Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

protocols and paths without requiring major changes to the application. <del> design explains the design principles behind the Transport </del> <ins> requirements explains the fundamental requirements for a Transport </ins> Services API.  These principles are intended to make sure that transport protocols can continue to be enhanced and evolve without <del> requiring too many changes by application developers. </del> <ins> requiring significant changes by application developers. </ins> concepts presents the Transport Services architecture diagram and defines the concepts that are used by both the API and


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

performance and functional characteristics; and it can communicate with different remote systems to optimize performance, robustness to failure, or some other metric.  Beyond these, if the API for the <del> system remains the same over time, new protocols and features could be added to the system's implementation without requiring changes in </del> <ins> system remains the same over time, new protocols and features can be added to the system's implementation without requiring changes in </ins> applications for adoption. <del> 3.1. </del> <ins> The normative requirements described here allow Transport Services APIs and Implementations to provide this functionlity without causing incompatibility or introducing security vulnerabilities.  The rest of this document describes the architecture non-normatively. </ins> <del> Functionality that is common across multiple transport protocols ought to be accessible through a unified set of API calls.  An application using a Transport Services API can implement logic for its basic use of transport networking (establishing the transport, and sending and receiving data) once, and expect that implementation to continue to function as the transports change. </del> <ins> 3.1. </ins> <del> As a baseline, any Transport Services API needs to allow access to the distilled minimal set of features offered by transport protocols </del> <ins> Any functionality that is common across multiple transport protocols SHOULD be made accessible through a unified set of Transport Services API calls.  As a baseline, any Transport Services API MUST allow access to the minimal set of features offered by transport protocols </ins> I-D.ietf-taps-minset. <ins> An application can specify constraints and preferences for the protocols, features, and network interfaces it will use via Properties.  A Transport Services API SHOULD offer Properties that are common to multiple transport protocols, in order to enable the system to appropriately select between protocols that offer equivalent features.  Similarly, a Transport Services API SHOULD offer Properties that are applicable to a variety of network layer interfaces and paths, in order to permit racing of different network paths without affecting the applications using the system.  Each Property is expected to have a default value. The default values for Properties SHOULD be selected to ensure correctness for the widest set of applications, while providing the widest set of options for selection.  For example, since both applications that require reliability and those that do not require reliability can function correctly when a protocol provides reliability, reliability ought to be enabled by default.  As another example, the default value for a Property regarding the selection of network interfaces ought to permit as many interfaces as possible. Applications using a Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, where the automated selection is constrained by the requirements and preferences expressed by the application. </ins> 3.2. There are applications that will need to control fine-grained details of transport protocols to optimize their behavior and ensure compatibility with remote systems.  A Transport Services system <del> therefore ought to also permit more specialized protocol features to be used.  The interface for these specialized options ought to be exposed differently from the common options to ensure flexibility. </del> <ins> therefore SHOULD permit more specialized protocol features to be used. </ins> A specialized feature could be required by an application only when using a specific protocol, and not when using others.  For example,


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

preference to use the User Timeout Option, communication would not fail when a protocol such as QUIC is selected. <del> Other specialized features, however, could be strictly required by an </del> <ins> Other specialized features, however, can be strictly required by an </ins> application and thus constrain the set of protocols that can be used. For example, if an application requires support for automatic handover or failover for a connection, only protocol stacks that


