft Google Switzerland GmbH
Intended status: Standards Track M. Welzl, Ed. Intended status: Standards Track M. Welzl, Ed.
Expires: 10 September 2020 University of Oslo Expires: 14 January 2021 University of Oslo
T. Enghardt T. Enghardt
TU Berlin Netflix
G. Fairhurst G. Fairhurst
University of Aberdeen University of Aberdeen
M. Kuehlewind M. Kuehlewind
Ericsson Ericsson
C. Perkins C. Perkins
University of Glasgow University of Glasgow
P. Tiesel P. Tiesel
TU Berlin TU Berlin
C. Wood C.A. Wood
Cloudflare
T. Pauly T. Pauly
Apple Inc. Apple Inc.
9 March 2020 13 July 2020
An Abstract Application Layer Interface to Transport Services An Abstract Application Layer Interface to Transport Services
draft-ietf-taps-interface-06 draft-ietf-taps-interface-07
Abstract Abstract
This document describes an abstract programming interface to the This document describes an abstract application programming
transport layer, following the Transport Services Architecture. It interface, API, to the transport layer, following the Transport
supports the asynchronous, atomic transmission of messages over Services Architecture. It supports the asynchronous, atomic
transport protocols and network paths dynamically selected at transmission of messages over transport protocols and network paths
runtime. It is intended to replace the traditional BSD sockets API dynamically selected at runtime. It is intended to replace the
as the lowest common denominator interface to the transport layer, in traditional BSD sockets API as the common interface to the transport
an environment where endpoints have multiple interfaces and potential layer, in an environment where endpoints could select from multiple
transport protocols to select from. interfaces and potential transport protocols.
Status of This Memo Status of This Memo
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This Internet-Draft will expire on 10 September 2020.
This Internet-Draft will expire on 14 January 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology and Notation . . . . . . . . . . . . . . . . . . 5 2. Terminology and Notation . . . . . . . . . . . . . . . . . . 5
3. Overview of Interface Design . . . . . . . . . . . . . . . . 6 3. Overview of Interface Design . . . . . . . . . . . . . . . . 7
4. API Summary . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. API Summary . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Usage Examples . . . . . . . . . . . . . . . . . . . . . 8 4.1. Usage Examples . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Server Example . . . . . . . . . . . . . . . . . . . 8 4.1.1. Server Example . . . . . . . . . . . . . . . . . . . 9
4.1.2. Client Example . . . . . . . . . . . . . . . . . . . 9 4.1.2. Client Example . . . . . . . . . . . . . . . . . . . 10
4.1.3. Peer Example . . . . . . . . . . . . . . . . . . . . 10 4.1.3. Peer Example . . . . . . . . . . . . . . . . . . . . 10
4.2. Transport Properties . . . . . . . . . . . . . . . . . . 11 4.2. Transport Properties . . . . . . . . . . . . . . . . . . 11
4.2.1. Transport Property Names . . . . . . . . . . . . . . 12 4.2.1. Transport Property Names . . . . . . . . . . . . . . 12
4.2.2. Transport Property Types . . . . . . . . . . . . . . 13 4.2.2. Transport Property Types . . . . . . . . . . . . . . 13
4.3. Scope of the Interface Definition . . . . . . . . . . . . 13 4.3. Scope of the Interface Definition . . . . . . . . . . . . 14
5. Pre-Establishment Phase . . . . . . . . . . . . . . . . . . . 14 5. Pre-Establishment Phase . . . . . . . . . . . . . . . . . . . 15
5.1. Specifying Endpoints . . . . . . . . . . . . . . . . . . 15 5.1. Specifying Endpoints . . . . . . . . . . . . . . . . . . 15
5.2. Specifying Transport Properties . . . . . . . . . . . . . 17 5.2. Specifying Transport Properties . . . . . . . . . . . . . 18
5.2.1. Reliable Data Transfer (Connection) . . . . . . . . . 19 5.2.1. Reliable Data Transfer (Connection) . . . . . . . . . 20
5.2.2. Preservation of Message Boundaries . . . . . . . . . 20 5.2.2. Preservation of Message Boundaries . . . . . . . . . 21
5.2.3. Configure Per-Message Reliability . . . . . . . . . . 20 5.2.3. Configure Per-Message Reliability . . . . . . . . . . 21
5.2.4. Preservation of Data Ordering . . . . . . . . . . . . 20 5.2.4. Preservation of Data Ordering . . . . . . . . . . . . 21
5.2.5. Use 0-RTT Session Establishment with an Idempotent 5.2.5. Use 0-RTT Session Establishment with a Safely
Message . . . . . . . . . . . . . . . . . . . . . . . 20 Replayable Message . . . . . . . . . . . . . . . . . 21
5.2.6. Multistream Connections in Group . . . . . . . . . . 21 5.2.6. Multistream Connections in Group . . . . . . . . . . 22
5.2.7. Full Checksum Coverage on Sending . . . . . . . . . . 21 5.2.7. Full Checksum Coverage on Sending . . . . . . . . . . 22
5.2.8. Full Checksum Coverage on Receiving . . . . . . . . . 21 5.2.8. Full Checksum Coverage on Receiving . . . . . . . . . 22
5.2.9. Congestion control . . . . . . . . . . . . . . . . . 22 5.2.9. Congestion control . . . . . . . . . . . . . . . . . 22
5.2.10. Interface Instance or Type . . . . . . . . . . . . . 22 5.2.10. Interface Instance or Type . . . . . . . . . . . . . 23
5.2.11. Provisioning Domain Instance or Type . . . . . . . . 23 5.2.11. Provisioning Domain Instance or Type . . . . . . . . 24
5.2.12. Use Temporary Local Address . . . . . . . . . . . . . 24 5.2.12. Use Temporary Local Address . . . . . . . . . . . . . 24
5.2.13. Parallel Use of Multiple Paths . . . . . . . . . . . 24 5.2.13. Multi-Paths Transport . . . . . . . . . . . . . . . . 25
5.2.14. Direction of communication . . . . . . . . . . . . . 25 5.2.14. Advertisement of Alternative Addresses . . . . . . . 26
5.2.15. Notification of excessive retransmissions . . . . . . 25 5.2.15. Direction of communication . . . . . . . . . . . . . 26
5.2.16. Notification of ICMP soft error message arrival . . . 25 5.2.16. Notification of excessive retransmissions . . . . . . 27
5.3. Specifying Security Parameters and Callbacks . . . . . . 26 5.2.17. Notification of ICMP soft error message arrival . . . 27
5.3.1. Pre-Connection Parameters . . . . . . . . . . . . . . 26 5.2.18. Initiating side is not the first to write . . . . . . 27
5.3.2. Connection Establishment Callbacks . . . . . . . . . 27 5.3. Specifying Security Parameters and Callbacks . . . . . . 28
6. Establishing Connections . . . . . . . . . . . . . . . . . . 28 5.3.1. Pre-Connection Parameters . . . . . . . . . . . . . . 28
6.1. Active Open: Initiate . . . . . . . . . . . . . . . . . . 28 5.3.2. Connection Establishment Callbacks . . . . . . . . . 29
6.2. Passive Open: Listen . . . . . . . . . . . . . . . . . . 29 6. Establishing Connections . . . . . . . . . . . . . . . . . . 30
6.3. Peer-to-Peer Establishment: Rendezvous . . . . . . . . . 30 6.1. Active Open: Initiate . . . . . . . . . . . . . . . . . . 30
6.4. Connection Groups . . . . . . . . . . . . . . . . . . . . 32 6.2. Passive Open: Listen . . . . . . . . . . . . . . . . . . 31
7. Sending Data . . . . . . . . . . . . . . . . . . . . . . . . 33 6.3. Peer-to-Peer Establishment: Rendezvous . . . . . . . . . 32
7.1. Basic Sending . . . . . . . . . . . . . . . . . . . . . . 34 6.4. Connection Groups . . . . . . . . . . . . . . . . . . . . 34
7.2. Sending Replies . . . . . . . . . . . . . . . . . . . . . 34 7. Sending Data . . . . . . . . . . . . . . . . . . . . . . . . 35
7.3. Send Events . . . . . . . . . . . . . . . . . . . . . . . 35 7.1. Basic Sending . . . . . . . . . . . . . . . . . . . . . . 36
7.3.1. Sent . . . . . . . . . . . . . . . . . . . . . . . . 35 7.2. Sending Replies . . . . . . . . . . . . . . . . . . . . . 36
7.3.2. Expired . . . . . . . . . . . . . . . . . . . . . . . 35 7.3. Send Events . . . . . . . . . . . . . . . . . . . . . . . 37
7.3.3. SendError . . . . . . . . . . . . . . . . . . . . . . 35 7.3.1. Sent . . . . . . . . . . . . . . . . . . . . . . . . 37
7.4. Message Contexts . . . . . . . . . . . . . . . . . . . . 36 7.3.2. Expired . . . . . . . . . . . . . . . . . . . . . . . 37
7.5. Message Properties . . . . . . . . . . . . . . . . . . . 36 7.3.3. SendError . . . . . . . . . . . . . . . . . . . . . . 38
7.5.1. Lifetime . . . . . . . . . . . . . . . . . . . . . . 37 7.4. Message Contexts . . . . . . . . . . . . . . . . . . . . 38
7.5.2. Priority . . . . . . . . . . . . . . . . . . . . . . 38 7.5. Message Properties . . . . . . . . . . . . . . . . . . . 38
7.5.3. Ordered . . . . . . . . . . . . . . . . . . . . . . . 38 7.5.1. Lifetime . . . . . . . . . . . . . . . . . . . . . . 40
7.5.4. Idempotent . . . . . . . . . . . . . . . . . . . . . 39 7.5.2. Priority . . . . . . . . . . . . . . . . . . . . . . 40
7.5.5. Final . . . . . . . . . . . . . . . . . . . . . . . . 39 7.5.3. Ordered . . . . . . . . . . . . . . . . . . . . . . . 40
7.5.6. Corruption Protection Length . . . . . . . . . . . . 40 7.5.4. Safely Replayable . . . . . . . . . . . . . . . . . . 41
7.5.7. Reliable Data Transfer (Message) . . . . . . . . . . 40 7.5.5. Final . . . . . . . . . . . . . . . . . . . . . . . . 41
7.5.8. Message Capacity Profile Override . . . . . . . . . . 40 7.5.6. Corruption Protection Length . . . . . . . . . . . . 42
7.5.9. Singular Transmission . . . . . . . . . . . . . . . . 40 7.5.7. Reliable Data Transfer (Message) . . . . . . . . . . 42
7.6. Partial Sends . . . . . . . . . . . . . . . . . . . . . . 41 7.5.8. Message Capacity Profile Override . . . . . . . . . . 43
7.7. Batching Sends . . . . . . . . . . . . . . . . . . . . . 42 7.5.9. No Fragmentation . . . . . . . . . . . . . . . . . . 43
7.8. Send on Active Open: InitiateWithSend . . . . . . . . . . 42 7.6. Partial Sends . . . . . . . . . . . . . . . . . . . . . . 43
8. Receiving Data . . . . . . . . . . . . . . . . . . . . . . . 42 7.7. Batching Sends . . . . . . . . . . . . . . . . . . . . . 44
8.1. Enqueuing Receives . . . . . . . . . . . . . . . . . . . 43 7.8. Send on Active Open: InitiateWithSend . . . . . . . . . . 44
8.2. Receive Events . . . . . . . . . . . . . . . . . . . . . 43 8. Receiving Data . . . . . . . . . . . . . . . . . . . . . . . 45
8.2.1. Received . . . . . . . . . . . . . . . . . . . . . . 44 8.1. Enqueuing Receives . . . . . . . . . . . . . . . . . . . 45
8.2.2. ReceivedPartial . . . . . . . . . . . . . . . . . . . 44 8.2. Receive Events . . . . . . . . . . . . . . . . . . . . . 46
8.2.3. ReceiveError . . . . . . . . . . . . . . . . . . . . 45 8.2.1. Received . . . . . . . . . . . . . . . . . . . . . . 46
8.3. Receive Message Properties . . . . . . . . . . . . . . . 45 8.2.2. ReceivedPartial . . . . . . . . . . . . . . . . . . . 46
8.3.1. UDP(-Lite)-specific Property: ECN . . . . . . . . . . 45 8.2.3. ReceiveError . . . . . . . . . . . . . . . . . . . . 47
8.3.2. Early Data . . . . . . . . . . . . . . . . . . . . . 45 8.3. Receive Message Properties . . . . . . . . . . . . . . . 48
8.3.3. Receiving Final Messages . . . . . . . . . . . . . . 46 8.3.1. UDP(-Lite)-specific Property: ECN . . . . . . . . . . 48
9. Message Framers . . . . . . . . . . . . . . . . . . . . . . . 46 8.3.2. Early Data . . . . . . . . . . . . . . . . . . . . . 48
9.1. Adding Message Framers to Connections . . . . . . . . . . 47 8.3.3. Receiving Final Messages . . . . . . . . . . . . . . 48
9.2. Framing Meta-Data . . . . . . . . . . . . . . . . . . . . 47
10. Managing Connections . . . . . . . . . . . . . . . . . . . . 48
10.1. Generic Connection Properties . . . . . . . . . . . . . 49
10.1.1. Retransmission Threshold Before Excessive
Retransmission Notification . . . . . . . . . . . . . 49
9. Message Framers . . . . . . . . . . . . . . . . . . . . . . . 49
9.1. Adding Message Framers to Connections . . . . . . . . . . 49
9.2. Framing Meta-Data . . . . . . . . . . . . . . . . . . . . 50
10. Managing Connections . . . . . . . . . . . . . . . . . . . . 50
10.1. Generic Connection Properties . . . . . . . . . . . . . 52
10.1.1. Retransmission Threshold Before Excessive
Retransmission Notification . . . . . . . . . . . . . 52
10.1.2. Required Minimum Corruption Protection Coverage for 10.1.2. Required Minimum Corruption Protection Coverage for
Receiving . . . . . . . . . . . . . . . . . . . . . . 50 Receiving . . . . . . . . . . . . . . . . . . . . . . 52
10.1.3. Priority (Connection) . . . . . . . . . . . . . . . 50 10.1.3. Priority (Connection) . . . . . . . . . . . . . . . 53
10.1.4. Timeout for Aborting Connection . . . . . . . . . . 50 10.1.4. Timeout for Aborting Connection . . . . . . . . . . 53
10.1.5. Connection Group Transmission Scheduler . . . . . . 51 10.1.5. Connection Group Transmission Scheduler . . . . . . 53
10.1.6. Capacity Profile . . . . . . . . . . . . . . . . . . 51 10.1.6. Capacity Profile . . . . . . . . . . . . . . . . . . 54
10.1.7. Bounds on Send or Receive Rate . . . . . . . . . . . 52 10.1.7. Policy for using Multi-Path Transports . . . . . . . 55
10.1.8. Read-only Connection Properties . . . . . . . . . . 53 10.1.8. Bounds on Send or Receive Rate . . . . . . . . . . . 56
10.2. TCP-specific Properties: User Timeout Option (UTO) . . . 54 10.1.9. Read-only Connection Properties . . . . . . . . . . 56
10.2.1. Advertised User Timeout . . . . . . . . . . . . . . 54 10.2. TCP-specific Properties: User Timeout Option (UTO) . . . 57
10.2.2. User Timeout Enabled . . . . . . . . . . . . . . . . 54 10.2.1. Advertised User Timeout . . . . . . . . . . . . . . 57
10.2.3. Timeout Changeable . . . . . . . . . . . . . . . . . 55 10.2.2. User Timeout Enabled . . . . . . . . . . . . . . . . 58
10.3. Connection Lifecycle Events . . . . . . . . . . . . . . 55 10.2.3. Timeout Changeable . . . . . . . . . . . . . . . . . 58
10.3.1. Soft Errors . . . . . . . . . . . . . . . . . . . . 55 10.3. Connection Lifecycle Events . . . . . . . . . . . . . . 58
10.3.2. Excessive retransmissions . . . . . . . . . . . . . 55 10.3.1. Soft Errors . . . . . . . . . . . . . . . . . . . . 58
11. Connection Termination . . . . . . . . . . . . . . . . . . . 55 10.3.2. Excessive retransmissions . . . . . . . . . . . . . 59
12. Connection State and Ordering of Operations and Events . . . 56 11. Connection Termination . . . . . . . . . . . . . . . . . . . 59
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 57 12. Connection State and Ordering of Operations and Events . . . 59
14. Security Considerations . . . . . . . . . . . . . . . . . . . 57 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 59 14. Security Considerations . . . . . . . . . . . . . . . . . . . 61
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 59 15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 62
16.1. Normative References . . . . . . . . . . . . . . . . . . 59 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 63
16.2. Informative References . . . . . . . . . . . . . . . . . 60 16.1. Normative References . . . . . . . . . . . . . . . . . . 63
Appendix A. Convenience Functions . . . . . . . . . . . . . . . 62 16.2. Informative References . . . . . . . . . . . . . . . . . 63
A.1. Adding Preference Properties . . . . . . . . . . . . . . 63 Appendix A. Convenience Functions . . . . . . . . . . . . . . . 66
A.2. Transport Property Profiles . . . . . . . . . . . . . . . 63 A.1. Adding Preference Properties . . . . . . . . . . . . . . 66
A.2.1. reliable-inorder-stream . . . . . . . . . . . . . . . 63 A.2. Transport Property Profiles . . . . . . . . . . . . . . . 67
A.2.2. reliable-message . . . . . . . . . . . . . . . . . . 64 A.2.1. reliable-inorder-stream . . . . . . . . . . . . . . . 67
A.2.3. unreliable-datagram . . . . . . . . . . . . . . . . . 64 A.2.2. reliable-message . . . . . . . . . . . . . . . . . . 67
A.2.3. unreliable-datagram . . . . . . . . . . . . . . . . . 68
Appendix B. Relationship to the Minimal Set of Transport Services Appendix B. Relationship to the Minimal Set of Transport Services
for End Systems . . . . . . . . . . . . . . . . . . . . . 65 for End Systems . . . . . . . . . . . . . . . . . . . . . 69
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 72
1. Introduction 1. Introduction
This document specifies a modern abstract programming interface atop This document specifies a modern abstract application programming
the high-level architecture for transport services defined in interface (API) atop the high-level architecture for transport
[I-D.ietf-taps-arch]. It supports the asynchronous, atomic services defined in [I-D.ietf-taps-arch]. It supports the
transmission of messages over transport protocols and network paths asynchronous, atomic transmission of messages over transport
dynamically selected at runtime. It is intended to replace the protocols and network paths dynamically selected at runtime. It is
traditional BSD sockets API as the lowest common denominator intended to replace the traditional BSD sockets API as the common
interface to the transport layer, in an environment where endpoints interface to the transport layer, in environments where endpoints
have multiple interfaces and potential transport protocols to select select from multiple interfaces and potential transport protocols.
