Re: Exchange type issue

In considering this, it is clear that we need the ability to distinguish whether an respond is associated with a particular request. However, there seems to be some difficulty with introducing a new action="notify" to do this. 

As such, would it be acceptible to everyone to instead use an additional attribute for action="respond"? I don't see that adding an attribute is semantically any different from adding a new action. However, it may be more amenable to those who would prefer not to express "in-out"/"notification" as a distinct action. 
 
If this direction is desired we could then have an attribute, notification="true", used/parsed only when action="respond", that would indicate that the response is not associated with a request. 

On Wednesday, November 01, 2006, at 09:09AM, "Gary Brown" <gary@pi4tech.com> wrote:
>
>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 Tuesday, 5 December 2006 04:56:57 UTC