Re: [ws-caf] Questions about section 3

["Mark Little" <mark.little@arjuna.com>]

I think this is an open-ended question that isn't just specific to
WS-Context. If you're using an unreliable delivery mechanism for aynchronous
"fire-and-forget" messages then there's no "guarantee" that those messages
will be delivered (I use the word in quotes because nothing's 100% anyway)
and hence responses won't come back. If you're using HTTP then you'll at
least get an ack back, but different bindings may behave differently.

RPC style does give you some benefits, because you're synchronously waiting
for a response. But even then it's implementation specific as to whether you
wait forever for a reply or just some timeout. Tying up two one-way requests
at the user level (using the WSDL currently defined in WS-Context, for
example) isn't that different, except perhaps you give the control over
waiting to the application rather than the communications infrastructure.
Retry mechanisms (if you think the message wasn't received) are also
implementation dependant.

But this definitely isn't specific to WS-Context and I haven't seen any
specs. that tackle it. Are there any?

As to what happens if you get an unsolicited message (e.g., a contentsSet
when no setContents was sent), then that's pretty much the same: it can
happen now, with A. N. Other specification. I suppose we could put something
in saying that such unsolicited responses are to be ignored, but is there a
standard disclaimer that others use?

Mark.

----
Mark Little,
Chief Architect, Transactions,
Arjuna Technologies Ltd.

www.arjuna.com

----- Original Message -----
From: "Murray, Bryan P." <bryan.murray@hp.com>
To: "Greg Pavlik" <greg.pavlik@oracle.com>
Cc: <ws-caf@lists.oasis-open.org>
Sent: Thursday, June 24, 2004 12:48 AM
Subject: RE: [ws-caf] Questions about section 3


> Section 5.2 is the other section containing message descriptions and it
> is fairly careful to indicate which follow-up messages can occur for any
> message received by the ContextService and which messages must contain a
> context header.
>
> There are aspects of what I mentioned for section 3 that can also be
> applied to section 5.2:
>
> - what should the user context service's behavior be if it receives a
> completed message without having sent a complete message?
>
> - is there a time the user context service should be expected to wait
> for a follow-up message? This is closely related to what is the expected
> behavior if a follow-up message is never received?
>
>
> Bryan
>
> -----Original Message-----
> From: Greg Pavlik [mailto:greg.pavlik@oracle.com]
> Sent: Wednesday, June 23, 2004 4:34 PM
> To: Murray, Bryan P.
> Cc: ws-caf@lists.oasis-open.org
> Subject: Re: [ws-caf] Questions about section 3
>
>
> is the latter part of this question generically applicable to all
> asynchronous callbacks in WS-Context?
>
> Murray, Bryan P. wrote:
>
> >In section 3 of WS-Context there are implications that messages are to
> >be generated by the ContextManager after it receives a message, but
> >there is no description about what specific messages are sent after
> >receiving the getContents and setContents messages.
> >
> >Figure 6 shows the possible interactions and seems to be the only
> >indication of the possible follow-up messages. After reading this
> >section it appears to be compliant for a ContextManager to send a
> >"contentsSet" message after receiving a "getContents" message. Is this
> >correct? What does this mean?
> >
> >What should be the behavior of the ContextRespondant if it receives a
> >contentsSet message without ever having sent either a getContents or
> >setContents message?
> >
> >How does the ContextManager know where to send follow-up messages?
> >There is a sentence in the introduction to section 3 talking about a
> >dereferencing call-back style, but I did not find text describing this
> >style in detail. There is a mention of call-back in section 1.2 and
> >section 1.3 talks about a referencing structure, but there is no clear
> >description of how all these parts come together to instruct the
> >ContextManager where to send follow-up messages.
> >
> >What should be the behavior of the ContextRespondant if it sends a
> >getContents message and never receives a follow-up message?
> >
> >What is the difference between the ContextRespondant and the
> >ContextResponseHandler?
> >
> >Is the ContextManager the same as the ContextService? I looked for a
> >glossary and did not find one. Section 1 does define some terms, but
> >ContextManager is not one of them.
> >
> >Which messages in section 3 must include a context SOAP header?
> >
> >Is there some length of time that a ContextRespondant should expect to
> >wait for follow-up messages? How is this defined?
> >
> >
> >Bryan
> >
> >
>
>