Hi Jim,

a breaking change is the one that makes the client to either not being able to make a valid request,  parse the response or misinterpret the response, which otherwise
would work with the previous version of the extension.

It may be a change to format, syntax or semantics of an existing field,
removing or renaming or a field (both mandatory and optional - the latter would let client believe a value is not there which may have a semantic meaning). There are similar considerations related to path segments, request parameters and referrals.

What I notice now is that draft-ietf-regext-rdap-extensions-12 is in fact referring to a breaking change without really defining it. Only 5.4.2. is specifying what is a non-breaking change, which may imply that anything else is breaking. This may be fine, as long as 5.4.1 would tell it explicitly.

Kind Regards,
Pawel

On 11.06.26 14:39, Gould, James wrote:
Pawel,

I want to understand what you're defining as a non-backward compatible change in RDAP, since most of the members 
returned are optional and the protocol requires ignoring unrecognized members, which differs from a provisioning 
protocol.  Removing of a member should not break the client and renaming a member should similarly not break the 
client.  Changing of the extension identifier could break the client if they need the extension using the old extension 
identifier.  There is no way to foresee what will break a particular RDAP client.  The best that the protocol can do is 
to provide support for the version information and to enable the client to discover and to indicate what extension 
version is desired.  As pointed out previously, any RDAP extension that choses to use the point versioning type should 
include a normative reference to the versioning extension.  A client and server adding support for a point versioning 
extension needs to also add support for the versioning extension.  We can add language to the draft to reflect that 
requirement.  A similar case would be made if an extension decided to use another versioning type defined by the 
versioning extension (e.g., extension identifier versioning that Scott brought up; although no official name has been 
given), with the exception of the opaque versioning that is there for backward compatibility and as an option for those 
that chose that type going forward.  We may want to add relationships in the versioning extension for opaque version 
extensions to provide the visibility of changes, such as stating that "example1" is a successor of 
"example0" and that "example0" is a predecessor of "example1".  Would this he helpful?

In summary, the onboarding support of the versioning extension should be 
handled by the normative reference from new RDAP extensions that choose to use 
a type other than opaque versioning, so there should be no non-supporting 
clients of a point versioning RDAP extension.

Thanks,

-- JG James Gould Fellow Engineer [email protected] <applewebdata://13890C55-AAE8-4BF3-A6CE-B4BA42740803/[email protected]> 703-948-3271 12061 Bluemont Way Reston, VA 20190 Verisign.com <http://verisigninc.com/> On 6/11/26, 8:06 AM, "Pawel Kowalik" <[email protected] <mailto:[email protected]>> wrote: Hi Jim, the question is about a scenario: - existing extension in version 1 in production, no versioning deployed because not yet specified (applied to any of existing extensions to date) - the extension upgrades to version 2, which is not back-compatible with 1, assuming extension identifier does not change as you propose and argument How would this scenario work for a) a client which implements versioning draft vs. client which does not b) a server which implements versioning draft vs. client which does not It's a simple matrix 2x2. You may add additional example of the same if version 2 has a hard requirement for implementers to also implement versioning. Kind Regards, Pawel On 11.06.26 13:45, Gould, James wrote:
Andy,

Inclusion of some query/response examples for supporting and non-supporting 
clients are reflected in the following draft-ietf-regext-rdap-versioning 
figures:

1. Non-supporting - Figure 8: RDAP Domain Lookup Response with No Client 
Specified Versioning
2. Supporting - Figure 9: RDAP Domain Lookup Response with "point_ext1-0.1" 
Extension Version
3. Supporting - Figure 10: RDAP Domain Lookup Response with "point_ext1-0.1" and 
"opaque_ext2" Extension Versions

The only indication for the server whether the client is non-supporting or supporting is based on the 
inclusion of the Extension Versioning Request in Section 3.2. From an implementation perspective, a client 
will receive the "versioning_data" member that can be used by the supporting client to understand 
the extension versions included in the response and can be used for troubleshooting by a non-supporting 
client. The "versioning_data" member is in addition to the "rdapComformance" member and 
can be easily mapped based on indexing by the extension identifier.

Since we have no experience with an extension transition in RDAP, we can look 
to the experience with an extension transition in EPP, which has been done many 
times. In EPP, our implementation was to return a default version based on the 
latest supported version of an extension. If a client does not support the 
latest supported version, based on the login services, the server returns the 
earlier supported version of the extension. For RDAP, the server can return the 
latest supported version of the extension and allow for the client to specify 
an earlier version of an extension using the Extension Versioning Request 
(query parameter or media type parameter) in Section 3.2 of 
draft-ietf-regext-rdap-versioning. The /help can also be used for automatic 
discovery of the extension versioning or manually for troubleshooting issues. 
The discovery can be done infrequently (e.g., daily), since the RDAP servers 
don't change their extension versions very often.

I hope this helps.

Thanks,


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