Follow up on output ops + MEPs

Summarizing yesterday's discussions, it seems to me that there was some 
interest for the following definition of an operation:
    - an operation is defined by a MEP and a role
    - a server can only take role values that are defined by the MEP.
example:
     - operation Foo1 is Request/Response and the service role is : 
RespondingNode
            => this is the well-known input/output operation
     - operation Foo2 is Request/Response and the service role is : 
RequestingNode
            => this is one interpretation (amongst several) of the 
output/input operation
RequestingNode and RespondingNode are roles that must be defined in the 
Request/Response MEP.

This allows clarifying the semantics of all operations. If somebody has 
used the output/input operation in a different way, he/she should build 
another mep with well-defined semantics.
            => less (no more ?) confusion with operations semantics
With this definition, we would have two meps in our current WSDL, 
request/response and one/way, each one defining two roles...

Following Don's proposal [1], the changes to be made would be quite 
small, something more or less like:
<operation name="GetResponse"
                mep="http://www.w3.org/mep/request-response"
                myRole="req-resp:RespondingNode"
                xmlns:req-resp="http://www.w3.org/mep/request-response">
...
</operation>
I think that Kevin's use cases [2] can be handled by this simple addition.

In any case, this is an interesting addition to Don's proposal imho: as 
pointed out by Jacek [3], MEPs might deal with multiple nodes 
interactions while WSDL only deals with the service's point of view. The 
role info might partially solve this issue.

Following on example 2 (event notification) of Don's proposal (for 
illustration purposes only):
<operation name="Event-In"
        mep="http://www.example.org/mep/event-notification/"
        myRole="event:notifier"
        xmlns:event="http://www.example.org/mep/event-notification/">
...
</operation>
<operation name="Event-Out"
        mep="http://www.example.org/mep/event-notification/"
        myRole="event:subscriber"
        xmlns:event="http://www.example.org/mep/event-notification/">
...
</operation>


Comments,
   Youenn
[1] http://lists.w3.org/Archives/Public/www-ws-desc/2002Nov/0085.html
[2] http://lists.w3.org/Archives/Public/www-ws-desc/2002Dec/0054.html
[3] http://lists.w3.org/Archives/Public/www-ws-desc/2002Nov/0090.html