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

3.3. <del> The Transport Services API is envisioned as the abstract model for a family of APIs that share a common way to expose transport features and encourage flexibility.  The abstract API definition I-D.ietf- taps-interface describes this interface and how it can be exposed to application developers. Implementations that provide the Transport Services API I-D.ietf- taps-impl will vary due to system-specific support and the needs of the deployment scenario.  It is expected that all implementations of Transport Services will offer the entire mandatory API.  All implementations are expected to offer an API that is sufficient to use the distilled minimal set of features offered by transport protocols I-D.ietf-taps-minset, including API support for TCP and UDP transport.  However, some features provided by this API will not be functional in certain implementations.  For example, it is possible that some very constrained devices might not have a full TCP implementation beneath the API. To preserve flexibility and compatibility with future protocols, top- level features in the Transport Services API ought to avoid referencing particular transport protocols.  The mappings of these API features to specific implementations of each feature is explained in the I-D.ietf-taps-impl along with the implications of the feature on existing protocols.  It is expected that I-D.ietf-taps-interface will be updated and supplemented as new protocols and protocol features are developed. </del> <ins> A Transport Services implementation can select Protocol Stacks based on the Properties communicated by the application.  If two different Protocol Stacks can be safely swapped, or raced in parallel (see racing), then they are considered to be "equivalent".  Equivalent Protocol Stacks are defined as stacks that can provide the same transport properties and interface expectations as requested by the application. The following two examples show non-equivalent Protocol Stacks: If the application requires preservation of message boundaries, a Protocol Stack that runs UDP as the top-level interface to the application is not equivalent to a Protocol Stack that runs TCP as the top-level interface.  A UDP stack would allow an application to read out message boundaries based on datagrams sent from the remote system, whereas TCP does not preserve message boundaries on its own, but needs a framing protocol on top to determine message boundaries. If the application specifies that it requires reliable transmission of data, then a Protocol Stack using UDP without any reliability layer on top would not be allowed to replace a Protocol Stack using TCP. The following example shows equivalent Protocol Stacks: If the application does not require reliable transmission of data, then a Protocol Stack that adds reliability could be regarded as an equivalent Protocol Stack as long as providing this would not conflict with any other application-requested properties. To ensure that security protocols are not incorrectly swapped, Transport Services systems MUST only select Protocol Stacks that meet application requirements (I-D.ietf-taps-transport-security).  Systems SHOULD only race Protocol Stacks where the transport security protocols within the stacks are identical.  Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols.  A Transport Services system MAY allow applications to explicitly specify that fallback to a specific other version of a protocol is allowed, e.g., to allow fallback to TLS 1.2 if TLS 1.3 is not available. 3.4. </ins> It is important to note that neither the Transport Services API I- D.ietf-taps-interface nor the Implementation document I-D.ietf-taps- impl define new protocols or protocol capabilities that affect what is communicated across the network.  Use of a Transport Services <del> system does not require that a peer on the other side of a connection </del> <ins> system MUST NOT require that a peer on the other side of a connection </ins> uses the same API or implementation.  A Transport Services system <del> acting as a connection initiator can communicate with any existing system that implements the transport protocol(s) selected by the Transport Services system.  Similarly, a Transport Services system acting as a listener can receive connections for any protocol that is supported by the system from existing initiators that implement the protocol, independent of whether the initiator uses Transport Services as well or not. </del> <ins> acting as a connection initiator is able to communicate with any existing system that implements the transport protocol(s) and all the required properties selected by the Transport Services system. Similarly, a Transport Services system acting as a listener can receive connections for any protocol that is supported by the system from existing initiators that implement the protocol, independent of whether the initiator uses a Transport Services system or not. In normal use, a Transport Services system SHOULD result in consistent protocol and interface selection decisions for the same network conditions given the same set of Properties.  This is intended to provide predictable outcomes to the application using the API. </ins> 4.