from.
As applications adopt this interface, they will benefit from a wide As applications adopt this interface, they will benefit from a wide
set of transport features that can evolve over time, and ensure that set of transport features that can evolve over time, and ensure that
the system providing the interface can optimize its behavior based on the system providing the interface can optimize its behavior based on
the application requirements and network conditions, without the application requirements and network conditions, without
requiring changes to the applications. This flexibility enables requiring changes to the applications. This flexibility enables
faster deployment of new features and protocols. It can also support faster deployment of new features and protocols. It can also support
applications by offering racing and fallback mechanisms, which applications by offering racing and fallback mechanisms, which
otherwise need to be implemented in each application separately. otherwise need to be separately implemented in each application.
It derives specific path and protocol selection properties and It derives specific path and protocol selection properties and
supported transport features from the analysis provided in [RFC8095], supported transport features from the analysis provided in [RFC8095],
[I-D.ietf-taps-minset], and [I-D.ietf-taps-transport-security]. The [I-D.ietf-taps-minset], and [I-D.ietf-taps-transport-security]. The
design encourages implementations underneath the interface to design encourages implementations underneath the interface to
dynamically choose a transport protocol depending on an application's dynamically choose a transport protocol depending on an application's
choices rather than statically binding applications to a protocol at choices rather than statically binding applications to a protocol at
compile time. We note that transport system implementations SHOULD compile time. The transport system implementations should provide
provide applications a way to override transport selection and applications with a way to override transport selection and
instantiate a specific stack, e.g. to support servers wanting to instantiate a specific stack, e.g., to support servers wishing to
listen to a specific protocol. This specific transport stack choice listen to a specific protocol. This specific transport stack choice
is discouraged for general use, as it comes at the cost of reduced is discouraged for general use, because it can reduce the
portability. portability.
2. Terminology and Notation 2. Terminology and Notation
This API is described in terms of Objects, which an application can This API is described in terms of Objects with which an application
interact with; Actions the application can perform on these Objects; can interact; Actions the application can perform on these Objects;
Events, which an Object can send to an application asynchronously; Events, which an Object can send to an application asynchronously;
and Parameters associated with these Actions and Events. and Parameters associated with these Actions and Events.
The following notations, which can be combined, are used in this The following notations, which can be combined, are used in this
document: document:
* An Action creates an Object: * An Action creates an Object:
Object := Action() Object := Action()
skipping to change at page 6, line 11 skipping to change at page 6, line 25
* An Action takes a set of Parameters; an Event contains a set of * An Action takes a set of Parameters; an Event contains a set of
Parameters. Action and Event parameters whose names are suffixed Parameters. Action and Event parameters whose names are suffixed
with a question mark are optional. with a question mark are optional.
Action(param0, param1?, ...) / Event<param0, param1, ...> Action(param0, param1?, ...) / Event<param0, param1, ...>
Actions associated with no Object are Actions on the abstract Actions associated with no Object are Actions on the abstract
interface itself; they are equivalent to Actions on a per-application interface itself; they are equivalent to Actions on a per-application
global context. global context.
How these abstract concepts map into concrete implementations of this The way these abstract concepts map into concrete implementations of
API in a given language on a given platform is largely dependent on this API in a given language on a given platform largely depends on
the features of the language and the platform. Actions could be the features of the language and the platform. Actions could be
implemented as functions or method calls, for instance, and Events implemented as functions or method calls, for instance, and Events
could be implemented via event queues, handler functions or classes, could be implemented via event queues, handler functions or classes,
communicating sequential processes, or other asynchronous calling communicating sequential processes, or other asynchronous calling
conventions. conventions.
This specification treats Events and errors similarly. Errors, just This specification treats Events and errors similarly. Errors, just
as any other Events, may occur asynchronously in network as any other Events, may occur asynchronously in network
applications. However, it is recommended that implementations of applications. However, it is recommended that implementations of
this interface also return errors immediately, according to the error this interface also return errors immediately, according to the error
handling idioms of the implementation platform, for errors that can handling idioms of the implementation platform, for errors that can
be immediately detected, such as inconsistency in Transport be immediately detected, such as inconsistency in Transport
Properties. Errors can provide an optional reason to give the Properties. Errors can provide an optional reason to give the
application further details as to why the error occured. application further details as to why the error occurred.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Overview of Interface Design 3. Overview of Interface Design
The design of the interface specified in this document is based on a The design of the interface specified in this document is based on a
set of princples, themselves an elaboration on the architectural set of principles, themselves an elaboration on the architectural
design principles defined in [I-D.ietf-taps-arch]. The interface design principles defined in [I-D.ietf-taps-arch]. The interface
defined in this document provides: defined in this document provides:
* A single interface to a variety of transport protocols to be used * A single interface to a variety of transport protocols to be used
in a variety of application design patterns, independent of the in a variety of application design patterns, independent of the
properties of the application and the Protocol Stacks that will be properties of the application and the Protocol Stacks that will be
used at runtime, such that all common specialized features of used at runtime, such that all common specialized features of
these protocol stacks are made available to the application as these protocol stacks are made available to the application as
necessary in a transport-independent way, to enable applications necessary in a transport-independent way, to enable applications
written to a single API to make use of transport protocols in written to a single API to make use of transport protocols in
skipping to change at page 12, line 6 skipping to change at page 12, line 6
Connection.Close() Connection.Close()
4.2. Transport Properties 4.2. Transport Properties
Each application using the Transport Services Interface declares its Each application using the Transport Services Interface declares its
preferences for how the transport service should operate using preferences for how the transport service should operate using
properties at each stage of the lifetime of a connection using properties at each stage of the lifetime of a connection using
Transport Properties, as defined in [I-D.ietf-taps-arch]. Transport Properties, as defined in [I-D.ietf-taps-arch].
Transport Properties are divided into Selection, Connection, and Transport Properties are divided into Selection, Connection, and
Message Properties. During pre-establishment, Selection Properties Message Properties. Selection Properties (see The behavior of the
(see Section 5.2) are used to specify which paths and protocol stacks
can be used and are preferred by the application, and Connection
Properties (see Section 10.1) can be used to influence decisions made
during establishment and to fine-tune the eventually established
connection. These Connection Properties can also be used later, to
monitor and fine-tune established connections. The behavior of the
selected protocol stack(s) when sending Messages is controlled by selected protocol stack(s) when sending Messages is controlled by
Message Properties (see Section 7.5). Message Properties (see Section 5.2) can only be set during pre-
establishment. They are only used to specify which paths and
protocol stacks can be used and are preferred by the application.
Connection Properties (see Section 10.1) can also be set during pre-
establishment but may be changed later. They are used to inform
decisions made during establishment and to fine-tune the established
connection.Section 7.5).
All Transport Properties, regardless of the phase in which they are All Transport Properties, regardless of the phase in which they are
used, are organized within a single namespace. This enables setting used, are organized within a single namespace. This enables setting
them as defaults in earlier stages and querying them in later stages: them as defaults in earlier stages and querying them in later stages:
* Connection Properties can be set on Preconnections * Connection Properties can be set on Preconnections
* Message Properties can be set on Preconnections and Connections * Message Properties can be set on Preconnections, Connections and
Messages
* The effect of Selection Properties can be queried on Connections * The effect of Selection Properties can be queried on Connections
and Messages and Messages
Note that configuring Connection Properties and Message Properties on Note that configuring Connection Properties and Message Properties on
Preconnections is preferred over setting them later. Early Preconnections is preferred over setting them later. Early
specification of Connection Properties allows their use as additional specification of Connection Properties allows their use as additional
input to the selection process. Protocol Specific Properties, which input to the selection process. Protocol Specific Properties, which
enable configuration of specialized features of a specific protocol, enable configuration of specialized features of a specific protocol,
see Section 3.2 of [I-D.ietf-taps-arch], are not used as an input to see Section 3.2 of [I-D.ietf-taps-arch], are not used as an input to
the selection process but only support configuration if the the selection process but only support configuration if the
respective prototocol has been selected. respective protocol has been selected.
4.2.1. Transport Property Names 4.2.1. Transport Property Names
Transport Properties are referred to by property names. These names Transport Properties are referred to by property names. For the
are lower-case strings whereby words are separated by hyphens. These purposes of this document, these names are alphanumeric strings in
names serve two purposes: which words may be separated by hyphens. These names serve two
purposes:
* Allow different components of a TAPS implementation to pass * Allowing different components of a TAPS implementation to pass
Transport Properties, e.g., between a language frontend and a Transport Properties, e.g., between a language frontend and a
policy manager, or as a representation of properties retrieved policy manager, or as a representation of properties retrieved
from a file or other storage. from a file or other storage.
* Make code of different TAPS implementations look similar. * Making code of different TAPS implementations look similar. While
individual programming languages may preclude strict adherence to
the aforementioned naming convention (for instance, by prohibiting
the use of hyphens in symbols), users interacting with multiple
implementations will still benefit from the consistency resulting
from the use of visually similar symbols.
Transport Property Names are hierarchically organized in the form Transport Property Names are hierarchically organized in the form
[<Namespace>.]<PropertyName>. [<Namespace>.]<PropertyName>.
* The Namespace part MUST be empty for well-known, generic * The Namespace component MUST be empty for well-known, generic
properties, i.e., for properties that are not specific to a properties, i.e., for properties that are not specific to a
protocol and are defined in an RFC. protocol and are defined in an RFC.
* Protocol Specific Properties MUST use the protocol acronym as * Protocol Specific Properties MUST use the protocol acronym as
Namespace, e.g., "tcp" for TCP specific Transport Properties. For Namespace, e.g., "tcp" for TCP specific Transport Properties. For
IETF protocols, property names under these namespaces SHOULD be IETF protocols, property names under these namespaces SHOULD be
defined in an RFC. defined in an RFC.
* Vendor or implementation specific properties MUST use a string * Vendor or implementation specific properties MUST use a string
identifying the vendor or implementation as Namespace. identifying the vendor or implementation as Namespace.
Namespaces for the keywords provided in the IANA protocol numbers Namespaces for each of the keywords provided in the IANA protocol
registry (see https://www.iana.org/assignments/protocol-numbers/ numbers registry (see https://www.iana.org/assignments/protocol-
protocol-numbers.xhtml) are reserved for Protocol Specific Properties numbers/protocol-numbers.xhtml), reformatted where necessary to
and MUST not be used for vendor or implementation specific conform to an implementation's naming conventions, are reserved for
properties. Protocol Specific Properties and MUST not be used for vendor or
implementation-specific properties.
4.2.2. Transport Property Types 4.2.2. Transport Property Types
Transport Properties can have one of a set of data types: Transport Properties can have one of a set of data types:
* Boolean: can take the values "true" and "false"; representation is * Boolean: can take the values "true" and "false"; representation is
implementation-dependent. implementation-dependent.
* Integer: can take positive or negative numeric integer values; * Integer: can take positive or negative numeric integer values;
range and representation is implementation-dependent. range and representation is implementation-dependent.
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representation is implementation-dependent. representation is implementation-dependent.
* Enumeration: can take one value of a finite set of values, * Enumeration: can take one value of a finite set of values,
dependent on the property itself. The representation is dependent on the property itself. The representation is
implementation dependent; however, implementations MUST provide a implementation dependent; however, implementations MUST provide a
method for the application to determine the entire set of possible method for the application to determine the entire set of possible
values for each property. values for each property.
* Preference: can take one of five values (Prohibit, Avoid, Ignore, * Preference: can take one of five values (Prohibit, Avoid, Ignore,
Prefer, Require) for the level of preference of a given property Prefer, Require) for the level of preference of a given property
during protocol selection; see Section 5.2. during protocol selection; see Section 5.2. When querying, a
Preference is of type Boolean, with "true" indicating that the
Selection Property has been applied.
For types Integer and Numeric, special values can be defined per
property; it is up to implementations how these special values are
represented (e.g., by using -1 for an otherwise non-negative value).
4.3. Scope of the Interface Definition 4.3. Scope of the Interface Definition
This document defines a language- and platform-independent interface This document defines a language- and platform-independent interface
to a Transport Services system. Given the wide variety of languages to a Transport Services system. Given the wide variety of languages
and language conventions used to write applications that use the and language conventions used to write applications that use the
transport layer to connect to other applications over the Internet, transport layer to connect to other applications over the Internet,
this independence makes this interface necessarily abstract. this independence makes this interface necessarily abstract.
There is no interoperability benefit in tightly defining how the There is no interoperability benefit in tightly defining how the
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itself uses different names for substantially equivalent objects itself uses different names for substantially equivalent objects
for networking by convention. for networking by convention.
* Implementations of this interface SHOULD implement each Selection * Implementations of this interface SHOULD implement each Selection
Property, Connection Property, and Message Context Property Property, Connection Property, and Message Context Property
specified in this document. Each interface SHOULD be implemented specified in this document. Each interface SHOULD be implemented
even when this will always result in no operation, e.g. there is even when this will always result in no operation, e.g. there is
no action when the API specifies a Property that is not available no action when the API specifies a Property that is not available
in a transport protocol implemented on a specific platform. For in a transport protocol implemented on a specific platform. For
example, if TCP is the only underlying transport protocol, the example, if TCP is the only underlying transport protocol, the
Message Property "msg-ordered" can be implemented even if Message Property "msgOrdered" can be implemented even if disabling
disabling ordering will not have any effect TCP because the API ordering will not have any effect TCP because the API does not
does not guarantee out-of-order delivery. Similarly, the msg- guarantee out-of-order delivery. Similarly, the "msg-lifetime"
lifetime" Message Property can be implemented but ignored, as the Message Property can be implemented but ignored, as the
description of this Property states that "it is not guaranteed description of this Property states that "it is not guaranteed
that a Message will not be sent when its Lifetime has expired". that a Message will not be sent when its Lifetime has expired".
