Re: [ws-rx] Minimalist GetMessage proposal: the anon use case

[Paul Fremantle <paul@wso2.com>]

Jacques

You are quite right. This is an interesting situation. One of the 
problems is that we do not in this spec define how messages are 
allocated to sequences. The IBM proposal simply shifts this problem to 
the EPRId as you point out.

In one of my own early drafts of the proposal I had these words in 
section 4.2, but I removed them for simplicity. However, if they are 
useful they could be added back.

"The WSRM specification does not define the allocation of messages to a 
sequence. In the case of reliable request-response with an anonymous 
client, the server MAY make a correlation between an incoming sequence 
and an offered sequence. In the case where the request message is 
unreliable, and the client is anonymous, there might not be a clear 
basis to allocate messages to a given sequence. In this scenario the 
client MAY add the <wsrm:Identifier> of the offered sequence as a SOAP 
Header element or elsewhere in the message as a hint to the server."

Paul

Durand, Jacques R. wrote:
> Paul:
>
> Are you sure this works when two different (un-addressable) clients are
> sending an anonymous wsrm:Offer/wsrm:Endpoint to the same RMS-to-be
> endpoint, say for offering sequences S1 and S2? 
> The offered sequences S1 and S2 have to be clearly associated from the
> start with the right client-RMD, by the server-RMS.
> With an in/out pattern where the in message is not sent reliably, how
> would the server-RMS know if it should use S1 or S2 when sending the out
> message for an in  message of one of the two initiators?
> Don't we still face the same issue of distinguishing anonymous endpoints
> that IBM proposal tries to address ( with wsrm:EPRid) ?
> (Do I miss something?)
>
> Jacques
>
> -----Original Message-----
> From: Paul Fremantle [mailto:paul@wso2.com] 
> Sent: Wednesday, May 03, 2006 12:05 PM
> To: wsrx
> Subject: [ws-rx] Minimalist GetMessage proposal
>
> Based on some of the discussions it seemed to me that it could be 
> valuable to produce a completely "minimalist" GetMessage proposal.
>
> This is a new proposal that is based on the previous WSO2 proposal.
>
> The proposal removes the MessageID selector in the GetMessage - relying 
> on simply getting whatever message the server sends back next.
>
> Also it removes the section 4.2. Effectively section 4.2 is an 
> optimisation: for example to support unreliable-in/reliable-out a client
>
> could do a createsequence+offer and never use the outgoing sequence. In 
> this case there is an overhead, which 4.2 aimed to remove, but this 
> simplifies the proposal by focussing on the bare minimum required to 
> support the most common use cases, but still allowing the other use case
>
> with a slight overhead.
>
> I've also included a sample message flow which I hope helps understand 
> the proposal and show the general usage.
>
> Paul
>
>   

-- 

Paul Fremantle
VP/Technology, WSO2 and OASIS WS-RX TC Co-chair

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"Oxygenating the Web Service Platform", www.wso2.com