W3C home > Mailing lists > Public > public-ws-chor@w3.org > November 2006

RE: Exchange type issue

From: Martin Chapman <martin.chapman@oracle.com>
Date: Fri, 3 Nov 2006 14:32:24 -0000
To: "'Gary Brown'" <gary@pi4tech.com>, "'WS-Choreography List'" <public-ws-chor@w3.org>
Message-ID: <011f01c6ff54$e1cbbf80$8540908d@ie.oracle.com>

In 1), why would we ever allow a response that has not had a preceeding request? This should be illegal! The only chellange is being
able to match a response with a request. We could also allow fancy patterns such as one request and mutiple responses (of same or
different type) without introducing this "notify" flag.

Martin.

>-----Original Message-----
>From: public-ws-chor-request@w3.org 
>[mailto:public-ws-chor-request@w3.org] On Behalf Of Gary Brown
>Sent: Wednesday, November 01, 2006 9:06 AM
>To: 'WS-Choreography List'
>Subject: Exchange type issue
>
>
>
>Hi
>
>As discussed on the conf call last night, I will outline the 
>requirements for this change and the benefits if can offer.
>
>1) We need the ability to distinguish whether or not an exchange with 
>action="respond" is coupled with a preceding exchange with 
>action="request".
>
>A simple scenario would be where an interaction, with a request 
>exchange, is followed by a choice that has two paths, and each 
>path has 
>an interaction with a 'respond' exchange for a normal response. 
>Currently it is not possible to determine whether one of these is 
>intended to be a response coupled with the request, or whether 
>both are 
>'out only' messages, or whether the user has in fact made an error in 
>the choreography design, and is expecting both to be responses to the 
>request.
>
>2) The benefits of having a clear and explicit understanding 
>of whether 
>a response is actually coupled to a preceding request are:
>
>a) Static validation - we can determine when a user has made an error, 
>by specifying two normal responses.
>
>b) Deriving correct service interfaces - service interfaces can be 
>derived from the choreography description. However at the 
>moment, even a 
>simple case where there is a request followed by a separate 
>interaction 
>including a respond exchange, it may be unclear whether they are a 
>one-way request followed by an 'out-only', or whether they are a 
>request-response pair. Making this explicit in the choreography means 
>that these ambiguities would not arise.
>
>
>In relation to the terminology question, after further thought 
>I believe 
>that 'notify' is actually a suitable value for the new exchange action 
>type. This is because it is exactly that, an action. The term notify 
>simply means that someone will be informed, it does not imply whether 
>there is one or more parties being informed. This is determined by the 
>communication structure on which that notification is being sent - and 
>at present CDL only supports point to point.
>
>Regards
>Gary
>
>
>
>
Received on Friday, 3 November 2006 14:31:41 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 18 December 2010 01:01:47 GMT