* Implementations may use other representations for Transport * Implementations may use other representations for Transport
Property Names, e.g., by providing constants, but should provide a Property Names, e.g., by providing constants, but should provide a
straight-forward mapping between their representation and the straight-forward mapping between their representation and the
property names specified here. property names specified here.
5. Pre-Establishment Phase 5. Pre-Establishment Phase
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preconfigured Connection Properties (Section 10.1), and the security preconfigured Connection Properties (Section 10.1), and the security
parameters (see Section 5.3): parameters (see Section 5.3):
Preconnection := NewPreconnection(LocalEndpoint?, Preconnection := NewPreconnection(LocalEndpoint?,
RemoteEndpoint?, RemoteEndpoint?,
TransportProperties, TransportProperties,
SecurityParams) SecurityParams)
The Local Endpoint MUST be specified if the Preconnection is used to The Local Endpoint MUST be specified if the Preconnection is used to
Listen() for incoming Connections, but is OPTIONAL if it is used to Listen() for incoming Connections, but is OPTIONAL if it is used to
Initiate() connections. The Remote Endpoint MUST be specified if the Initiate() connections. If no Local Endpoint is specified, the
Transport System will assign an ephemeral local port to the
Connection. The Remote Endpoint MUST be specified if the
Preconnection is used to Initiate() Connections, but is OPTIONAL if Preconnection is used to Initiate() Connections, but is OPTIONAL if
it is used to Listen() for incoming Connections. The Local Endpoint it is used to Listen() for incoming Connections. The Local Endpoint
and the Remote Endpoint MUST both be specified if a peer-to-peer and the Remote Endpoint MUST both be specified if a peer-to-peer
Rendezvous is to occur based on the Preconnection. Rendezvous is to occur based on the Preconnection.
Message Framers (see Section 9), if required, should be added to the Transport Properties MUST always be specified while security
Preconnection during pre-establishment. parameters are OPTIONAL.
If Message Framers are used (see Section 9), they MUST be added to
the Preconnection during pre-establishment.
5.1. Specifying Endpoints 5.1. Specifying Endpoints
The transport services API uses the Local Endpoint and Remote The transport services API uses the Local Endpoint and Remote
Endpoint Objects to refer to the endpoints of a transport connection. Endpoint Objects to refer to the endpoints of a transport connection.
Actions on these Objects can be used to represent various different Actions on these Objects can be used to represent various different
types of endpoint identifiers, such as IP addresses, DNS names, and types of endpoint identifiers, such as IP addresses, DNS names, and
interface names, as well as port numbers and service names. interface names, as well as port numbers and service names.
Specify a Remote Endpoint using a hostname and service name: Specify a Remote Endpoint using a hostname and service name:
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Since there could be paths over which some transport protocols are Since there could be paths over which some transport protocols are
unable to operate, or remote endpoints that support only specific unable to operate, or remote endpoints that support only specific
network addresses or transports, transport protocol selection is network addresses or transports, transport protocol selection is
necessarily tied to path selection. This may involve choosing necessarily tied to path selection. This may involve choosing
between multiple local interfaces that are connected to different between multiple local interfaces that are connected to different
access networks. access networks.
Most Selection Properties are represented as preferences, which can Most Selection Properties are represented as preferences, which can
have one of five preference levels: have one of five preference levels:
+------------+----------------------------------------+ +============+========================================+
| Preference | Effect | | Preference | Effect |
+============+========================================+ +============+========================================+
| Require | Select only protocols/paths providing | | Require | Select only protocols/paths providing |
| | the property, fail otherwise | | | the property, fail otherwise |
+------------+----------------------------------------+ +------------+----------------------------------------+
| Prefer | Prefer protocols/paths providing the | | Prefer | Prefer protocols/paths providing the |
| | property, proceed otherwise | | | property, proceed otherwise |
+------------+----------------------------------------+ +------------+----------------------------------------+
| Ignore | No preference | | Ignore | No preference |
+------------+----------------------------------------+ +------------+----------------------------------------+
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A Connection gets its Transport Properties either by being explicitly A Connection gets its Transport Properties either by being explicitly
configured via a Preconnection, by configuration after establishment, configured via a Preconnection, by configuration after establishment,
or by inheriting them from an antecedent via cloning; see Section 6.4 or by inheriting them from an antecedent via cloning; see Section 6.4
for more. for more.
Section 10.1 provides a list of Connection Properties, while Section 10.1 provides a list of Connection Properties, while
Selection Properties are listed in the subsections below. Note that Selection Properties are listed in the subsections below. Note that
many properties are only considered during establishment, and can not many properties are only considered during establishment, and can not
be changed after a Connection is established; however, they can be be changed after a Connection is established; however, they can be
queried. Querying a Selection Property after establishment yields queried. The return type of a queried Selection Property is Boolean,
the value "Require" for properties of the selected protocol and path, where "true" means that the Selection Property has been applied and
Avoid for properties avoided during selection, and Ignore for all "false" means that the Selection Property has not been applied. Note
other properties. that "true" does not mean that a request has been honored. For
example, if "Congestion control" was requested with preference level
"Prefer", but congestion control could not be supported, querying the
"congestionControl" property yields the value "false". If preference
level "Avoid" was used for "Congestion control", and, as requested,
the Connection is not congestion controlled, querying the
"congestionControl" property also yields the value "false".
An implementation of this interface must provide sensible defaults An implementation of this interface must provide sensible defaults
for Selection Properties. The defaults given for each property below for Selection Properties. The recommended default values for each
represent a configuration that can be implemented over TCP. An property below represent a configuration that can be implemented over
alternate set of default Protocol Selection Properties would TCP. If these default values are used and TCP is not supported by a
represent a configuration that can be implemented over UDP. Transport Services implementation, then an application using the
default set of Properties might not succeed in establishing a
connection. Using the same default values for independent Transport
Services implementations can be beneficical when application are
ported between different implementations, even if this default could
lead to a connection failure, as, for example, an application needs
to be explicitly designed to support a connectionless mode. In this
case the application can regonize the failure and explicitly specify
a different set of Protocol Selection Properties that result in a
usable protocol. If default values other than those recommended
below are used, it is recommended to clearly document the
differences.
5.2.1. Reliable Data Transfer (Connection) 5.2.1. Reliable Data Transfer (Connection)
Name: reliability Name: reliability
Type: Preference Type: Preference
Default: Require Default: Require
This property specifies whether the application needs to use a This property specifies whether the application needs to use a
transport protocol that ensures that all data is received on the transport protocol that ensures that all data is received on the
other side without corruption. This also entails being notified when other side without corruption. This also entails being notified when
a Connection is closed or aborted. a Connection is closed or aborted when reliable data transfer is
enabled.
5.2.2. Preservation of Message Boundaries 5.2.2. Preservation of Message Boundaries
Name: preserve-msg-boundaries Name: preserveMsgBoundaries
Type: Preference Type: Preference
Default: Prefer Default: Prefer
This property specifies whether the application needs or prefers to This property specifies whether the application needs or prefers to
use a transport protocol that preserves message boundaries. use a transport protocol that preserves message boundaries.
5.2.3. Configure Per-Message Reliability 5.2.3. Configure Per-Message Reliability
Name: per-msg-reliability Name: perMsgReliability
Type: Preference Type: Preference
Default: Ignore Default: Ignore
This property specifies whether an application considers it useful to This property specifies whether an application considers it useful to
indicate its reliability requirements on a per-Message basis. This indicate its reliability requirements on a per-Message basis. This
property applies to Connections and Connection Groups. property applies to Connections and Connection Groups.
5.2.4. Preservation of Data Ordering 5.2.4. Preservation of Data Ordering
Name: preserve-order Name: preserveOrder
Type: Preference Type: Preference
Default: Require Default: Require
This property specifies whether the application wishes to use a This property specifies whether the application wishes to use a
transport protocol that can ensure that data is received by the transport protocol that can ensure that data is received by the
application on the other end in the same order as it was sent. application on the other end in the same order as it was sent.
5.2.5. Use 0-RTT Session Establishment with an Idempotent Message 5.2.5. Use 0-RTT Session Establishment with a Safely Replayable Message
Name: zero-rtt-msg Name: zeroRttMsg
Type: Preference Type: Preference
Default: Ignore Default: Ignore
This property specifies whether an application would like to supply a This property specifies whether an application would like to supply a
Message to the transport protocol before Connection establishment, Message to the transport protocol before Connection establishment,
which will then be reliably transferred to the other side before or which will then be reliably transferred to the other side before or
during Connection establishment, potentially multiple times (i.e., during Connection establishment, potentially multiple times (i.e.,
multiple copies of the message data may be passed to the Remote multiple copies of the message data may be passed to the Remote
Endpoint). See also Section 7.5.4. Note that disabling this Endpoint). See also Section 7.5.4. Note that disabling this
property has no effect for protocols that are not connection-oriented property has no effect for protocols that are not connection-oriented
and do not protect against duplicated messages, e.g., UDP. and do not protect against duplicated messages, e.g., UDP.
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Type: Preference Type: Preference
Default: Prefer Default: Prefer
This property specifies that the application would prefer multiple This property specifies that the application would prefer multiple
Connections within a Connection Group to be provided by streams of a Connections within a Connection Group to be provided by streams of a
single underlying transport connection where possible. single underlying transport connection where possible.
5.2.7. Full Checksum Coverage on Sending 5.2.7. Full Checksum Coverage on Sending
Name: per-msg-checksum-len-send Name: perMsgChecksumLenSend
Type: Preference Type: Preference
Default: Require Default: Require
This property specifies whether the application desires protection This property specifies whether the application desires protection
against corruption for all data transmitted on this Connection. against corruption for all data transmitted on this Connection.
Disabling this property may enable to control checksum coverage later Disabling this property may enable to control checksum coverage later
(see Section 7.5.6). (see Section 7.5.6).
5.2.8. Full Checksum Coverage on Receiving 5.2.8. Full Checksum Coverage on Receiving
Name: per-msg-checksum-len-recv Name: perMsgChecksumLenRecv
Type: Preference Type: Preference
Default: Require Default: Require
This property specifies whether the application desires protection This property specifies whether the application desires protection
against corruption for all data received on this Connection. against corruption for all data received on this Connection.
5.2.9. Congestion control 5.2.9. Congestion control
Name: congestion-control Name: congestionControl
Type: Preference Type: Preference
Default: Require Default: Require
This property specifies whether the application would like the This property specifies whether the application would like the
Connection to be congestion controlled or not. Note that if a Connection to be congestion controlled or not. Note that if a
Connection is not congestion controlled, an application using such a Connection is not congestion controlled, an application using such a
Connection should itself perform congestion control in accordance Connection should itself perform congestion control in accordance
with [RFC2914]. Also note that reliability is usually combined with with [RFC2914]. Also note that reliability is usually combined with
congestion control in protocol implementations, rendering "reliable congestion control in protocol implementations, rendering "reliable
but not congestion controlled" a request that is unlikely to succeed. but not congestion controlled" a request that is unlikely to succeed.
5.2.10. Interface Instance or Type 5.2.10. Interface Instance or Type
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The set of valid interface types is implementation- and system- The set of valid interface types is implementation- and system-
specific. For example, on a mobile device, there may be "Wi-Fi" and specific. For example, on a mobile device, there may be "Wi-Fi" and
"Cellular" interface types available; whereas on a desktop computer, "Cellular" interface types available; whereas on a desktop computer,
there may be "Wi-Fi" and "Wired Ethernet" interface types available. there may be "Wi-Fi" and "Wired Ethernet" interface types available.
An implementation should provide all types that are supported on the An implementation should provide all types that are supported on the
local system to all remote systems, to allow applications to be local system to all remote systems, to allow applications to be
written generically. For example, if a single implementation is used written generically. For example, if a single implementation is used
on both mobile devices and desktop devices, it should define the on both mobile devices and desktop devices, it should define the
"Cellular" interface type for both systems, since an application may "Cellular" interface type for both systems, since an application may
want to always "Prohibit Cellular". Note that marking a specific want to always "Prohibit Cellular".
interface type as "Require" limits path selection to a small set of
interfaces, and leads to less flexible and resilient connection
establishment.
The set of interface types is expected to change over time as new The set of interface types is expected to change over time as new
access technologies become available. access technologies become available. The taxonomy of interface
types on a given Transport Services system is implementation-
specific.
Interface types should not be treated as a proxy for properties of Interface types should not be treated as a proxy for properties of
interfaces such as metered or unmetered network access. If an interfaces such as metered or unmetered network access. If an
application needs to prohibit metered interfaces, this should be application needs to prohibit metered interfaces, this should be
specified via Provisioning Domain attributes (see Section 5.2.11) or specified via Provisioning Domain attributes (see Section 5.2.11) or
another specific property. another specific property.
5.2.11. Provisioning Domain Instance or Type 5.2.11. Provisioning Domain Instance or Type
Name: pvd Name: pvd
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properties that may be more specific than network interfaces properties that may be more specific than network interfaces
[RFC7556]. [RFC7556].
As with interface instances and types, this property is a tuple of an As with interface instances and types, this property is a tuple of an
(Enumerated) PvD identifier and a preference, and can either be (Enumerated) PvD identifier and a preference, and can either be
implemented directly as such, or for making one preference available implemented directly as such, or for making one preference available
for each interface and interface type available on the system. for each interface and interface type available on the system.
The identification of a specific Provisioning Domain (PvD) is defined The identification of a specific Provisioning Domain (PvD) is defined
to be implementation- and system-specific, since there is not a to be implementation- and system-specific, since there is not a
portable standard format for a PvD identitfier. For example, this portable standard format for a PvD identifier. For example, this
identifier may be a string name or an integer. As with requiring identifier may be a string name or an integer. As with requiring
specific interfaces, requiring a specific PvD strictly limits path specific interfaces, requiring a specific PvD strictly limits path
selection. selection.
Categories or types of PvDs are also defined to be implementation- Categories or types of PvDs are also defined to be implementation-
and system-specific. These may be useful to identify a service that and system-specific. These may be useful to identify a service that
is provided by a PvD. For example, if an application wants to use a is provided by a PvD. For example, if an application wants to use a
PvD that provides a Voice-Over-IP service on a Cellular network, it PvD that provides a Voice-Over-IP service on a Cellular network, it
can use the relevant PvD type to require some PvD that provides this can use the relevant PvD type to require some PvD that provides this
service, without needing to look up a particular instance. While service, without needing to look up a particular instance. While
this does restrict path selection, it is broader than requiring this does restrict path selection, it is broader than requiring
specific PvD instances or interface instances, and should be specific PvD instances or interface instances, and should be
preferred over these options. preferred over these options.
5.2.12. Use Temporary Local Address 5.2.12. Use Temporary Local Address
Name: use-temporary-local-address Name: useTemporaryLocalAddress
Type: Preference Type: Preference
Default: Avoid for Listeners and Rendezvous Connections. Prefer for Default: Avoid for Listeners and Rendezvous Connections. Prefer for
other Connections. other Connections.
This property allows the application to express a preference for the This property allows the application to express a preference for the
use of temporary local addresses, sometimes called "privacy" use of temporary local addresses, sometimes called "privacy"
addresses [RFC4941]. Temporary addresses are generally used to addresses [RFC4941]. Temporary addresses are generally used to
prevent linking connections over time when a stable address, prevent linking connections over time when a stable address,
sometimes called "permanent" address, is not needed. Note that if an sometimes called "permanent" address, is not needed. Note that if an
application Requires the use of temporary addresses, the resulting application Requires the use of temporary addresses, the resulting
Connection cannot use IPv4, as temporary addresses do not exist in Connection cannot use IPv4, as temporary addresses do not exist in
IPv4. IPv4.
