Re: MEP and Operations

Jeffrey Schlimmer wrote:

>FABLET Youenn [mailto:fablet@crf.canon.fr] wrote:
>
>>Let's have an operation that takes as input a date and a country name. 
>>As output, you get the size of the population of this country at that
>>
>date.
>
>>IMO, the definition of this operation  should not change whether:
>>   - you receive the date and country name as one message or two 
>>separate messages
>>   - you send the output to the requester A, to another node B or both
>>
>
>>A and B.
>>
>
>Of course _something_ must be different. The question is whether one
>needs another degree of abstraction beyond the port type/operation. Do
>you have a use case in mind where an operation is split into multiple
>messages in one case but kept as a single message in another?
>
>--Jeff
>
Here are two use cases that are relevant IMO.

First example :
    A wants to receive the score of the US vs Germany soccer match.
    1) A sends a message and receives the score once => one message
    2) A sends a message and A receives the score every 5 minutes => 
multiple messages

    In this example, the operation at the portType level should be 
defined the same way and/because the operation definition should not 
preclude one particular mep implementation.
    The binding info is of course not the the same in case 1) and 2)

    You can also implement the same operation but with a different mep: 
request/response+ forward (the same output message is sent twice to 
different recipients). The necessary mep information to provide (in this 
case the second recipiend adress) should not appear at the 
operation/portType level but at a mep/binding level.

Second example:
Let's have A a client, B a bank and C a vendor.
A wants to make a purchase order and for that purpose, A wants B to give 
to C a 10$ certificate.
Option 1:
    A sends its purchase order to B.
    B adds a 10$ certificate in the message.
    B sends the whole message to C => one message with two parts
Option 2:
    A sends a message to B to request a 10$ certificate for C.
    A sends through a prior SSL connection the purchase order directly 
to C. (A does not want B to receive the purchase order. Of course you 
can encrypt it but it becomes quickly complex).
    B sends a 10 $ certificate to C.  => 2 messages with one part.
    (Though an alternative (and better ?) way could be: A receives the 
10$ certificate from B and sends the whole message to C. C might 
nevertheless require that all certificates come directly from B1, B2 or B3).


    Youenn