RE: [sca-bindings] ISSUE-22: Callbacks for binding.ws

One difference is that I’m assuming
that we want to avoid introducing new SOAP headers into the WS-* world (let me
know if you disagree).  The approach that we’ve adopted for JMS
includes the introduction of a new “scaCallbackQueue” header (which
is called a user property in JMS).  If we want to avoid creating a new
SOAP header, then I think we need to figure out how to use headers that have
already been defined in some WS-* standard and use it in a way that is in
keeping with the standard.

 

Michael

 

From: Eric Johnson
[mailto:] 

Sent: Friday, February 22, 2008
4:50 PM

To: Michael Rowley

Cc: OASIS Bindings; Anish
Karmarkar; Jim Marino

Subject: Re: [sca-bindings]
ISSUE-22: Callbacks for binding.ws

 

Am I missing something
here?

Suppose for a moment that you ignore that "anonymous" reply channel
in HTTP, and every message uses WS-Addressing for a response (although
potentially it uses the "anonymous" channel).

How is this problem of callbacks over WS binding different from the four (five?
six?) week effort on JMS that we (but mostly Simon H.) went through trying to
figure out how to handle the JMSReplyTo header, depending on MEP, and
callbacks?  With JMS there is a clear upside to using the JMSReplyTo
header, in that it is already a "Destination", thus overcoming some
potential limitations.

If this is the same problem, does it deserve a solution that follows the same
pattern?  Or, is it a characteristically different problem (as I think it
is), in that there isn't any "blessed" "reply" header that
is any more special than any other.

-Eric.

Michael Rowley wrote: 

 

I’d like to get
this topic started.  I’ve narrowed the subject line from the
original Issue 22 title, since I’d like this particular thread to be on
how callbacks could be handled in the WS-* world.  We can handle
conversations and other bindings on other threads.  

 

First, I’ll assume
that we will try to use WS-Addressing, if possible.  

 

My first thought is that
it would be preferable to be able to leverage the ws-ReplyTo field, since I
believe that it should be possible to distinguish replies from callbacks, and I
also believe that callbacks should go to the same place that replies would go
to.  I have a vague recollection that Anish preferred the use of
<wsa:from> rather than <wsa:replyTo> for passing callback ID
information.  Unfortunately, I can’t find an email to that effect,
so I’ll ask that he confirm or deny that.

 

I've been thinking that
the client that is going to receive callbacks might want the reference
parameters that would be available if the service provider follows the rules
from the "Formulating a Reply Message" section of the WS-addressing
spec.

 

One way that a callback
could be distinguished from a reply is that the callback could have a
<relatesTo> header that uses a relationship type of
"oasis.org/isCallbackFor" and a reference to the messageID that the
callback is in response to.  I haven’t seen other uses of the
<relatesTo> header, but it seems like this is exactly the sort of thing
it is meant for.

 

Michael

 

 

From: Eric Johnson [mailto:] 

Sent: Monday, February 04, 2008
2:45 PM

To: Mike Edwards

Cc: OASIS Bindings

Subject: Re: [sca-bindings] ISSUE-22:
The Bindings specifications should provide exemplary Implementations for a)
Callbacks and b) Conversations

 

Logged as http://www.osoa.org/jira/browse/BINDINGS-22

-Eric.

Mike Edwards wrote: 

Raiser:                Mike
Edwards 

Target:
               Web Services Binding
specification, JMS Binding Specification, JCA Binding Specification

Description:

At
present, it is not clear which, if any, of the Bindings specifications enable the
implementation of two important 

features
of SCA described in the Assembly specification - namely Callback interfaces and
Conversational 

interfaces.

Each
of the Bindings specifications should explicitly declare if it is possible to
support each of these features. 

For
each of the Bindings specifications that claim to support either or both of
these features, the specification 

should
provide a full description of at least one exemplary implementation of the
feature using the Binding 

technology
described in the specification.  Multiple alternative implementations are
permitted and may be 

added
to the specification. 

For
example, it may be possible to implement Callbacks using WS-Addressing
capabilities with Web services. 

If so,
and example, showing the use of appropriate features of WS-Addressing and other
relevant WS-* 

capabilities
should be added to the specification.   If an alternative exists using
(say) WS-Context, then an 

example
based on that technology can also be provided. 

Proposal:

None
at present. 

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.

Co Chair OASIS SCA Assembly TC.

IBM
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