5.2.13. Parallel Use of Multiple Paths 5.2.13. Multi-Paths Transport
Name: multipath Name: multipath
Type: Enumeration Type: Enumeration
Default: Disabled Default: Disabled for connections created through initiate and
rendezvous, Passive for listeners
This property specifies whether an application wants to take This property specifies whether and how applications want to take
advantage of transferring data across multiple paths between the same advantage of transferring data across multiple paths between the same
end hosts. Using multiple paths allows connections to migrate end hosts. Using multiple paths allows connections to migrate
between interfaces as availability and performance properties change. between interfaces or aggregate bandwidth as availability and
Possible values are: performance properties change. Possible values are:
Disabled: The connection will not attempt using multiple paths once Disabled: The connection will not use multiple paths once
established established, even if the chosen transport supports using multiple
paths.
Handover: The connection should attempt to migrate between different Active: The connection will negotiate the use of multiple paths if
paths upon interface availability changes the chosen transport supports this.
Interactive: The connection should attempt to use multiple paths in Passive: The connection will support the use of multiple paths if
response to loss or delay upon individual paths the remote endpoint requests it.
Aggregate: The connection should attempt to use multiple paths in The policy for using multiple paths is specified using the separate
parallel in order to maximize bandwidth "multipath-policy" property, see Section 10.1.7 below. To enable the
peer endpoint to initiate additional paths towards a local address
other than the one initially used, it is necessary to set the
Alternative Addresses property (see Section 5.2.14 below).
Enumeration values other than "Disabled" are interpreted as Setting this property to "Active", may have privacy implications: It
preferences. enables the transport to establish connectivity using alternate paths
that may make users linkable across multiple paths, even if the
Advertisement of Alternative Addresses property (see Section 5.2.14
below) is set to false.
5.2.14. Direction of communication Enumeration values other than "Disabled" are interpreted as a
preference for choosing protocols that can make use of multiple
paths. The "Disabled" value implies a requirement not to use
multiple paths in parallel but does not prevent choosing a protocol
that is capable of using multiple paths, e.g., it does not prevent
choosing TCP, but prevents sending the "MP_CAPABLE" option in the TCP
handshake.
5.2.14. Advertisement of Alternative Addresses
Name: advertises-altaddr
Type: Boolean
Default: False
This property specifies whether alternative addresses, e.g., of other
interfaces, should be advertised to the peer endpoint by the protocol
stack. Advertising these addresses enables the peer-endpoint to
establish additional connectivity, e.g., for connection migration or
using multiple paths.
Note that this may have privacy implications because it may make
users linkable across multiple paths. Also, note that setting this
to false does not prevent the local transport system from
_establishing_ connectivity using alternate paths (see Section 5.2.13
above); it only prevents _procative advertisement_ of addresses.
5.2.15. Direction of communication
Name: direction Name: direction
Type: Enumeration Type: Enumeration
Default: Bidirectional Default: Bidirectional
This property specifies whether an application wants to use the This property specifies whether an application wants to use the
connection for sending and/or receiving data. Possible values are: connection for sending and/or receiving data. Possible values are:
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the application cannot use the connection to receive any data the application cannot use the connection to receive any data
Unidirectional receive: The connection must support receiving data, Unidirectional receive: The connection must support receiving data,
and the application cannot use the connection to send any data and the application cannot use the connection to send any data
Since unidirectional communication can be supported by transports Since unidirectional communication can be supported by transports
offering bidirectional communication, specifying unidirectional offering bidirectional communication, specifying unidirectional
communication may cause a transport stack that supports bidirectional communication may cause a transport stack that supports bidirectional
communication to be selected. communication to be selected.
5.2.15. Notification of excessive retransmissions 5.2.16. Notification of excessive retransmissions
Name: retransmit-notify Name: retransmitNotify
Type: Preference Type: Preference
Default: Ignore Default: Ignore
This property specifies whether an application considers it useful to This property specifies whether an application considers it useful to
be informed in case sent data was retransmitted more often than a be informed in case sent data was retransmitted more often than a
certain threshold (see Section 10.1.1 for configuration of this certain threshold (see Section 10.1.1 for configuration of this
threshold). threshold).
5.2.16. Notification of ICMP soft error message arrival 5.2.17. Notification of ICMP soft error message arrival
Name: soft-error-notify Name: softErrorNotify
Type: Preference Type: Preference
Default: Ignore Default: Ignore
This property specifies whether an application considers it useful to This property specifies whether an application considers it useful to
be informed when an ICMP error message arrives that does not force be informed when an ICMP error message arrives that does not force
termination of a connection. When set to true, received ICMP errors termination of a connection. When set to true, received ICMP errors
will be available as SoftErrors, see Section 10.3.1. Note that even will be available as SoftErrors, see Section 10.3.1. Note that even
if a protocol supporting this property is selected, not all ICMP if a protocol supporting this property is selected, not all ICMP
errors will necessarily be delivered, so applications cannot rely on errors will necessarily be delivered, so applications cannot rely on
receiving them. receiving them.
5.2.18. Initiating side is not the first to write
Name: activeReadBeforeSend
Type: Preference
Default: Ignore
The most common client-server communication pattern involves the
client actively opening a connection, then sending data to the
server. The server listens (passive open), reads, and then answers.
This property specifies whether an application wants to diverge from
this pattern - either by actively opening with Initiate(),
immediately followed by reading, or passively opening with Listen(),
immediately followed by writing. This property is ignored when
establishing connections using Rendezvous(). Requiring this property
limits the choice of mappings to underlying protocols, which can
reduce efficiency. For example, it prevents the transport system
from mapping Connections to SCTP streams, where the first transmitted
data takes the role of an active open signal [I-D.ietf-taps-impl].
5.3. Specifying Security Parameters and Callbacks 5.3. Specifying Security Parameters and Callbacks
Most security parameters, e.g., TLS ciphersuites, local identity and Most security parameters, e.g., TLS ciphersuites, local identity and
private key, etc., may be configured statically. Others are private key, etc., may be configured statically. Others are
dynamically configured during connection establishment. Thus, we dynamically configured during connection establishment. Thus, we
partition security parameters and callbacks based on their place in partition security parameters and callbacks based on their place in
the lifetime of connection establishment. Similar to Transport the lifetime of connection establishment. Similar to Transport
Properties, both parameters and callbacks are inherited during Properties, both parameters and callbacks are inherited during
cloning (see Section 6.4). cloning (see Section 6.4).
5.3.1. Pre-Connection Parameters 5.3.1. Pre-Connection Parameters
Common parameters such as TLS ciphersuites are known to Common parameters such as TLS ciphersuites are known to
implementations. Clients should use common safe defaults for these implementations. Clients should use common safe defaults for these
values whenever possible. However, as discussed in values whenever possible. However, as discussed in
[I-D.ietf-taps-transport-security], many transport security protocols [I-D.ietf-taps-transport-security], many transport security protocols
require specific security parameters and constraints from the client require specific security parameters and constraints from the client
at the time of configuration and actively during a handshake. These at the time of configuration and actively during a handshake. These
configuration parameters are created as follows: configuration parameters need to be specified in the pre-connection
phase and are created as follows:
SecurityParameters := NewSecurityParameters() SecurityParameters := NewSecurityParameters()
Security configuration parameters and sample usage follow: Security configuration parameters and sample usage follow:
* Local identity and private keys: Used to perform private key * Local identity and private keys: Used to perform private key
operations and prove one's identity to the Remote Endpoint. operations and prove one's identity to the Remote Endpoint.
(Note, if private keys are not available, e.g., since they are (Note, if private keys are not available, e.g., since they are
stored in hardware security modules (HSMs), handshake callbacks stored in hardware security modules (HSMs), handshake callbacks
must be used. See below for details.) must be used. See below for details.)
SecurityParameters.AddIdentity(identity) SecurityParameters.Add('identity', identity)
SecurityParameters.AddPrivateKey(privateKey, publicKey) SecurityParameters.Add('keypair', privateKey, publicKey)
* Supported algorithms: Used to restrict what parameters are used by * Supported algorithms: Used to restrict what parameters are used by
underlying transport security protocols. When not specified, underlying transport security protocols. When not specified,
these algorithms should use known and safe defaults for the these algorithms should use known and safe defaults for the
system. Parameters include: ciphersuites, supported groups, and system. Parameters include: ciphersuites, supported groups, and
signature algorithms. signature algorithms.
SecurityParameters.AddSupportedGroup(secp256k1) SecurityParameters.Add('supported-group', 'secp256k1')
SecurityParameters.AddCiphersuite(TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256) SecurityParameters.Add('ciphersuite, 'TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256')
SecurityParameters.AddSignatureAlgorithm(ed25519) SecurityParameters.Add('signature-algorithm', 'ed25519')
* Session cache management: Used to tune cache capacity, lifetime,
re-use, and eviction policies, e.g., LRU or FIFO. Constants and
policies for these interfaces are implementation-specific.
SecurityParameters.SetSessionCacheCapacity(MAX_CACHE_ELEMENTS)
SecurityParameters.SetSessionCacheLifetime(SECONDS_PER_DAY)
SecurityParameters.SetSessionCachePolicy(CachePolicyOneTimeUse)
* Pre-Shared Key import: Used to install pre-shared keying material * Pre-Shared Key import: Used to install pre-shared keying material
established out-of-band. Each pre-shared keying material is established out-of-band. Each pre-shared keying material is
associated with some identity that typically identifies its use or associated with some identity that typically identifies its use or
has some protocol-specific meaning to the Remote Endpoint. has some protocol-specific meaning to the Remote Endpoint.
SecurityParameters.AddPreSharedKey(key, identity) SecurityParameters.Add('pre-shared-key', key, identity)
* Session cache management: Used to tune cache capacity, lifetime,
re-use, and eviction policies, e.g., LRU or FIFO.may also me
changed, but are implementation-specific.
5.3.2. Connection Establishment Callbacks 5.3.2. Connection Establishment Callbacks
Security decisions, especially pertaining to trust, are not static. Security decisions, especially pertaining to trust, are not static.
Once configured, parameters may also be supplied during connection Once configured, parameters may also be supplied during connection
establishment. These are best handled as client-provided callbacks. establishment. These are best handled as client-provided callbacks.
Security handshake callbacks that may be invoked during connection Security handshake callbacks that may be invoked during connection
establishment include: establishment include:
* Trust verification callback: Invoked when a Remote Endpoint's * Trust verification callback: Invoked when a Remote Endpoint's
trust must be validated before the handshake protocol can proceed. trust must be validated before the handshake protocol can
continue.
TrustCallback := NewCallback({ TrustCallback := NewCallback({
// Handle trust, return the result // Handle trust, return the result
}) })
SecurityParameters.SetTrustVerificationCallback(trustCallback) SecurityParameters.SetTrustVerificationCallback(trustCallback)
* Identity challenge callback: Invoked when a private key operation * Identity challenge callback: Invoked when a private key operation
is required, e.g., when local authentication is requested by a is required, e.g., when local authentication is requested by a
remote. remote.
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The Initiate() Action returns a Connection object. Once Initiate() The Initiate() Action returns a Connection object. Once Initiate()
has been called, any changes to the Preconnection MUST NOT have any has been called, any changes to the Preconnection MUST NOT have any
effect on the Connection. However, the Preconnection can be reused, effect on the Connection. However, the Preconnection can be reused,
e.g., to Initiate another Connection. e.g., to Initiate another Connection.
Once Initiate is called, the candidate Protocol Stack(s) may cause Once Initiate is called, the candidate Protocol Stack(s) may cause
one or more candidate transport-layer connections to be created to one or more candidate transport-layer connections to be created to
the specified remote endpoint. The caller may immediately begin the specified remote endpoint. The caller may immediately begin
sending Messages on the Connection (see Section 7) after calling sending Messages on the Connection (see Section 7) after calling
Initate(); note that any idempotent data sent while the Connection is Initiate(); note that any data marked "Safely Replayable" that is
being established may be sent multiple times or on multiple sent while the Connection is being established may be sent multiple
candidates. times or on multiple candidates.
The following Events may be sent by the Connection after Initiate() The following Events may be sent by the Connection after Initiate()
is called: is called:
Connection -> Ready<> Connection -> Ready<>
The Ready Event occurs after Initiate has established a transport- The Ready Event occurs after Initiate has established a transport-
layer connection on at least one usable candidate Protocol Stack over layer connection on at least one usable candidate Protocol Stack over
at least one candidate Path. No Receive Events (see Section 8) will at least one candidate Path. No Receive Events (see Section 8) will
occur before the Ready Event for Connections established using occur before the Ready Event for Connections established using
Initiate. Initiate.
Connection -> InitiateError<reason?> Connection -> EstablishmentError<reason?>
An InitiateError occurs either when the set of transport properties An EstablishmentError occurs either when the set of transport
and security parameters cannot be fulfilled on a Connection for properties and security parameters cannot be fulfilled on a
initiation (e.g. the set of available Paths and/or Protocol Stacks Connection for initiation (e.g. the set of available Paths and/or
meeting the constraints is empty) or reconciled with the local and/or Protocol Stacks meeting the constraints is empty) or reconciled with
remote Endpoints; when the remote specifier cannot be resolved; or the local and/or remote Endpoints; when the remote specifier cannot
when no transport-layer connection can be established to the remote be resolved; or when no transport-layer connection can be established
Endpoint (e.g. because the remote Endpoint is not accepting to the remote Endpoint (e.g. because the remote Endpoint is not
connections, the application is prohibited from opening a Connection accepting connections, the application is prohibited from opening a
by the operating system, or the establishment attempt has timed out Connection by the operating system, or the establishment attempt has
for any other reason). timed out for any other reason).
See also Section 7.8 to combine Connection establishment and See also Section 7.8 to combine Connection establishment and
transmission of the first message in a single action. transmission of the first message in a single action.
6.2. Passive Open: Listen 6.2. Passive Open: Listen
Passive open is the Action of waiting for Connections from remote Passive open is the Action of waiting for Connections from remote
Endpoints, commonly used by servers in client-server interactions. Endpoints, commonly used by servers in client-server interactions.
Passive open is supported by this interface through the Listen Action Passive open is supported by this interface through the Listen Action
and returns a Listener object: and returns a Listener object:
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If the caller wants to rate-limit the number of inbound Connections If the caller wants to rate-limit the number of inbound Connections
that will be delivered, it can set a cap using that will be delivered, it can set a cap using
SetNewConnectionLimit(). This mechanism allows a server to protect SetNewConnectionLimit(). This mechanism allows a server to protect
itself from being drained of resources. Each time a new Connection itself from being drained of resources. Each time a new Connection
is delivered by the ConnectionReceived Event, the value is is delivered by the ConnectionReceived Event, the value is
automatically decremented. Once the value reaches zero, no further automatically decremented. Once the value reaches zero, no further
Connections will be delivered until the caller sets the limit to a Connections will be delivered until the caller sets the limit to a
higher value. By default, this value is Infinite. The caller is higher value. By default, this value is Infinite. The caller is
also able to reset the value to Infinite at any point. also able to reset the value to Infinite at any point.
Listener -> ListenError<reason?> Listener -> EstablishmentError<reason?>
A ListenError occurs either when the Properties and Security A EstablishmentError occurs either when the Properties and Security
Parameters of the Preconnection cannot be fulfilled for listening or Parameters of the Preconnection cannot be fulfilled for listening or
cannot be reconciled with the Local Endpoint (and/or Remote Endpoint, cannot be reconciled with the Local Endpoint (and/or Remote Endpoint,
if specified), when the Local Endpoint (or Remote Endpoint, if if specified), when the Local Endpoint (or Remote Endpoint, if
specified) cannot be resolved, or when the application is prohibited specified) cannot be resolved, or when the application is prohibited
from listening by policy. from listening by policy.
Listener -> Stopped<> Listener -> Stopped<>
A Stopped Event occurs after the Listener has stopped listening. A Stopped Event occurs after the Listener has stopped listening.