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

4.2.3. <del> The Transport Services architecture defines a mechanism that allows applications to easily make use of various network paths and Protocol Stacks without requiring major changes in application logic.  In some cases, changing which Protocol Stacks or network paths are used will require updating the preferences expressed by the application that uses the Transport Services system.  For example, an application can enable the use of a multipath or multistreaming transport protocol by modifying the properties in its Pre-Connection configuration.  In some cases, however, the Transport Services system will be able to automatically change Protocol Stacks without an update to the application, either by selecting a new stack entirely, or by racing multiple candidate Protocol Stacks during connection establishment. This functionality in the API can be a powerful driver of new protocol adoption, but needs to be constrained carefully to avoid unexpected behavior that can lead to functional or security problems. If two different Protocol Stacks can be safely swapped, or raced in parallel (see racing), then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the following criteria: Both stacks MUST offer the interface requested by the application for connection establishment and data transmission.  For example, if an application requires preservation of message boundaries, a Protocol Stack that runs UDP as the top-level interface to the application is not equivalent to a Protocol Stack that runs TCP as the top-level interface.  A UDP stack would allow an application to read out message boundaries based on datagrams sent from the remote system, whereas TCP does not preserve message boundaries on its own, but needs a framing protocol on top to determine message boundaries. Both stacks MUST offer the transport services that are requested by the application.  For example, if an application specifies that it requires reliable transmission of data, then a Protocol Stack using UDP without any reliability layer on top would not be allowed to replace a Protocol Stack using TCP.  However, if the application does not require reliability, then a Protocol Stack that adds reliability could be regarded as an equivalent Protocol Stack as long as providing this would not conflict with any other application-requested properties. Both stacks MUST offer security protocols and parameters as requested by the application I-D.ietf-taps-transport-security. Security features and properties, such as cryptographic algorithms, peer authentication, and identity privacy vary across security protocols, and across versions of security protocols. Protocol equivalence ought not to be assumed for different protocols or protocol versions, even if they offer similar application configuration options.  To ensure that security protocols are not incorrectly swapped, Transport Services systems SHOULD only automatically generate equivalent Protocol Stacks when the transport security protocols within the stacks are identical. Specifically, a Transport Services system would consider protocols identical only if they are of the same type and version.  For example, the same version of TLS running over two different transport Protocol Stacks are considered equivalent, whereas TLS 1.2 and TLS 1.3 RFC8446 are not considered equivalent.  However, Transport Services systems MAY allow applications to indicate that they consider two different transport protocols equivalent, e.g., to allow fallback to TLS 1.2 if TLS 1.3 is not available. 4.2.4. </del> By default, stored properties of the implementation, such as cached protocol state, cached path state, and heuristics, may be shared (e.g. across multiple connections in an application).  This provides


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

D.ietf-taps-transport-security. As described above in equivalence, if a Transport Services system <del> races between two different Protocol Stacks, both SHOULD use the same security protocols and options.  However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. </del> <ins> races between two different Protocol Stacks, both need to use the same security protocols and options.  However, a Transport Services system can race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. </ins> Applications need to ensure that they use security APIs appropriately.  In cases where applications use an interface to


