Comment on Evolution of XML protocol requirements

Regarding R702:

R702 Requirement for Evolution
              The XP specification must define the concept of protocol
evolution and define a mechanism or
              mechanisms for identifying XP revisions. This mechanism or
mechanisms must ensure that an XP
              processor, by simple inspection of an XP envelope, may
determine whether or not the envelope is
              compatible with its processing ability. The specification
must define the concepts of backwards
              compatible and backwards incompatible evolution.

This is good as the envelope needs versioning. However, the follow-on
issues should also be considered:

-> Upon failure of envelope version support, there should be a consistent
error indicating so. This then
leads to the question of "what version of envelope should that error be
contained in?" The following
question surfaces: "What versions do you support?".

Not to step into a solution, but to add some experience, these issues have
been addressed in other
efforts through definition of both Versioned and NonVersioned messages and
Standard Errors.
I would suggest the following modification to R702 to take into account
more comprehensive
Versioning:

"............The specification must define the concepts of backwards
compatible and backwards incompatible
evolution through a consistent mechanism over time that encompasses
incompatable version detection
and discovery of supported XP versions."

Thanks,
Scott Hinkelman, Senior Software Engineer
XML Industry Enablement
IBM e-business Standards Strategy
512-823-8097 (TL 793-8097) (Cell: 512-940-0519)
srh@us.ibm.com, Fax: 512-838-1074

Received on Wednesday, 10 January 2001 12:02:59 UTC