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Preconnection -> RendezvousDone<Connection> Preconnection -> RendezvousDone<Connection>
The RendezvousDone<> Event occurs when a Connection is established The RendezvousDone<> Event occurs when a Connection is established
with the Remote Endpoint. For Connection-oriented transports, this with the Remote Endpoint. For Connection-oriented transports, this
occurs when the transport-layer connection is established; for occurs when the transport-layer connection is established; for
Connectionless transports, it occurs when the first Message is Connectionless transports, it occurs when the first Message is
received from the Remote Endpoint. The resulting Connection is received from the Remote Endpoint. The resulting Connection is
contained within the RendezvousDone<> Event, and is ready to use as contained within the RendezvousDone<> Event, and is ready to use as
soon as it is passed to the application via the Event. soon as it is passed to the application via the Event.
Preconnection -> RendezvousError<reason?> Preconnection -> EstablishmentError<reason?>
An RendezvousError occurs either when the Properties and Security An EstablishmentError occurs either when the Properties and Security
Parameters of the Preconnection cannot be fulfilled for rendezvous or Parameters of the Preconnection cannot be fulfilled for rendezvous or
cannot be reconciled with the Local and/or Remote Endpoints, when the cannot be reconciled with the Local and/or Remote Endpoints, when the
Local Endpoint or Remote Endpoint cannot be resolved, when no Local Endpoint or Remote Endpoint cannot be resolved, when no
transport-layer connection can be established to the Remote Endpoint, transport-layer connection can be established to the Remote Endpoint,
or when the application is prohibited from rendezvous by policy. or when the application is prohibited from rendezvous by policy.
When using some NAT traversal protocols, e.g., Interactive When using some NAT traversal protocols, e.g., Interactive
Connectivity Establishment (ICE) [RFC5245], it is expected that the Connectivity Establishment (ICE) [RFC5245], it is expected that the
Local Endpoint will be configured with some method of discovering NAT Local Endpoint will be configured with some method of discovering NAT
bindings, e.g., a Session Traversal Utilities for NAT (STUN) server. bindings, e.g., a Session Traversal Utilities for NAT (STUN) server.
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described in Section 7.6. described in Section 7.6.
Framers can be used to extend or modify the message data with Framers can be used to extend or modify the message data with
additional information that can be processed at the receiver to additional information that can be processed at the receiver to
detect message boundaries. This is further decribed in Section 9. detect message boundaries. This is further decribed in Section 9.
7.1. Basic Sending 7.1. Basic Sending
The most basic form of sending on a connection involves enqueuing a The most basic form of sending on a connection involves enqueuing a
single Data block as a complete Message, with default Message single Data block as a complete Message, with default Message
Properties. Message data is transferred as an array of bytes, and Properties.
the resulting object contains both the byte array and the length of
the array.
messageData := "hello".bytes() messageData := "hello"
Connection.Send(messageData) Connection.Send(messageData)
The interpretation of a Message to be sent is dependent on the The interpretation of a Message to be sent is dependent on the
implementation, and on the constraints on the Protocol Stacks implied implementation, and on the constraints on the Protocol Stacks implied
by the Connection's transport properties. For example, a Message may by the Connection's transport properties. For example, a Message may
be a single datagram for UDP Connections; or an HTTP Request for HTTP be a single datagram for UDP Connections; or an HTTP Request for HTTP
Connections. Connections.
Some transport protocols can deliver arbitrarily sized Messages, but Some transport protocols can deliver arbitrarily sized Messages, but
other protocols constrain the maximum Message size. Applications can other protocols constrain the maximum Message size. Applications can
query the Connection Property "Maximum Message size on send" query the Connection Property "Maximum Message size on send"
(Section 10.1.8.3) to determine the maximum size allowed for a single (Section 10.1.9.3) to determine the maximum size allowed for a single
Message. If a Message is too large to fit in the Maximum Message Message. If a Message is too large to fit in the Maximum Message
Size for the Connection, the Send will fail with a SendError event Size for the Connection, the Send will fail with a SendError event
(Section 7.3.3). For example, it is invalid to send a Message over a (Section 7.3.3). For example, it is invalid to send a Message over a
UDP connection that is larger than the available datagram sending UDP connection that is larger than the available datagram sending
size. size.
7.2. Sending Replies 7.2. Sending Replies
When a message is sent in response to a message received, the When a message is sent in response to a message received, the
application may use the Message Context of the received Message to application may use the Message Context of the received Message to
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that the message to be sent is a response and can map the response to that the message to be sent is a response and can map the response to
the same underlying transport connection or stream the request was the same underlying transport connection or stream the request was
received from. The concept of Message Contexts is described in received from. The concept of Message Contexts is described in
Section 7.4. Section 7.4.
7.3. Send Events 7.3. Send Events
Like all Actions in this interface, the Send Action is asynchronous. Like all Actions in this interface, the Send Action is asynchronous.
There are several Events that can be delivered in response to Sending There are several Events that can be delivered in response to Sending
a Message. Exactly one Event (Sent, Expired, or SendError) will be a Message. Exactly one Event (Sent, Expired, or SendError) will be
delivered in reponse to each call to Send. delivered in response to each call to Send.
Note that if partial Sends are used (Section 7.6), there will still Note that if partial Sends are used (Section 7.6), there will still
be exactly one Send Event delivered for each call to Send. For be exactly one Send Event delivered for each call to Send. For
example, if a Message expired while two requests to Send data for example, if a Message expired while two requests to Send data for
that Message are outstanding, there will be two Expired events that Message are outstanding, there will be two Expired events
delivered. delivered.
The interface should allow the application to correlate which Send
Action resulted in a particular Send Event. The manner in which this
correlation is indicated is implementation-specific.
7.3.1. Sent 7.3.1. Sent
Connection -> Sent<messageContext> Connection -> Sent<messageContext>
The Sent Event occurs when a previous Send Action has completed, The Sent Event occurs when a previous Send Action has completed,
i.e., when the data derived from the Message has been passed down or i.e., when the data derived from the Message has been passed down or
through the underlying Protocol Stack and is no longer the through the underlying Protocol Stack and is no longer the
responsibility of this interface. The exact disposition of the responsibility of this interface. The exact disposition of the
Message (i.e., whether it has actually been transmitted, moved into a Message (i.e., whether it has actually been transmitted, moved into a
buffer on the network interface, moved into a kernel buffer, and so buffer on the network interface, moved into a kernel buffer, and so
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left empty. To get or set meta-data for a Framer, the application left empty. To get or set meta-data for a Framer, the application
has to pass a reference to this Framer as the scope parameter. has to pass a reference to this Framer as the scope parameter.
For MessageContexts returned by send events (see Section 7.3) and For MessageContexts returned by send events (see Section 7.3) and
receive events (see Section 8.2), the application can query receive events (see Section 8.2), the application can query
information about the local and remote endpoint: information about the local and remote endpoint:
RemoteEndpoint := MessageContext.GetRemoteEndpoint() RemoteEndpoint := MessageContext.GetRemoteEndpoint()
LocalEndpoint := MessageContext.GetLocalEndpoint() LocalEndpoint := MessageContext.GetLocalEndpoint()
Message Contexts can also be used to send messages that are flagged Message Contexts can also be used to send messages in reply to other
as a reply to other messages, see Section 7.2 for details. If the messages, see Section 7.2 for details.
message received was sent by the remote endpoint as a reply to an
earlier message and the Protocol Stack provides this information, the
MessageContext of the original request can be accessed using the
Message Context of the reply:
RequestMessageContext := MessageContext.GetOriginalRequest()
7.5. Message Properties 7.5. Message Properties
Applications may need to annotate the Messages they send with extra Applications may need to annotate the Messages they send with extra
information to control how data is scheduled and processed by the information to control how data is scheduled and processed by the
transport protocols in the Connection. Therefore a message context transport protocols in the Connection. Therefore a message context
containing these properties can be passed to the Send Action. For containing these properties can be passed to the Send Action. For
other uses of the message context, see Section 7.4. other uses of the message context, see Section 7.4.
Note that Message Properties are per-Message, not per-Send if partial Note that Message Properties are per-Message, not per-Send if partial
Messages are sent (Section 7.6). All data blocks associated with a Messages are sent (Section 7.6). All data blocks associated with a
single Message share properties specified in the Message Contexts. single Message share properties specified in the Message Contexts.
For example, it would not make sense to have the beginning of a For example, it would not make sense to have the beginning of a
Message expire, but allow the end of a Message to still be sent. Message expire, but allow the end of a Message to still be sent.
A MessageContext object contains metadata for Messages to be sent or A MessageContext object contains metadata for Messages to be sent or
received. received.
messageData := "hello".bytes() messageData := "hello"
messageContext := NewMessageContext() messageContext := NewMessageContext()
messageContext.add(parameter, value) messageContext.add(parameter, value)
Connection.Send(messageData, messageContext) Connection.Send(messageData, messageContext)
The simpler form of Send, which does not take any messageContext, is The simpler form of Send, which does not take any messageContext, is
equivalent to passing a default MessageContext without adding any equivalent to passing a default MessageContext without adding any
Message Properties to it. Message Properties to it.
If an application wants to override Message Properties for a specific If an application wants to override Message Properties for a specific
message, it can acquire an empty MessageContext Object and add all message, it can acquire an empty MessageContext Object and add all
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context is used for sending. Once a messageContext has been used context is used for sending. Once a messageContext has been used
with a Send call, modifying any of its properties is invalid. with a Send call, modifying any of its properties is invalid.
Message Properties may be inconsistent with the properties of the Message Properties may be inconsistent with the properties of the
Protocol Stacks underlying the Connection on which a given Message is Protocol Stacks underlying the Connection on which a given Message is
sent. For example, a Connection must provide reliability to allow sent. For example, a Connection must provide reliability to allow
setting an infinite value for the lifetime property of a Message. setting an infinite value for the lifetime property of a Message.
Sending a Message with Message Properties inconsistent with the Sending a Message with Message Properties inconsistent with the
Selection Properties of the Connection yields an error. Selection Properties of the Connection yields an error.
Connection Properties describe the default behavior for all Messages
on a Connection. If a Message Property contradicts a Connection
Property, and if this per-Message behavior can be supported, it
overrides the Connection Property for the specific Message. For
example, if "Reliable Data Transfer (Connection)" is set to "Require"
and a protocol with configurable per-Message reliability is used,
setting "Reliable Data Transfer (Message)" to "false" for a
particular Message will allow this Message to be unreliably
delivered. Note that changing the Reliable Data Transfer property on
Messages is only possible for Connections that were established with
the Selection Property "Configure Per-Message Reliability" enabled.
The following Message Properties are supported: The following Message Properties are supported:
7.5.1. Lifetime 7.5.1. Lifetime
Name: msg-lifetime Name: msgLifetime
Type: Numeric Type: Numeric
Default: infinite Default: infinite
Lifetime specifies how long a particular Message can wait to be sent Lifetime specifies how long a particular Message can wait to be sent
to the remote endpoint before it is irrelevant and no longer needs to to the remote endpoint before it is irrelevant and no longer needs to
be (re-)transmitted. This is a hint to the transport system - it is be (re-)transmitted. This is a hint to the transport system - it is
not guaranteed that a Message will not be sent when its Lifetime has not guaranteed that a Message will not be sent when its Lifetime has
expired. expired.
Setting a Message's Lifetime to infinite indicates that the Setting a Message's Lifetime to infinite indicates that the
application does not wish to apply a time constraint on the application does not wish to apply a time constraint on the
transmission of the Message, but it does not express a need for transmission of the Message, but it does not express a need for
reliable delivery; reliability is adjustable per Message via the reliable delivery; reliability is adjustable per Message via the
"Reliable Data Transfer (Message)" property (see Section 7.5.7). The "Reliable Data Transfer (Message)" property (see Section 7.5.7). The
type and units of Lifetime are implementation-specific. type and units of Lifetime are implementation-specific.
7.5.2. Priority 7.5.2. Priority
Name: msg-prio Name: msgPrio
Type: Integer (non-negative) Type: Integer (non-negative)
Default: 100 Default: 100
This property represents a hierarchy of priorities. It can specify This property represents a hierarchy of priorities. It can specify
the priority of a Message, relative to other Messages sent over the the priority of a Message, relative to other Messages sent over the
same Connection. same Connection.
A Message with Priority 0 will yield to a Message with Priority 1, A Message with Priority 0 will yield to a Message with Priority 1,
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specify priorities on the wire for Protocol Stacks supporting specify priorities on the wire for Protocol Stacks supporting
prioritization. prioritization.
Note that this property is not a per-message override of the Note that this property is not a per-message override of the
connection Priority - see Section 10.1.3. Both Priority properties connection Priority - see Section 10.1.3. Both Priority properties
may interact, but can be used independently and be realized by may interact, but can be used independently and be realized by
different mechanisms. different mechanisms.
7.5.3. Ordered 7.5.3. Ordered
Name: msg-ordered Name: msgOrdered
Type: Boolean Type: Boolean
Default: true Default: true
If true, it specifies that the receiver-side transport protocol stack If true, it specifies that the receiver-side transport protocol stack
may only deliver the Message to the receiving application after the may only deliver the Message to the receiving application after the
previous ordered Message which was passed to the same Connection via previous ordered Message which was passed to the same Connection via
the Send Action, when such a Message exists. If false, the Message the Send Action, when such a Message exists. If false, the Message
may be delivered to the receiving application out of order. This may be delivered to the receiving application out of order. This
property is used for protocols that support preservation of data property is used for protocols that support preservation of data
ordering, see Section 5.2.4, but allow out-of-order delivery for ordering, see Section 5.2.4, but allow out-of-order delivery for
certain messages, e.g., by multiplexing independent messages onto certain messages, e.g., by multiplexing independent messages onto
different streams. different streams.
7.5.4. Idempotent 7.5.4. Safely Replayable
Name: idempotent Name: safelyReplayable
Type: Boolean Type: Boolean
Default: false Default: false
If true, it specifies that a Message is safe to send to the remote If true, it specifies that a Message is safe to send to the remote
endpoint more than once for a single Send Action. It is used to mark endpoint more than once for a single Send Action. It is used to mark
data safe for certain 0-RTT establishment techniques, where data safe for certain 0-RTT establishment techniques, where
retransmission of the 0-RTT data may cause the remote application to retransmission of the 0-RTT data may cause the remote application to
receive the Message multiple times. receive the Message multiple times.
Note that for protocols that do not protect against duplicated Note that for protocols that do not protect against duplicated
messages, e.g., UDP, all messages MUST be marked as Idempotent. In messages, e.g., UDP, all messages MUST be marked as "Safely
order to enable protocol selection to choose such a protocol, Replayable". In order to enable protocol selection to choose such a
Idempotent MUST be added to the TransportProperties passed to the protocol, "Safely Replayable" MUST be added to the
Preconnection. If such a protocol was chosen, disabling Idempotent TransportProperties passed to the Preconnection. If such a protocol
on individual messages MUST result in a SendError. was chosen, disabling "Safely Replayable" on individual messages MUST
result in a SendError.
7.5.5. Final 7.5.5. Final
Type: Boolean
Name: final Name: final
Type: Boolean
Default: false Default: false
If true, this Message is the last one that the application will send If true, this Message is the last one that the application will send
on a Connection. This allows underlying protocols to indicate to the on a Connection. This allows underlying protocols to indicate to the
Remote Endpoint that the Connection has been effectively closed in Remote Endpoint that the Connection has been effectively closed in
the sending direction. For example, TCP-based Connections can send a the sending direction. For example, TCP-based Connections can send a
FIN once a Message marked as Final has been completely sent, FIN once a Message marked as Final has been completely sent,
indicated by marking endOfMessage. Protocols that do not support indicated by marking endOfMessage. Protocols that do not support
signalling the end of a Connection in a given direction will ignore signalling the end of a Connection in a given direction will ignore
this property. this property.
Note that a Final Message must always be sorted to the end of a list Note that a Final Message must always be sorted to the end of a list
of Messages. The Final property overrides Priority and any other of Messages. The Final property overrides Priority and any other
property that would re-order Messages. If another Message is sent property that would re-order Messages. If another Message is sent
after a Message marked as Final has already been sent on a after a Message marked as Final has already been sent on a
Connection, the Send Action for the new Message will cause a Connection, the Send Action for the new Message will cause a
SendError Event. SendError Event.