Question:
This proposal consolidates normative language into the section on design principles (now requirements), using the suggestions in .
Please review the latest updates!
Early art-art review of draft-ietf-taps-architecture My first observation and request is that the group rethink the separation of the architecture and interface documents. It is a warning-sign that the interface document is a normative reference for the architecture document. As the documents are currently constructed, a new reader cannot grasp the architecture without inferring some of it through reading the interface. Consider reformulating the architecture document as an overview - introduce principles, concepts, and terminology, but don't attempt to be normative. (There are signs that this may already be, or have been, a path the document was being pushed towards). If nothing else, rename it, and acknowledge that the actual architecture is specified using the interface definition. Note that the first sentence of the Overview in the interface document also highlights the current structural problem.
I don't entirely agree with this ART-ART comment: I think I might well agree with moving more of the description to this Arch document, but as discussed before, I also think it useful here to set the actual requirements for the architecture, and to define the architecture. It may need to be much clearer that this architecture consists of more the API.
For completeness, this is the first statement of the interface document review: This document reads fairly well. I have some structural concerns (see the early review of the architecture document). In particular I think this document contains the actual definition of the architecture and some of that is inferential.
Discussion at September 2021 interim: pass through this document with a view toward making it a high level introduction, not an architecture definition: "An Introduction to the Transport Services Architecture". remove normative language from this document (moving it to API, where necessary). move details not useful in a high level intro to API.
I disagree with this conclusion at first pass—we did a specific analysis and pass on this over a year ago, with PR . The normative language and the standards-track aspect was very intentional and something the WG had consensus on. The point is that the API is a specific incarnation of the TAPS architecture, but there are overarching architectural properties that go beyond a specific abstract API.
I completely agree with Tommy here, and recommend we fix this in . We should also of course check for any stray text or missing concepts. I think it would also be useful to somehow better explain that in figure 3 the API function is ONE part of the system.
See linked PR first please to see if this resolves this?
A PR was merged that addressed important text issues with separation of requirements and overview, and should more clearly set out that the requirements are for the system. The question of whether the overall TAPS systems requirements belong in this ID; the API; or a separate RFC needs some discussion based on the review, before this can be closed.
Many good text improvements in the PR NAME but I noticed two smaller updates in the PR that I think were incorrect. Fixed in
The review comment showed were many places where the wording of architecture can be improved. There are some high level principles that I think should remain in the architecture document. The decision in today's interim is to review the architecture to get this more into a shape that is valuable as a reference, and then check the updated draft.
I now suggest the issues are addressed and we close this issue without moving text between documents
I agree with that; closing.
Overall review: I think we need to keep the normative language for the key features that differentiate the API. I'd really like to use REQUIRED, RECOMMENDED, rather MUST and SHOULD - because these are not protocol operation requirements, but are implementation requirements to conform. This includes requirements based on Minset - where the WG dervied this API: This is after all why the WG worked on Minset as the basis of the API. I suggest we group all the requirements on architecture as short one or two sentence blocks (preferably as a bullet or definition list) collected into a single subsection, so they are easy to find and read and we say that these are the key architectural requirements. We insert this new requirements text either their own section, or in section 1.3 (although I am open to other places where we can call-out the architectural requirements). The following are key requirements, that define the TAPS architecture: It is RECOMMENDED that functionality that is common across multiple transport protocols is made accessible through a unified set of TAPS interface calls. As a baseline, a Transport Services system interface is REQUIRED to allow access to the minimal set of features offered by transport protocols {{?I-D.ietf-taps-minset}}. A Transport Services system automates the selection of protocols and features and network, based on a set of Properties supplied through the TAPS interface. It is RECOMMENDED that a Transport Services system offers Properties that are common to multiple transport protocols. Specifying common Properties enables a system to appropriately select between protocols that offer equivalent features. This design permits evolution of the transport protocols and functions without affecting the programs using the system. Specifying common Properties enables a Transport Services system to appropriately select an appropriate network interface. It is RECOMMENDED that a system offers Properties that are common to a variety network layer interfaces and paths. This design permits racing of different network paths without affecting the programs using the system. Applications using the Transport Services system interface are REQUIRED to be robust to the automated selection provided by the system, including the possibility to express requirements and preferences that constrain the choices that can be made by the system. If two different Protocol Stacks can be safely swapped, or raced in parallel (see Section 4.2.2), by the Transport Services system then they are considered to be "equivalent". Equivalent Protocol Stacks need to meet the requirements for racing specified in section XX. Applications using a Transport Services system MAY explicitly require or prevent the use of specific transport features (and transport protocols) and XXXinterfaces using the "REQUIRED" and "PROHIBIT" preferences. This allows an application to constrain the set of protocols and features that will be selected for the transport service. It is RECOMMENDED that the default usage by applications does not necessarily restrict this selection, so that the system can make informed choices (e.g., based on the availability of interfaces or set of transport protocols available for the specified remote endpoint). When a Transport Services system races between two different Protocol Stacks, both SHOULD use the same security protocols and options. However, a Transport Services system MAY race different security protocols, e.g., if the application explicitly specifies that it considers them equivalent. Transport Services systems MUST NOT automatically fall back from secure protocols to insecure protocols, or to weaker versions of secure protocols. A Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. It is RECOMMENDED that in normal use, a Transport Services system is designed so that all selection decisions result in consistent choices for the same network conditions when they have the same set of preferences. This is intended to provide predictable outcomes to the application using the transport service. I would then suggest to use lower case within other parts of the document - except were pointed to from here, (we could refer to the requirements subsection, if we thought necessary).
for discussion at the interim, but IMO we could start the interim with a PR based on these suggestions and work from there.
I suspect that we need more protocol-specific properties to be able to talk to various kinds of native protocol peers (other than TCP and UDP: these should already work fine with what we have, I believe). A concrete example: we're hiding stream numbers. In NEAT, we needed to make them configurable though, because we wanted a NEAT client to be able to talk to a native SCTP server, where an application may expect certain type of data to arrive via a certain stream number. I suspect that we may need something similar for a QUIC peer. Should we address this? (I'd say yes) How .. is it a protocol-specific (per-Message) property? (I'd say yes... and perhaps a per-Connection property too, with text explaining that the per-Message one automatically becomes the Connection default unless otherwise specified) What other such things are we missing... what other expectations may e.g. a native QUIC or SCTP application have that we just cannot fulfil with our current system?

