[oslc-core] Unrecognized content

[James Conallen]

In the current specification we have the statement:

   For OSLC Defined Resources, clients SHOULD assume that an OSLC Service
   will discard unknown property values. An OSLC Service MAY discard
   property values that are not part of the resource definition or Resource
   Shape known by the server.

We are running into a problem. When a client (in this case another
application server) PUTs an update to a resource that includes a 'link' to
another OSLC resource, and the server, at the time does not recognize the
link type, the link is not accepted, but a 200 OK is returned.  The server
returns a 200 OK, because it feels like it can ignore the unrecognized
link.  The client gets that 200 OK, and thinks that the link was
successfully added.

This doesn't feel right.  The only way a client can be sure that the PUT
worked as expected is to re-GET the resource and compare it to what it
expected to see (with the new link included), and maybe do a little looking
at ETags to make sure things haven't changed in between.

I guess the server could instead return a 400 Bad Request, and include in
the response the reason for not accepting the PUT.  But if the content that
was submitted really should just be ignored (i.e. is part of a future
version of the resource), then we don't want to abort the update.

The OSLC verbage does not provide any guidance as to what to do.  It would
be helpful if we had more detailed explanation of this statement in the
spec.


Thanks,

jim conallen
Rational Design Management (DM) Integration Architect, OSLC AM Lead
jconallen at us.ibm.com
Rational Software, IBM Software Group
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