Issue 124: SCA WSCB protocol conformance

Here are the reasons why I think we need to provide WSCB-specific 
targets and conformance statements:

1) We have relied on WS-* as our route to interoperability when it comes 
to SCA. This is one of the key reasons why WS Binding is required for 
any SCA runtime.

2) SCA WSCB is a WS-* protocol: it is SOAP/WSDL/Policy based providing a 
functionality on top of those specs.

3) One of the primary reasons for non-binding.sca is to talk to entities 
outside a domain. Just within a domain the need for non-binding.sca is 
weak at best; after all binding.sca is magic and you can do anything you 
want.

4) If we want services and references that use bi-directional interfaces 
to be usable from outside the SCA domain, and I'm arguing that we most 
certainly do, then it is important that we say exactly what is required 
from the implementer of the SCA WSCB protocol. A conformance criteria is 
more important for protocols than for systems (like SCA) that focus on 
portability and not interoperability). Experience from other protocol 
standards suggests that achieving interop on the wire is not easy and 
therefore anything that we do to provide clarity wrt conformance would 
greatly enhance interop.


One question that was asked on email/previous call was: what would my 
proposal be for resolving this issue. I would suggest something along 
the lines of:

a) add two new targets. Something like WSCB Service and WSCB Client.

b) refactor numbered stmts in section 5 to use these targets where 
appropriate. I don't think this would be too difficult. For example, 
BWS50005 current says:
"When the service implementation invokes the callback interface, it MUST 
use the Callback EPR from a request message that invoked the forward 
interface."
this would have to be changed to:
"When the --> **WSCB Service** <--- invokes the callback interface, it 
MUST use the Callback EPR from a request message that invoked the 
forward interface."

c) Add two new sections 6.x and 6.y for the two new targets (Section 6 
is about conformance) and in those section say " ... to conform the 
target MUST comply with all statements in Appendix C related to ..." 
similar to what we have done for other targets.

d) In section 6.2 SCA Runtime, change bullet 2 and 3 as follows:

     "2. The implementation MAY support the SCA Web Services Callback 
Protocol. If it does, it MUST be a compliant WSCB Service and a 
compliant WSCB Client.
     3. The implementation MAY support the SCA Web Services Callback 
Protocol in conjunction with WS-MakeConnection. If it does, it MUST be a 
complient WSCB Service and compliant WSCB Client and it MUST comply with 
the requirements of WS-MakeConnection."


-Anish
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