QUIC, and applications ought not to use private keys intended for server authentication as keys for client authentication. <del> Moreover, Transport Services systems MUST NOT automatically fall back </del> <ins> Moreover, Transport Services systems must not automatically fall back </ins> from secure protocols to insecure protocols, or to weaker versions of <del> secure protocols.  For example, if an application requests a specific version of TLS, but the desired version of TLS is not available, its connection will fail.  Applications are thus responsible for implementing security protocol fallback or version fallback by creating multiple Transport Services Connections, if so desired. Alternatively, a Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. </del> <ins> secure protocols (see equivalence).  For example, if an application requests a specific version of TLS, but the desired version of TLS is not available, its connection will fail.  Applications are thus responsible for implementing security protocol fallback or version fallback by creating multiple Transport Services Connections, if so desired.  Alternatively, a Transport Services system MAY allow applications to specify that fallback to a specific other version of a protocol is allowed. </ins>


Question:
In the API doc sec 5 says. "Message Framers (see Section 10), if required, should be added to the Preconnection during pre-establishment." Should this be SHOULD or even MUST? If SHOULD is correct I think we need to say slightly more about when it makes sense to add a framer later.
I think it should be "can be added..."; not normative, just descriptive of fact.
Can we start with the "If' perhaps... "If messages frames are to be used, they MUST be added to the Preconnection during pre-establishment."?

Transport Properties MUST always be specified while security parameters are OPTIONAL. <del> Message Framers (see framing), if required, should be added to the </del> <ins> If Message Framers are used (see framing), they MUST be added to the </ins> Preconnection during pre-establishment. 5.1.


Question:
I actually really like: "Simultaneous" and "Staggered" as descriptive terms that avoid the question of "delaying".
Opening this to follow up on a comment by NAME on that is now closed. "Simultaneous" and "Staggered" would be better names than "Immediate" and "Delayed". Just from these terms, I would normally think that "Immediate" means to start racing right away, whereas "Delayed" means that nothing would happen for some time. So these two terms are slightly misleading in my opinion.)
I agree this would be an improvement.
In Section 4.2.1., I didn't really understand what "immediate" means from the text. I think it just needs one sentence.
lgtm (side note - nothing blocking, this is just an idea: to me, "Simultaneous" and "Staggered" would be better names than "Immediate" and "Delayed". Just from these terms, I would normally think that "Immediate" means to start racing right away, whereas "Delayed" means that nothing would happen for some time. So these two terms are slightly misleading in my opinion.)Looks good, thanks! I will close this and open a separate issue for the naming.