7.5.6. Corruption Protection Length 7.5.6. Corruption Protection Length
Name: msg-checksum-len Name: msgChecksumLen
Type: Integer (non-negative with -1 as special value) Type: Integer (non-negative with special value "Full Coverage")
Default: -1 (full coverage) Default: Full Coverage
This property specifies the minimum length of the section of the This property specifies the minimum length of the section of the
Message, starting from byte 0, that the application requires to be Message, starting from byte 0, that the application requires to be
delivered without corruption due to lower layer errors. It is used delivered without corruption due to lower layer errors. It is used
to specify options for simple integrity protection via checksums. A to specify options for simple integrity protection via checksums. A
value of 0 means that no checksum is required, and -1 means that the value of 0 means that no checksum is required, and "Full Coverage"
entire Message is protected by a checksum. Only full coverage is means that the entire Message is protected by a checksum. Only "Full
guaranteed, any other requests are advisory, meaning that full Coverage" is guaranteed, any other requests are advisory, meaning
coverage is applied anyway. that "Full Coverage" is applied anyway.
7.5.7. Reliable Data Transfer (Message) 7.5.7. Reliable Data Transfer (Message)
Name: msg-reliable Name: msgReliable
Type: Boolean Type: Boolean
Default: true Default: true
When true, this property specifies that a message should be sent in When true, this property specifies that a message should be sent in
such a way that the transport protocol ensures all data is received such a way that the transport protocol ensures all data is received
on the other side without corruption. Changing the 'Reliable Data on the other side without corruption. Changing the "Reliable Data
Transfer' property on Messages is only possible for Connections that Transfer" property on Messages is only possible for Connections that
were established with the Selection Property 'Configure Per-Message were established with the Selection Property "Configure Per-Message
Reliability' enabled. When this is not the case, changing it will Reliability" enabled. When this is not the case, changing it will
generate an error. Disabling this property indicates that the generate an error. Disabling this property indicates that the
transport system may disable retransmissions or other reliability transport system may disable retransmissions or other reliability
mechanisms for this particular Message, but such disabling is not mechanisms for this particular Message, but such disabling is not
guaranteed. guaranteed.
7.5.8. Message Capacity Profile Override 7.5.8. Message Capacity Profile Override
Name: msg-capacity-profile Name: msgCapacityProfile
Type: Enumeration Type: Enumeration
This enumerated property specifies the application's preferred This enumerated property specifies the application's preferred
tradeoffs for sending this Message; it is a per-Message override of tradeoffs for sending this Message; it is a per-Message override of
the Capacity Profile connection property (see Section 10.1.6). the Capacity Profile connection property (see Section 10.1.6).
7.5.9. Singular Transmission 7.5.9. No Fragmentation
Name: singular-transmission
Name: noFragmentation
Type: Boolean Type: Boolean
Default: false Default: false
This property specifies that a message should be sent and received as This property specifies that a message should be sent and received as
a single packet without transport-layer segmentation or network-layer a single packet without network-layer fragmentation, if possible.
fragmentation, if possible. Attempts to send a message with this Attempts to send a message with this property set with a size greater
property set with a size greater to the transport's current estimate to the transport's current estimate of its maximum transmission
of its maximum transmission segment size will result in a segment size will result in a "SendError". When used with transports
"SendError". When used with transports supporting this functionality supporting this functionality and running over IP version 4, the
and running over IP version 4, the Don't Fragment bit will be set. Don't Fragment bit will be set.
7.6. Partial Sends 7.6. Partial Sends
It is not always possible for an application to send all data It is not always possible for an application to send all data
associated with a Message in a single Send Action. The Message data associated with a Message in a single Send Action. The Message data
may be too large for the application to hold in memory at one time, may be too large for the application to hold in memory at one time,
or the length of the Message may be unknown or unbounded. or the length of the Message may be unknown or unbounded.
Partial Message sending is supported by passing an endOfMessage Partial Message sending is supported by passing an endOfMessage
boolean parameter to the Send Action. This value is always true by boolean parameter to the Send Action. This value is always true by
default, and the simpler forms of Send are equivalent to passing true default, and the simpler forms of Send are equivalent to passing true
for endOfMessage. for endOfMessage.
The following example sends a Message in two separate calls to Send. The following example sends a Message in two separate calls to Send.
messageContext := NewMessageContext() messageContext := NewMessageContext()
messageContext.add(parameter, value) messageContext.add(parameter, value)
messageData := "hel".bytes() messageData := "hel"
endOfMessage := false endOfMessage := false
Connection.Send(messageData, messageContext, endOfMessage) Connection.Send(messageData, messageContext, endOfMessage)
messageData := "lo".bytes() messageData := "lo"
endOfMessage := true endOfMessage := true
Connection.Send(messageData, messageContext, endOfMessage) Connection.Send(messageData, messageContext, endOfMessage)
All data sent with the same MessageContext object will be treated as All data sent with the same MessageContext object will be treated as
belonging to the same Message, and will constitute an in-order series belonging to the same Message, and will constitute an in-order series
until the endOfMessage is marked. Once the end of the Message is until the endOfMessage is marked.
marked, the MessageContext object may be re-used as a new Message
with identical parameters.
7.7. Batching Sends 7.7. Batching Sends
To reduce the overhead of sending multiple small Messages on a To reduce the overhead of sending multiple small Messages on a
Connection, the application may want to batch several Send actions Connection, the application may want to batch several Send Actions
together. This provides a hint to the system that the sending of together. This provides a hint to the system that the sending of
these Messages should be coalesced when possible, and that sending these Messages should be coalesced when possible, and that sending
any of the batched Messages may be delayed until the last Message in any of the batched Messages may be delayed until the last Message in
the batch is enqueued. the batch is enqueued.
Connection.Batch( The semantics for starting and ending a batch can be implementation-
Connection.Send(messageData) specific, but need to allow multiple Send Actions to be enqueued.
Connection.Send(messageData)
) Connection.StartBatch()
Connection.Send(messageData)
Connection.Send(messageData)
Connection.EndBatch()
7.8. Send on Active Open: InitiateWithSend 7.8. Send on Active Open: InitiateWithSend
For application-layer protocols where the Connection initiator also For application-layer protocols where the Connection initiator also
sends the first message, the InitiateWithSend() action combines sends the first message, the InitiateWithSend() action combines
Connection initiation with a first Message sent: Connection initiation with a first Message sent:
Connection := Preconnection.InitiateWithSend(messageData, messageContext?, timeout?) Connection := Preconnection.InitiateWithSend(messageData, messageContext?, timeout?)
Whenever possible, a messageContext should be provided to declare the Whenever possible, a messageContext should be provided to declare the
message passed to InitiateWithSend as idempotent. This allows the Message passed to InitiateWithSend as "Safely Replayable". This
transport system to make use of 0-RTT establishment in case this is allows the transport system to make use of 0-RTT establishment in
supported by the available protocol stacks. When the selected case this is supported by the available protocol stacks. When the
stack(s) do not support transmitting data upon connection selected stack(s) do not support transmitting data upon connection
establishment, InitiateWithSend is identical to Initiate() followed establishment, InitiateWithSend is identical to Initiate() followed
by Send(). by Send().
Neither partial sends nor send batching are supported by Neither partial sends nor send batching are supported by
InitiateWithSend(). InitiateWithSend().
The Events that may be sent after InitiateWithSend() are equivalent The Events that may be sent after InitiateWithSend() are equivalent
to those that would be sent by an invocation of Initate() followed to those that would be sent by an invocation of Initiate() followed
immediately by an invocation of Send(), with the caveat that a send immediately by an invocation of Send(), with the caveat that a send
failure that occurs because the Connection could not be established failure that occurs because the Connection could not be established
will not result in a SendError separate from the InitiateError will not result in a SendError separate from the InitiateError
signaling the failure of Connection establishment. signaling the failure of Connection establishment.
8. Receiving Data 8. Receiving Data
Once a Connection is established, it can be used for receiving data. Once a Connection is established, it can be used for receiving data
As with sending, data is received in terms of Messages. Receiving is (unless the "Direction of Communication" property is set to
an asynchronous operation, in which each call to Receive enqueues a "unidirectional send"). As with sending, data is received in terms
request to receive new data from the connection. Once data has been of Messages. Receiving is an asynchronous operation, in which each
received, or an error is encountered, an event will be delivered to call to Receive enqueues a request to receive new data from the
complete any pending Receive requests (see Section 8.2). If Messages connection. Once data has been received, or an error is encountered,
arrive at the transport system before Receive requests are issued, an event will be delivered to complete any pending Receive requests
ensuing Receive requests will first operate on these Messages before (see Section 8.2). If Messages arrive at the transport system before
awaiting any further Messages. Receive requests are issued, ensuing Receive requests will first
operate on these Messages before awaiting any further Messages.
8.1. Enqueuing Receives 8.1. Enqueuing Receives
Receive takes two parameters to specify the length of data that an Receive takes two parameters to specify the length of data that an
application is willing to receive, both of which are optional and application is willing to receive, both of which are optional and
have default values if not specified. have default values if not specified.
Connection.Receive(minIncompleteLength?, maxLength?) Connection.Receive(minIncompleteLength?, maxLength?)
By default, Receive will try to deliver complete Messages in a single By default, Receive will try to deliver complete Messages in a single
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minIncompleteLength are intended only to manage buffering, and are minIncompleteLength are intended only to manage buffering, and are
not interpreted as a receiver preference for message reordering. not interpreted as a receiver preference for message reordering.
8.2. Receive Events 8.2. Receive Events
Each call to Receive will be paired with a single Receive Event, Each call to Receive will be paired with a single Receive Event,
which can be a success or an error. This allows an application to which can be a success or an error. This allows an application to
provide backpressure to the transport stack when it is temporarily provide backpressure to the transport stack when it is temporarily
not ready to receive messages. not ready to receive messages.
The interface should allow the application to correlate which call to
Receive resulted in a particular Receive Event. The manner in which
this correlation is indicated is implementation-specific.
8.2.1. Received 8.2.1. Received
Connection -> Received<messageData, messageContext> Connection -> Received<messageData, messageContext>
A Received event indicates the delivery of a complete Message. It A Received event indicates the delivery of a complete Message. It
contains two objects, the received bytes as messageData, and the contains two objects, the received bytes as messageData, and the
metadata and properties of the received Message as messageContext. metadata and properties of the received Message as messageContext.
The messageData object provides access to the bytes that were The messageData object provides access to the bytes that were
received for this Message, along with the length of the byte array. received for this Message, along with the length of the byte array.
The messageContext is provided to enable retrieving metadata about The messageContext is provided to enable retrieving metadata about
the message and referring to the message, e.g., to send replies and the message and referring to the message, e.g., to send replies and
map responses to their requests. See Section 7.4 for details. map responses to their requests. See Section 7.4 for details.
See Section 9 for handling Message framing in situations where the See Section 9 for handling Message framing in situations where the
Protocol Stack only provides a byte-stream transport. Protocol Stack only provides a byte-stream transport.
8.2.2. ReceivedPartial 8.2.2. ReceivedPartial
Connection -> ReceivedPartial<messageData, messageContext, endOfMessage> Connection -> ReceivedPartial<messageData, messageContext, endOfMessage>
If a complete Message cannot be delivered in one event, one part of If a complete Message cannot be delivered in one event, one part of
the Message may be delivered with a ReceivedPartial event. In order the Message may be delivered with a ReceivedPartial event. In order
to continue to receive more of the same Message, the application must to continue to receive more of the same Message, the application must
invoke Receive again. invoke Receive again.
Multiple invocations of ReceivedPartial deliver data for the same Multiple invocations of ReceivedPartial deliver data for the same
Message by passing the same MessageContext, until the endOfMessage Message by passing the same MessageContext, until the endOfMessage
flag is delivered or a ReceiveError occurs. All partial blocks of a flag is delivered or a ReceiveError occurs. All partial blocks of a
single Message are delivered in order without gaps. This event does single Message are delivered in order without gaps. This event does
not support delivering discontiguous partial Messages. not support delivering discontiguous partial Messages.
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8.3.2. Early Data 8.3.2. Early Data
In some cases it may be valuable to know whether data was read as In some cases it may be valuable to know whether data was read as
part of early data transfer (before connection establishment has part of early data transfer (before connection establishment has
finished). This is useful if applications need to treat early data finished). This is useful if applications need to treat early data
separately, e.g., if early data has different security properties separately, e.g., if early data has different security properties
than data sent after connection establishment. In the case of TLS than data sent after connection establishment. In the case of TLS
1.3, client early data can be replayed maliciously (see [RFC8446]). 1.3, client early data can be replayed maliciously (see [RFC8446]).
Thus, receivers may wish to perform additional checks for early data Thus, receivers may wish to perform additional checks for early data
to ensure it is idempotent or not replayed. If TLS 1.3 is available to ensure it is safely replayable. If TLS 1.3 is available and the
and the recipient Message was sent as part of early data, the recipient Message was sent as part of early data, the corresponding
corresponding metadata carries a flag indicating as such. If early metadata carries a flag indicating as such. If early data is
data is enabled, applications should check this metadata field for enabled, applications should check this metadata field for Messages
Messages received during connection establishment and respond received during connection establishment and respond accordingly.
accordingly.
8.3.3. Receiving Final Messages 8.3.3. Receiving Final Messages
The Message Context can indicate whether or not this Message is the The Message Context can indicate whether or not this Message is the
Final Message on a Connection. For any Message that is marked as Final Message on a Connection. For any Message that is marked as
Final, the application can assume that there will be no more Messages Final, the application can assume that there will be no more Messages
received on the Connection once the Message has been completely received on the Connection once the Message has been completely
delivered. This corresponds to the Final property that may be marked delivered. This corresponds to the Final property that may be marked
on a sent Message, see Section 7.5.5. on a sent Message, see Section 7.5.5.
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Generic Connection Properties are defined independent of the chosen Generic Connection Properties are defined independent of the chosen
protocol stack and therefore available on all Connections. protocol stack and therefore available on all Connections.
Note that many Connection Properties have a corresponding Selection Note that many Connection Properties have a corresponding Selection
Property which enables applications to express their preference for Property which enables applications to express their preference for
protocols providing a supporting transport feature. protocols providing a supporting transport feature.
10.1.1. Retransmission Threshold Before Excessive Retransmission 10.1.1. Retransmission Threshold Before Excessive Retransmission
Notification Notification
Name: retransmit-notify-threshold Name: retransmitNotifyThreshold
Type: Integer Type: Integer, with special value "Disabled"
Default: -1 Default: Disabled
This property specifies after how many retransmissions to inform the This property specifies after how many retransmissions to inform the
application about "Excessive Retransmissions". The special value -1 application about "Excessive Retransmissions".
means that this notification is disabled.
10.1.2. Required Minimum Corruption Protection Coverage for Receiving 10.1.2. Required Minimum Corruption Protection Coverage for Receiving
Name: recv-checksum-len Name: recvChecksumLen
Type: Integer
Default: -1 Type: Integer, with special value "Full Coverage"
Default: Full Coverage
This property specifies the part of the received data that needs to This property specifies the part of the received data that needs to
be covered by a checksum. It is given in Bytes. A value of 0 means be covered by a checksum. It is given in Bytes. A value of 0 means
that no checksum is required, and the special value -1 indicates full that no checksum is required.
checksum coverage.
10.1.3. Priority (Connection) 10.1.3. Priority (Connection)
Name: conn-prio Name: connPrio
Type: Integer Type: Integer
Default: 100 Default: 100
This Property is a non-negative integer representing the relative This Property is a non-negative integer representing the relative
inverse priority (i.e., a lower value reflects a higher priority) of inverse priority (i.e., a lower value reflects a higher priority) of
this Connection relative to other Connections in the same Connection this Connection relative to other Connections in the same Connection
Group. It has no effect on Connections not part of a Connection Group. It has no effect on Connections not part of a Connection
Group. As noted in Section 6.4, this property is not entangled when Group. As noted in Section 6.4, this property is not entangled when
Connections are cloned, i.e., changing the Priority on one Connection Connections are cloned, i.e., changing the Priority on one Connection
in a Connection Group does not change it on the other Connections in in a Connection Group does not change it on the other Connections in
the same Connection Group. the same Connection Group.
