Need some clarification on actions, message exchange, & operations

Frank and Team,

 

We need to resolve some of the ambiguities 
surrounding the following concepts and their relationships in the context of 
service interaction:

 

1. Actions

2. Action model

3. Operations

4. Message exchange

5. Real world effect

6. Execution context

 

Omitting item 6 for the moment, here's what I've 
captured during my note taking from the various telecons and discussion 
threads.

 

* An action is expressed or defined in terms of 
message exchange between participants. In other words, exchange of a message 
counts as performing an action.

* The action 
model (an element of a service description’s behavior model) describes 
the set of actions required to result in a real world effect.  

* The combination of the message exchange and the 
message content denote the action. 

* The action results in an operation being performed. 

* The result of an action can result in an operation 
on the service and the result of an operation would be the real world effect. 
  Consequently, the action 
results in an operation being performed

So, one concept that needs to be clarified based on the 
attached UML diagram is operation (see fourth bullet above).  In other 
words, does operation exist in between action and real world result?  And 
what about the content of the message as stated in the third bullet 
above.

Obviously, there are some ambiguities here and I'd 
appreciate any help in the clarification so we can press ahead with the 
write-up.  In the meantime, I will describe and model a few common MEPs and 
include them in the write-up as well as the common interaction model that 
depicts the role of the service participants, agents, and intermediaries (PEP, 
PDP).

Cheers...

 - Jeff E.

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