4.2.1. <del> Immediate, or simultaneous, racing should be avoided by implementations.  This approach can consume network resources and establish state that will not be used. </del> <ins> Immediate racing is when multiple alternate branches are started without waiting for any one branch to make progress before starting the next alternative.  This means the attempts are effectively simultaneous.  Immediate racing should be avoided by implementations, since it consumes extra network resources and establishes state that might not be used. </ins> 4.2.2.


Question:
NAME 7df2d9c should address this
To we need multiple local and remote candidates. Should this be represented as either: 1) taking two lists of objects; or 2) as two objects each with multiple addresses, ports, etc. I suggest option 1, since this makes it easier to resolve a to multiple preconnections, for NAT binding discovery. Relates to but with also different types of endpoint.
I like option 1 because it contains complexity.
See this email thread: URL Copy + pasting a relevant part from an email from NAME To me at least, it wasn't clear from the text that rendezvous() would kick off ICE-style probing. It's kind of obvious (when else would it happen?), but I think it would be good for the draft to spell this out.
modulo the do-we-want-to-bind-tightly-to-ICE question... Dear all, I know way too little about rendezvous mechanisms, so I may get this completely wrong - please bear with me! It may be that I describe an issue that’s a non-issue. But, if I do understand this right, maybe that’s something which needs fixing? Ok, here it goes… Our current Rendezvous text in the API draft says the following: "The Rendezvous() Action causes the Preconnection to listen on the Local Endpoint for an incoming Connection from the Remote Endpoint, while simultaneously trying to establish a Connection from the Local Endpoint to the Remote Endpoint. This corresponds to a TCP simultaneous open, for example.” Now, if an application chooses unreliable data transmission, it may get SCTP with partial reliability, or it may (in the future) get QUIC with datagrams, or whatever… and then, the protocol may be able to do what’s needed (something similar to a simultaneous open). However, in case of UDP: Listening is quite okay, “simultaneously trying to establish a Connection” really means nothing - no packet will be sent. I believe that applications doing this over UDP will implement their own “SYN”-type signal for this - but then it’s up to the application, which, over TAPS, would need to: create a passive connection, send a Message from that same connection, i.e. using the same local address and port (I believe?) - which is a matter of configuring the local endpoint, and doable if the underlying transport system can pull it off. I think there’s nothing in our API preventing an application from doing this. If all of the above is correct, the problem that I see is that an application may ask for unreliable transmission, and then have one case in which calling “Rendezvous” is the right thing to do, and another case in which it is not - so it would need to be able to distinguish between these two cases: is it a protocol with Rendezvous-capability, or do I have to do it myself. Maybe, in case of UDP, the call to Rendezvous should just fail, and our text should say that Rendezvous failing would inform the application that it would have to implement it by itself, by issuing Listen and then sending a Message to the peer. Thoughts? Am I completely off track, or is this something that needs a text fix? Cheers, Michael

The Rendezvous() Action causes the Preconnection to listen on the Local Endpoint for an incoming Connection from the Remote Endpoint, <del> while simultaneously trying to establish a Connection from the Local Endpoint to the Remote Endpoint.  This corresponds to a TCP simultaneous open, for example. </del> <ins> while also simultaneously trying to establish a Connection from the Local Endpoint to the Remote Endpoint. If there are multiple Local Endpoints or Remote Endpoints configured, then initiating a rendezvous action will systematically probe the reachability of those endpoints following an approach such as that used in Interactive Connectivity Establishment (ICE) RFC5245. If the endpoints are suspected to be behind a NAT, Rendezvous() can be initiated using Local and Remote Endpoints that support a method of discovering NAT bindings such as Session Traversal Utilities for NAT (STUN) RFC8489 or Traversal Using Relays around NAT (TURN) RFC5766.  In this case, the Local Endpoint will resolve to a mixture of local and server reflexive addresses.  The Resolve() action on the Preconnection can be used to discover these bindings: The Resolve() call returns a list of Preconnection Objects, that represent the concrete addresses, local and server reflexive, on which a Rendezvous() for the Preconnection will listen for incoming Connections.  These resolved Preconnections will share all other Properties with the Preconnection from which they are derived, though some Properties may be made more-specific by the resolution process. An application that uses Rendezvous() to establish a peer-to-peer connection in the presence of NATs will configure the Preconnection object with a Local Endpoint that supports NAT binding discovery.  It will then Resolve() on that endpoint, and pass the resulting list of candidate local addresses to the peer via a signalling protocol, for example as part of an ICE RFC5245 exchange within SIP RFC3261 or WebRTC RFC7478.  The peer will, via the same signalling channel, return the remote endpoint candidates.  These remote endpoint candidates are then configured on the Preconnection, allowing the Rendezvous() Action to be initiated. </ins> The Rendezvous() Action returns a Connection object.  Once Rendezvous() has been called, any changes to the Preconnection MUST