10.1.4. Timeout for Aborting Connection 10.1.4. Timeout for Aborting Connection
Name: conn-timeout Name: connTimeout
Type: Numeric Type: Numeric, with special value "Disabled"
Default: -1 Default: Disabled
This property specifies how long to wait before deciding that a This property specifies how long to wait before deciding that a
Connection has failed when trying to reliably deliver data to the Connection has failed when trying to reliably deliver data to the
destination. Adjusting this Property will only take effect when the destination. Adjusting this Property will only take effect when the
underlying stack supports reliability. The special value -1 means underlying stack supports reliability. The special value "Disabled"
that this timeout is not scheduled to happen. This can be a valid means that this timeout is not scheduled to happen. This can be a
choice with unreliable data transfer (e.g., when UDP is the valid choice with unreliable data transfer (e.g., when UDP is the
underlying transport protocol). underlying transport protocol).
10.1.5. Connection Group Transmission Scheduler 10.1.5. Connection Group Transmission Scheduler
Name: conn-scheduler Name: connScheduler
Type: Enumeration Type: Enumeration
Default: Weighted Fair Queueing (see Section 3.6 in [RFC8260]) Default: Weighted Fair Queueing (see Section 3.6 in [RFC8260])
This property specifies which scheduler should be used among This property specifies which scheduler should be used among
Connections within a Connection Group, see Section 6.4. The set of Connections within a Connection Group, see Section 6.4. The set of
schedulers can be taken from [RFC8260]. schedulers can be taken from [RFC8260].
10.1.6. Capacity Profile 10.1.6. Capacity Profile
Name: conn-capacity-profile Name: connCapacityProfile
This property specifies the desired network treatment for traffic This property specifies the desired network treatment for traffic
sent by the application and the tradeoffs the application is prepared sent by the application and the tradeoffs the application is prepared
to make in path and protocol selection to receive that desired to make in path and protocol selection to receive that desired
treatment. When the capacity profile is set to a value other than treatment. When the capacity profile is set to a value other than
Default, the transport system SHOULD select paths and configure Default, the transport system SHOULD select paths and configure
protocols to optimize the tradeoff between delay, delay variation, protocols to optimize the tradeoff between delay, delay variation,
and bandwidth efficiency based on the capacity profile specified. and efficient use of the available capacity based on the capacity
How this is realized is implementation-specific. The Capacity profile specified. How this is realized is implementation-specific.
Profile MAY also be used to set priorities on the wire for Protocol The Capacity Profile MAY also be used to set priorities on the wire
Stacks supporting prioritization. Recommendations for use with DSCP for Protocol Stacks supporting prioritization. Recommendations for
are provided below for each profile; note that when a Connection is use with DSCP are provided below for each profile; note that when a
multiplexed, the guidelines in Section 6 of [RFC7657] apply. Connection is multiplexed, the guidelines in Section 6 of [RFC7657]
apply.
The following values are valid for the Capacity Profile: The following values are valid for the Capacity Profile:
Default: The application provides no information about its expected Default: The application provides no information about its expected
capacity profile. Transport system implementations that map the capacity profile. Transport system implementations that map the
requested capacity profile onto per-connection DSCP signaling requested capacity profile onto per-connection DSCP signaling
SHOULD assign the DSCP Default Forwarding [RFC2474] PHB. SHOULD assign the DSCP Default Forwarding [RFC2474] PHB.
Scavenger: The application is not interactive. It expects to send Scavenger: The application is not interactive. It expects to send
and/or receive data without any urgency. This can, for example, and/or receive data without any urgency. This can, for example,
be used to select protocol stacks with scavenger transmission be used to select protocol stacks with scavenger transmission
control and/or to assign the traffic to a lower-effort service. control and/or to assign the traffic to a lower-effort service.
Transport system implementations that map the requested capacity Transport system implementations that map the requested capacity
profile onto per-connection DSCP signaling SHOULD assign the DSCP profile onto per-connection DSCP signaling SHOULD assign the DSCP
Less than Best Effort [RFC8622] PHB. Less than Best Effort [RFC8622] PHB.
Low Latency/Interactive: The application is interactive, and prefers Low Latency/Interactive: The application is interactive, and prefers
loss to latency. Response time should be optimized at the expense loss to latency. Response time should be optimized at the expense
of bandwidth efficiency and delay variation when sending on this of delay variation and efficient use of the available capacity
connection. This can be used by the system to disable the when sending on this connection. This can be used by the system
coalescing of multiple small Messages into larger packets (Nagle's to disable the coalescing of multiple small Messages into larger
algorithm); to prefer immediate acknowledgment from the peer packets (Nagle's algorithm); to prefer immediate acknowledgment
endpoint when supported by the underlying transport; and so on. from the peer endpoint when supported by the underlying transport;
Transport system implementations that map the requested capacity and so on. Transport system implementations that map the
profile onto per-connection DSCP signaling without multiplexing requested capacity profile onto per-connection DSCP signaling
SHOULD assign a DSCP Assured Forwarding (AF41,AF42,AF43,AF44) without multiplexing SHOULD assign a DSCP Assured Forwarding
[RFC2597] PHB. Inelastic traffic that is expected to conform to (AF41,AF42,AF43,AF44) [RFC2597] PHB. Inelastic traffic that is
the configured network service rate could be mapped to the DSCP expected to conform to the configured network service rate could
Expedited Forwarding [RFC3246] or [RFC5865] PHBs. be mapped to the DSCP Expedited Forwarding [RFC3246] or [RFC5865]
PHBs.
Low Latency/Non-Interactive: The application prefers loss to latency Low Latency/Non-Interactive: The application prefers loss to latency
but is not interactive. Response time should be optimized at the but is not interactive. Response time should be optimized at the
expense of bandwidth efficiency and delay variation when sending expense of delay variation and efficient use of the available
on this connection. Transport system implementations that map the capacity when sending on this connection. Transport system
requested capacity profile onto per-connection DSCP signaling implementations that map the requested capacity profile onto per-
without multiplexing SHOULD assign a DSCP Assured Forwarding connection DSCP signaling without multiplexing SHOULD assign a
(AF21,AF22,AF23,AF24) [RFC2597] PHB. DSCP Assured Forwarding (AF21,AF22,AF23,AF24) [RFC2597] PHB.
Constant-Rate Streaming: The application expects to send/receive Constant-Rate Streaming: The application expects to send/receive
data at a constant rate after Connection establishment. Delay and data at a constant rate after Connection establishment. Delay and
delay variation should be minimized at the expense of bandwidth delay variation should be minimized at the expense of efficient
efficiency. This implies that the Connection may fail if the use of the available capacity. This implies that the Connection
desired rate cannot be maintained across the Path. A transport may fail if the desired rate cannot be maintained across the Path.
may interpret this capacity profile as preferring a circuit A transport may interpret this capacity profile as preferring a
breaker [RFC8084] to a rate-adaptive congestion controller. circuit breaker [RFC8084] to a rate-adaptive congestion
Transport system implementations that map the requested capacity controller. Transport system implementations that map the
profile onto per-connection DSCP signaling without multiplexing requested capacity profile onto per-connection DSCP signaling
SHOULD assign a DSCP Assured Forwarding (AF31,AF32,AF33,AF34) without multiplexing SHOULD assign a DSCP Assured Forwarding
[RFC2597] PHB. (AF31,AF32,AF33,AF34) [RFC2597] PHB.
High Throughput Data: The application expects to send/receive data Capacity-Seeking: The application expects to send/receive data at
at the maximum rate allowed by its congestion controller over a the maximum rate allowed by its congestion controller over a
relatively long period of time. Transport system implementations relatively long period of time. Transport system implementations
that map the requested capacity profile onto per-connection DSCP that map the requested capacity profile onto per-connection DSCP
signaling without multiplexing SHOULD assign a DSCP Assured signaling without multiplexing SHOULD assign a DSCP Assured
Forwarding (AF11,AF12,AF13,AF14) [RFC2597] PHB per Section 4.8 of Forwarding (AF11,AF12,AF13,AF14) [RFC2597] PHB per Section 4.8 of
[RFC4594]. [RFC4594].
The Capacity Profile for a selected protocol stack may be modified on The Capacity Profile for a selected protocol stack may be modified on
a per-Message basis using the Transmission Profile Message Property; a per-Message basis using the Transmission Profile Message Property;
see Section 7.5.8. see Section 7.5.8.
10.1.7. Bounds on Send or Receive Rate 10.1.7. Policy for using Multi-Path Transports
Name: max-send-rate / max-recv-rate Name: multipath-policy
Type: Numeric / Numeric Type: Enumeration
Default: -1 / -1 (unlimited, for both values)
Default: Handover
This property specifies the local policy of transferring data across
multiple paths between the same end hosts if Parallel Use of Multiple
Paths not set to Disabled (see Section 5.2.13). Possible values are:
Handover: The connection should only attempt to migrate between
different paths when the original path is lost or becomes
unusable. The actual thresholds to declare a path unusable are
implementation specific.
Interactive: The connection should attempt to use multiple paths in
parallel in order to minimize loss and delay. The actual strategy
is implementation specific.
Aggregate: The connection should attempt to use multiple paths in
parallel in order to maximize bandwidth and possibly overcome
bandwidth limitations of the individual paths. The actual
strategy is implementation specific.
Note that this is a local choice - the peer endpoint can choose a
different policy.
10.1.8. Bounds on Send or Receive Rate
Name: maxSendRate / maxRecvRate
Type: Numeric (with special value "Unlimited") / Numeric (with
special value "Unlimited")
Default: Unlimited / Unlimited
This property specifies an upper-bound rate that a transfer is not This property specifies an upper-bound rate that a transfer is not
expected to exceed (even if flow control and congestion control allow expected to exceed (even if flow control and congestion control allow
higher rates), and/or a lower-bound rate below which the application higher rates), and/or a lower-bound rate below which the application
does not deem a data transfer useful. It is given in bits per does not deem a data transfer useful. It is given in bits per
second. The special value -1 indicates that no bound is specified. second. The special value "Unlimited" indicates that no bound is
specified.
10.1.8. Read-only Connection Properties 10.1.9. Read-only Connection Properties
The following generic Connection Properties are read-only, i.e. they The following generic Connection Properties are read-only, i.e. they
cannot be changed by an application. cannot be changed by an application.
10.1.8.1. Maximum Message Size Concurrent with Connection Establishment 10.1.9.1. Maximum Message Size Concurrent with Connection Establishment
Name: zero-rtt-msg-max-len Name: zeroRttMsgMaxLen
Type: Integer Type: Integer
This property represents the maximum Message size that can be sent This property represents the maximum Message size that can be sent
before or during Connection establishment, see also Section 7.5.4. before or during Connection establishment, see also Section 7.5.4.
It is given in Bytes. It is given in Bytes.
10.1.8.2. Maximum Message Size Before Fragmentation or Segmentation 10.1.9.2. Maximum Message Size Before Fragmentation or Segmentation
Name: singular-transmission-msg-max-len Name: singularTransmissionMsgMaxLen
Type: Integer Type: Integer
This property, if applicable, represents the maximum Message size This property, if applicable, represents the maximum Message size
that can be sent without incurring network-layer fragmentation or that can be sent without incurring network-layer fragmentation or
transport layer segmentation at the sender. This property exposes transport layer segmentation at the sender. This property exposes
the Maximum Packet Size (MPS) as described in Datagram PLPMTUD the Maximum Packet Size (MPS) as described in Datagram PLPMTUD
[I-D.ietf-tsvwg-datagram-plpmtud]. [I-D.ietf-tsvwg-datagram-plpmtud].
10.1.8.3. Maximum Message Size on Send 10.1.9.3. Maximum Message Size on Send
Name: send-msg-max-len Name: sendMsgMaxLen
Type: Integer Type: Integer
This property represents the maximum Message size that can be sent This property represents the maximum Message size that can be sent
using a send operation. using a send operation.
10.1.8.4. Maximum Message Size on Receive 10.1.9.4. Maximum Message Size on Receive
Name: recvMsgMaxLen
Name: recv-msg-max-len
Type: Integer Type: Integer
This numeric property represents the maximum Message size that can be This numeric property represents the maximum Message size that can be
received. received.
10.2. TCP-specific Properties: User Timeout Option (UTO) 10.2. TCP-specific Properties: User Timeout Option (UTO)
These properties specify configurations for the User Timeout Option These properties specify configurations for the User Timeout Option
(UTO), in case TCP becomes the chosen transport protocol. (UTO), in case TCP becomes the chosen transport protocol.
Implementation is optional and of course only sensible if TCP is Implementation is optional and of course only sensible if TCP is
skipping to change at page 54, line 30 skipping to change at page 57, line 49
feature, it has to expose an interface to it to the application. feature, it has to expose an interface to it to the application.
Otherwise, the implementation might violate assumptions by the Otherwise, the implementation might violate assumptions by the
application, which could cause the application to fail. application, which could cause the application to fail.
All of the below properties are optional (e.g., it is possible to All of the below properties are optional (e.g., it is possible to
specify "User Timeout Enabled" as true, but not specify an Advertised specify "User Timeout Enabled" as true, but not specify an Advertised
User Timeout value; in this case, the TCP default will be used). User Timeout value; in this case, the TCP default will be used).
10.2.1. Advertised User Timeout 10.2.1. Advertised User Timeout
Name: tcp.user-timeout-value Name: tcp.userTimeoutValue
Type: Integer Type: Integer
Default: the TCP default Default: the TCP default
This time value is advertised via the TCP User Timeout Option (UTO) This time value is advertised via the TCP User Timeout Option (UTO)
[RFC5482] at the remote endpoint to adapt its own "Timeout for [RFC5482] at the remote endpoint to adapt its own "Timeout for
aborting Connection" (see Section 10.1.4) value accordingly. aborting Connection" (see Section 10.1.4) value accordingly.
10.2.2. User Timeout Enabled 10.2.2. User Timeout Enabled
Name: tcp.user-timeout Name: tcp.userTimeout
Type: Boolean Type: Boolean
Default: false Default: false
This property controls whether the UTO option is enabled for a This property controls whether the UTO option is enabled for a
connection. This applies to both sending and receiving. connection. This applies to both sending and receiving.
10.2.3. Timeout Changeable 10.2.3. Timeout Changeable
Name: tcp.user-timeout-recv Name: tcp.userTimeoutRecv
Type: Boolean Type: Boolean
Default: true Default: true
This property controls whether the "Timeout for aborting Connection" This property controls whether the "Timeout for aborting Connection"
(see Section 10.1.4) may be changed based on a UTO option received (see Section 10.1.4) may be changed based on a UTO option received
from the remote peer. This boolean becomes false when "Timeout for from the remote peer. This boolean becomes false when "Timeout for
aborting Connection" (see Section 10.1.4) is used. aborting Connection" (see Section 10.1.4) is used.
skipping to change at page 57, line 5 skipping to change at page 60, line 24
* Closed<> occurs when a Connection transitions to Closed state * Closed<> occurs when a Connection transitions to Closed state
without error. without error.
* InitiateError<> occurs when a Connection created with Initiate() * InitiateError<> occurs when a Connection created with Initiate()
transitions from Establishing state to Closed state due to an transitions from Establishing state to Closed state due to an
error. error.
* ConnectionError<> occurs when a Connection transitions to Closed * ConnectionError<> occurs when a Connection transitions to Closed
state due to an error in all other circumstances. state due to an error in all other circumstances.
The following diagram shows the possible states of a Connection and
the events that occur upon a transition from one state to another.
(*) (**)
Establishing -----> Established -----> Closed
| ^
| |
+-----------------------------------+
InitiateError<>
(*) Ready<>, ConnectionReceived<>, RendezvousDone<>
(**) Closed<>, ConnectionError<>
Figure 1: Connection State Diagram
The interface provides the following guarantees about the ordering of The interface provides the following guarantees about the ordering of
operations: operations:
* Sent<> events will occur on a Connection in the order in which the * Sent<> events will occur on a Connection in the order in which the
Messages were sent (i.e., delivered to the kernel or to the Messages were sent (i.e., delivered to the kernel or to the
network interface, depending on implementation). network interface, depending on implementation).