Question:
(well, the priority framework is still confusing, this PR makes it clear that that is intentional, and why)
Martin (I think) said that he'd check this offline after the Sep 11 interim.
At 8.1.2 you say lower values have higher priorities for connPrio. But later, at msgPrio, higher values have higher priority, and in the examples where you speak of the interaction of connPrio and msgPrio, you imply that higher means higher for both properties. Please check for consistency and clarify.
Lower values having higher priorities for connPrio is a remnant that we must have missed when we flipped this, e.g. PR which I don't know... too many iterations have mangled the text.
Aha, now I see what happened: following some more PRs, also , in PR , NAME re-introduced some text saying that sends on Connections with lower-priority values will be prioritized over sends on Connections with a higher-priority value. This reverses the logic for some part of the text - I suspect that NAME (very understandably!) forgot what happened and this created this mix. We have been editing these documents for way too long!
I'm not sure the priority framework really fits together. Sec 6.4 says we 'should' do something that sounds like WFQ, but 7.1.5 allows the application to decide what happens. Meanwhile message priority suggests a strict priority-based scheduler. Meanwhile, in sec 8.1.3.2 "Note that this property is not a per-message override of the connection Priority - see Section 7.1.3. Both Priority properties may interact, but can be used independently and be realized by different mechanisms." At the risk of overindexing on a partly-baked draft in httpbis, how would I implement strict priority of HTTP/3 streams over a taps API that implements QUIC? Would I need to request strict priority in both connection priority and message priority? Or I guess connection priority would be sufficient?
We seem comfortable with the mechanisms in the API, but we should have more text connecting the various sections explaining priority.
My comment concerned "7.1.3. Priority (Connection)", my thought was this just influences the sender-side to control queuing within a connection group. If so, if it worth calling this property "Group Priority" and explain this is sender-side?
I find the priority framework perhaps overspecified at the connection level and underspecified at the message level, with the interaction between the two left explicitly unstated. I would almost rather see the priority type and meaning left completely implementation-specific; otherwise, my suspicion is that someone will write an application using numeric priorities, declare victory when it works fine on one platform, and not understand that the behavior is not universal. In general, I think if TAPS is going to produce a consistent, easily-understandable, and portable API, it needs to stick to easily-understood abstractions. Message-level priority is sort of like the TCP URG mechanism (though better specified and more useful, for sure), but I'm thinking urgent messages sent explicitly out-of-band (e.g., new Connection) with implementation-specific QoS will produce more consistent, predictable, and understandable outcomes in the pessimal case.
Ok for me (and thanks for doing this!)Some nits, but I believe this addresses my concerns in the issue.

other, and become part of a Connection Group.  Calling Clone on any of these Connections adds another Connection to the Connection Group, and so on.  "Entangled" Connections share all Connection Properties <del> except "Priority (Connection)", see conn-priority.  Like all other Properties, Priority is copied to the new Connection when calling Clone(), but it is not entangled: Changing Priority on one Connection does not change it on the other Connections in the same Connection Group. </del> <ins> except "Connection Priority", see conn-priority.  Like all other Properties, Connection Priority is copied to the new Connection when calling Clone(), but it is not entangled: Changing Connection Priority on one Connection does not change it on the other Connections in the same Connection Group. </ins> It is also possible to check which Connections belong to the same Connection Group.  Calling GroupedConnections() on a specific