* Received<> will never occur on a Connection before it is * Received<> will never occur on a Connection before it is
Established; i.e. before a Ready<> event on that Connection, or a Established; i.e. before a Ready<> event on that Connection, or a
ConnectionReceived<> or RendezvousDone<> containing that ConnectionReceived<> or RendezvousDone<> containing that
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contributing text, e.g., on multicast. contributing text, e.g., on multicast.
16. References 16. References
16.1. Normative References 16.1. Normative References
[I-D.ietf-taps-arch] [I-D.ietf-taps-arch]
Pauly, T., Trammell, B., Brunstrom, A., Fairhurst, G., Pauly, T., Trammell, B., Brunstrom, A., Fairhurst, G.,
Perkins, C., Tiesel, P., and C. Wood, "An Architecture for Perkins, C., Tiesel, P., and C. Wood, "An Architecture for
Transport Services", Work in Progress, Internet-Draft, Transport Services", Work in Progress, Internet-Draft,
draft-ietf-taps-arch-06, 23 December 2019, draft-ietf-taps-arch-07, 9 March 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-taps-arch- <http://www.ietf.org/internet-drafts/draft-ietf-taps-arch-
06.txt>. 07.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<https://www.rfc-editor.org/info/rfc4941>. <https://www.rfc-editor.org/info/rfc4941>.
skipping to change at page 60, line 22 skipping to change at page 64, line 9
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
16.2. Informative References 16.2. Informative References
[I-D.ietf-taps-impl] [I-D.ietf-taps-impl]
Brunstrom, A., Pauly, T., Enghardt, T., Grinnemo, K., Brunstrom, A., Pauly, T., Enghardt, T., Grinnemo, K.,
Jones, T., Tiesel, P., Perkins, C., and M. Welzl, Jones, T., Tiesel, P., Perkins, C., and M. Welzl,
"Implementing Interfaces to Transport Services", Work in "Implementing Interfaces to Transport Services", Work in
Progress, Internet-Draft, draft-ietf-taps-impl-05, 4 Progress, Internet-Draft, draft-ietf-taps-impl-06, 9 March
November 2019, <http://www.ietf.org/internet-drafts/draft- 2020, <http://www.ietf.org/internet-drafts/draft-ietf-
ietf-taps-impl-05.txt>. taps-impl-06.txt>.
[I-D.ietf-taps-minset] [I-D.ietf-taps-minset]
Welzl, M. and S. Gjessing, "A Minimal Set of Transport Welzl, M. and S. Gjessing, "A Minimal Set of Transport
Services for End Systems", Work in Progress, Internet- Services for End Systems", Work in Progress, Internet-
Draft, draft-ietf-taps-minset-11, 27 September 2018, Draft, draft-ietf-taps-minset-11, 27 September 2018,
<http://www.ietf.org/internet-drafts/draft-ietf-taps- <http://www.ietf.org/internet-drafts/draft-ietf-taps-
minset-11.txt>. minset-11.txt>.
[I-D.ietf-taps-transport-security] [I-D.ietf-taps-transport-security]
Enghardt, T., Pauly, T., Perkins, C., Rose, K., and C. Enghardt, T., Pauly, T., Perkins, C., Rose, K., and C.
Wood, "A Survey of the Interaction Between Security Wood, "A Survey of the Interaction Between Security
Protocols and Transport Services", Work in Progress, Protocols and Transport Services", Work in Progress,
Internet-Draft, draft-ietf-taps-transport-security-11, 5 Internet-Draft, draft-ietf-taps-transport-security-12, 23
March 2020, <http://www.ietf.org/internet-drafts/draft- April 2020, <http://www.ietf.org/internet-drafts/draft-
ietf-taps-transport-security-11.txt>. ietf-taps-transport-security-12.txt>.
[I-D.ietf-tsvwg-datagram-plpmtud] [I-D.ietf-tsvwg-datagram-plpmtud]
Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and
T. Voelker, "Packetization Layer Path MTU Discovery for T. Voelker, "Packetization Layer Path MTU Discovery for
Datagram Transports", Work in Progress, Internet-Draft, Datagram Transports", Work in Progress, Internet-Draft,
draft-ietf-tsvwg-datagram-plpmtud-15, 24 February 2020, draft-ietf-tsvwg-datagram-plpmtud-22, 10 June 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-tsvwg- <http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-
datagram-plpmtud-15.txt>. datagram-plpmtud-22.txt>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>. <https://www.rfc-editor.org/info/rfc2474>.
[RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, [RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, "Assured Forwarding PHB Group", RFC 2597,
DOI 10.17487/RFC2597, June 1999, DOI 10.17487/RFC2597, June 1999,
skipping to change at page 63, line 33 skipping to change at page 67, line 26
Property objects (see Section 5.2) that are pre-configured with Property objects (see Section 5.2) that are pre-configured with
frequently used sets of properties. Implementations should at least frequently used sets of properties. Implementations should at least
offer short-hands to specify the following property profiles: offer short-hands to specify the following property profiles:
A.2.1. reliable-inorder-stream A.2.1. reliable-inorder-stream
This profile provides reliable, in-order transport service with This profile provides reliable, in-order transport service with
congestion control. An example of a protocol that provides this congestion control. An example of a protocol that provides this
service is TCP. It should consist of the following properties: service is TCP. It should consist of the following properties:
+-------------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+=========================+=========+ +=======================+=========+
| reliability | require | | reliability | require |
+-------------------------+---------+ +-----------------------+---------+
| preserve-order | require | | preserveOrder | require |
+-------------------------+---------+ +-----------------------+---------+
| congestion-control | require | | congestionControl | require |
+-------------------------+---------+ +-----------------------+---------+
| preserve-msg-boundaries | ignore | | preserveMsgBoundaries | ignore |
+-------------------------+---------+ +-----------------------+---------+
Table 2 Table 2
A.2.2. reliable-message A.2.2. reliable-message
This profile provides message-preserving, reliable, in-order This profile provides message-preserving, reliable, in-order
transport service with congestion control. An example of a protocol transport service with congestion control. An example of a protocol
that provides this service is SCTP. It should consist of the that provides this service is SCTP. It should consist of the
following properties: following properties:
+-------------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+=========================+=========+ +=======================+=========+
| reliability | require | | reliability | require |
+-------------------------+---------+ +-----------------------+---------+
| preserve-order | require | | preserveOrder | require |
+-------------------------+---------+ +-----------------------+---------+
| congestion-control | require | | congestionControl | require |
+-------------------------+---------+ +-----------------------+---------+
| preserve-msg-boundaries | require | | preserveMsgBoundaries | require |
+-------------------------+---------+ +-----------------------+---------+
Table 3 Table 3
A.2.3. unreliable-datagram A.2.3. unreliable-datagram
This profile provides unreliable datagram transport service. An This profile provides unreliable datagram transport service. An
example of a protocol that provides this service is UDP. It should example of a protocol that provides this service is UDP. It should
consist of the following properties: consist of the following properties:
+-------------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+=========================+=========+ +=======================+=========+
| reliability | ignore | | reliability | ignore |
+-------------------------+---------+ +-----------------------+---------+
| preserve-order | ignore | | preserveOrder | ignore |
+-------------------------+---------+ +-----------------------+---------+
| congestion-control | ignore | | congestionControl | ignore |
+-------------------------+---------+ +-----------------------+---------+
| preserve-msg-boundaries | require | | preserveMsgBoundaries | require |
+-------------------------+---------+ +-----------------------+---------+
| idempotent | true | | safely replayable | true |
+-------------------------+---------+ +-----------------------+---------+
Table 4 Table 4
Applications that choose this Transport Property Profile for latency Applications that choose this Transport Property Profile for latency
reasons should also consider setting the Capacity Profile Property, reasons should also consider setting the Capacity Profile Property,
see Section 10.1.6 accordingly and my benefit from controlling see Section 10.1.6 accordingly and my benefit from controlling
checksum coverage, see Section 5.2.7 and Section 5.2.8. checksum coverage, see Section 5.2.7 and Section 5.2.8.
Appendix B. Relationship to the Minimal Set of Transport Services for Appendix B. Relationship to the Minimal Set of Transport Services for
End Systems End Systems
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time value (Section 10.1.4). time value (Section 10.1.4).
* Timeout event when data could not be delivered for too long: * Timeout event when data could not be delivered for too long:
"ConnectionError" Event (Section 11). "ConnectionError" Event (Section 11).
* Suggest timeout to the peer: "TCP-specific Property: User Timeout" * Suggest timeout to the peer: "TCP-specific Property: User Timeout"
(Section 10.2). (Section 10.2).
* Notification of Excessive Retransmissions (early warning below * Notification of Excessive Retransmissions (early warning below
abortion threshold): "Notification of excessive retransmissions" abortion threshold): "Notification of excessive retransmissions"
property (Section 5.2.15). property (Section 5.2.16).
* Notification of ICMP error message arrival: "Notification of ICMP * Notification of ICMP error message arrival: "Notification of ICMP
soft error message arrival" property (Section 5.2.16). soft error message arrival" property (Section 5.2.17).
* Choose a scheduler to operate between streams of an association: * Choose a scheduler to operate between streams of an association:
"Connection Group Transmission Scheduler" property "Connection Group Transmission Scheduler" property
(Section 10.1.5). (Section 10.1.5).
* Configure priority or weight for a scheduler: "Priority * Configure priority or weight for a scheduler: "Priority
(Connection)" property (Section 10.1.3). (Connection)" property (Section 10.1.3).
* "Specify checksum coverage used by the sender" and "Disable * "Specify checksum coverage used by the sender" and "Disable
checksum when sending": "Corruption Protection Length" property checksum when sending": "Corruption Protection Length" property
(Section 7.5.6) and "Full Checksum Coverage on Sending" property (Section 7.5.6) and "Full Checksum Coverage on Sending" property
(Section 5.2.7). (Section 5.2.7).
* "Specify minimum checksum coverage required by receiver" and * "Specify minimum checksum coverage required by receiver" and
"Disable checksum requirement when receiving": "Required Minimum "Disable checksum requirement when receiving": "Required Minimum
Corruption Protection Coverage for Receiving" property Corruption Protection Coverage for Receiving" property
(Section 10.1.2) and "Full Checksum Coverage on Receiving" (Section 10.1.2) and "Full Checksum Coverage on Receiving"
property (Section 5.2.8). property (Section 5.2.8).
* "Specify DF" field and "Request not to bundle messages": the * "Specify DF" field and "Request not to bundle messages": the "No
"Singular Transmission" Message Property combines both of these Fragmentation" Message Property combines both of these requests,
requests, i.e. if a request not to bundle messages is made, this i.e. if a request not to bundle messages is made, this also turns
also turns off fragmentation (i.e., sets DF=1) in case of off fragmentation (i.e., sets DF=1) in the case of a protocol that
protocols that allow this (only UDP and UDP-Lite, which cannot allows this (only UDP and UDP-Lite, which cannot bundle messages
bundle messages anyway) (Section 7.5.9). anyway) (Section 7.5.9).
* Get max. transport-message size that may be sent using a non- * Get max. transport-message size that may be sent using a non-
fragmented IP packet from the configured interface: "Maximum fragmented IP packet from the configured interface: "Maximum
Message Size Before Fragmentation or Segmentation" property Message Size Before Fragmentation or Segmentation" property
(Section 10.1.8.2). (Section 10.1.9.2).
* Get max. transport-message size that may be received from the * Get max. transport-message size that may be received from the
configured interface: "Maximum Message Size on Receive" property configured interface: "Maximum Message Size on Receive" property
(Section 10.1.8.4). (Section 10.1.9.4).
* Obtain ECN field: "ECN" is a defined UDP(-Lite)-specific read-only * Obtain ECN field: "ECN" is a defined UDP(-Lite)-specific read-only
Message Property of the MessageContext object (Section 8.3.1). Message Property of the MessageContext object (Section 8.3.1).
* "Specify DSCP field", "Disable Nagle algorithm", "Enable and * "Specify DSCP field", "Disable Nagle algorithm", "Enable and
configure a 'Low Extra Delay Background Transfer'": as suggested configure a "Low Extra Delay Background Transfer"": as suggested
in Section 5.5 of [I-D.ietf-taps-minset], these transport features in Section 5.5 of [I-D.ietf-taps-minset], these transport features
are collectively offered via the "Capacity Profile" property are collectively offered via the "Capacity Profile" property
(Section 10.1.6). Per-Message control is offered via the "Message (Section 10.1.6). Per-Message control is offered via the "Message
Capacity Profile Override" property (Section 7.5.8). Capacity Profile Override" property (Section 7.5.8).
* Close after reliably delivering all remaining data, causing an * Close after reliably delivering all remaining data, causing an
event informing the application on the other side: this is offered event informing the application on the other side: this is offered
by the "Close" Action with slightly changed semantics in line with by the "Close" Action with slightly changed semantics in line with
the discussion in Section 5.2 of [I-D.ietf-taps-minset] the discussion in Section 5.2 of [I-D.ietf-taps-minset]
(Section 11). (Section 11).
skipping to change at page 68, line 18 skipping to change at page 72, line 21
* Notification that the stack has no more user data to send: * Notification that the stack has no more user data to send:
applications can obtain this information via the "Sent" Event applications can obtain this information via the "Sent" Event
(Section 7.3.1). (Section 7.3.1).
* Notification to a receiver that a partial message delivery has * Notification to a receiver that a partial message delivery has
been aborted: "ReceiveError" Event (Section 8.2.3). been aborted: "ReceiveError" Event (Section 8.2.3).
Authors' Addresses Authors' Addresses
Brian Trammell (editor) Brian Trammell (editor)
Google Google Switzerland GmbH
Gustav-Gull-Platz 1 Gustav-Gull-Platz 1
CH- 8004 Zurich CH- 8004 Zurich
Switzerland Switzerland
Email: ietf@trammell.ch Email: ietf@trammell.ch
Michael Welzl (editor) Michael Welzl (editor)
University of Oslo University of Oslo
PO Box 1080 Blindern PO Box 1080 Blindern
0316 Oslo 0316 Oslo
Norway Norway
Email: michawe@ifi.uio.no Email: michawe@ifi.uio.no
Theresa Enghardt Theresa Enghardt
TU Berlin Netflix
Marchstrasse 23 121 Albright Way
10587 Berlin Los Gatos, CA 95032,
Germany United States of America
Email: theresa@inet.tu-berlin.de Email: ietf@tenghardt.net
Godred Fairhurst Godred Fairhurst
University of Aberdeen University of Aberdeen
Fraser Noble Building Fraser Noble Building
Aberdeen, AB24 3UE Aberdeen, AB24 3UE
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
URI: http://www.erg.abdn.ac.uk/ URI: http://www.erg.abdn.ac.uk/
Mirja Kuehlewind Mirja Kuehlewind
Ericsson Ericsson
Ericsson-Allee 1 Ericsson-Allee 1
Herzogenrath Herzogenrath
Germany Germany
Email: mirja.kuehlewind@ericsson.com Email: mirja.kuehlewind@ericsson.com
Colin Perkins Colin Perkins
University of Glasgow University of Glasgow
skipping to change at page 69, line 28 skipping to change at page 73, line 30
Email: csp@csperkins.org Email: csp@csperkins.org
Philipp S. Tiesel Philipp S. Tiesel
TU Berlin TU Berlin
Einsteinufer 25 Einsteinufer 25
10587 Berlin 10587 Berlin
Germany Germany
Email: philipp@tiesel.net Email: philipp@tiesel.net
Chris Wood Christopher A. Wood
Apple Inc. Cloudflare
One Apple Park Way 101 Townsend St
Cupertino, California 95014, San Francisco,
United States of America United States of America
Email: cawood@apple.com Email: caw@heapingbits.net
Tommy Pauly Tommy Pauly
Apple Inc. Apple Inc.
One Apple Park Way One Apple Park Way
Cupertino, California 95014, Cupertino, California 95014,
United States of America United States of America
Email: tpauly@apple.com Email: tpauly@apple.com
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