Question:
(well, the priority framework is still confusing, this PR makes it clear that that is intentional, and why)
Martin (I think) said that he'd check this offline after the Sep 11 interim.
At 8.1.2 you say lower values have higher priorities for connPrio. But later, at msgPrio, higher values have higher priority, and in the examples where you speak of the interaction of connPrio and msgPrio, you imply that higher means higher for both properties. Please check for consistency and clarify.
Lower values having higher priorities for connPrio is a remnant that we must have missed when we flipped this, e.g. PR which I don't know... too many iterations have mangled the text.
Aha, now I see what happened: following some more PRs, also , in PR , NAME re-introduced some text saying that sends on Connections with lower-priority values will be prioritized over sends on Connections with a higher-priority value. This reverses the logic for some part of the text - I suspect that NAME (very understandably!) forgot what happened and this created this mix. We have been editing these documents for way too long!
I'm not sure the priority framework really fits together. Sec 6.4 says we 'should' do something that sounds like WFQ, but 7.1.5 allows the application to decide what happens. Meanwhile message priority suggests a strict priority-based scheduler. Meanwhile, in sec 8.1.3.2 "Note that this property is not a per-message override of the connection Priority - see Section 7.1.3. Both Priority properties may interact, but can be used independently and be realized by different mechanisms." At the risk of overindexing on a partly-baked draft in httpbis, how would I implement strict priority of HTTP/3 streams over a taps API that implements QUIC? Would I need to request strict priority in both connection priority and message priority? Or I guess connection priority would be sufficient?
We seem comfortable with the mechanisms in the API, but we should have more text connecting the various sections explaining priority.
My comment concerned "7.1.3. Priority (Connection)", my thought was this just influences the sender-side to control queuing within a connection group. If so, if it worth calling this property "Group Priority" and explain this is sender-side?
I find the priority framework perhaps overspecified at the connection level and underspecified at the message level, with the interaction between the two left explicitly unstated. I would almost rather see the priority type and meaning left completely implementation-specific; otherwise, my suspicion is that someone will write an application using numeric priorities, declare victory when it works fine on one platform, and not understand that the behavior is not universal. In general, I think if TAPS is going to produce a consistent, easily-understandable, and portable API, it needs to stick to easily-understood abstractions. Message-level priority is sort of like the TCP URG mechanism (though better specified and more useful, for sure), but I'm thinking urgent messages sent explicitly out-of-band (e.g., new Connection) with implementation-specific QoS will produce more consistent, predictable, and understandable outcomes in the pessimal case.
Ok for me (and thanks for doing this!)Some nits, but I believe this addresses my concerns in the issue.

Attempts to clone a Connection can result in a CloneError: <del> The Connection Property "Priority" operates on entangled Connections as in msg-priority: when allocating available network capacity among Connections in a Connection Group, sends on Connections with higher Priority values will be prioritized over sends on Connections with lower Priority values.  A transport system implementation should, if possible, assign each Connection the capacity share (M-N) x C / M, where N is the Connection's Priority value, M is the maximum Priority value used by all Connections in the group and C is the total available capacity.  However, this Priority setting is purely advisory, and provides no guarantees about the way capacity is shared.  Each implementation is free to implement a way to share capacity that it sees fit. </del> <ins> The Connection Priority Connection Property operates on entangled Connections using the same approach as in msg-priority: when allocating available network capacity among Connections in a Connection Group, sends on Connections with lower Priority values will be prioritized over sends on Connections with higher Priority values.  Capacity will be shared among these Connections according to the Connection Group Transmission Scheduler property (conn- scheduler).  See priority-in-taps for more. </ins> 7.