I am working on a project with multiple executables. They communicate by sending messages between one another. The messages are simple data structures (typedef'd C structs, to be specific) passed over network sockets. We have our own library that handles sending and receiving the messages.

Previously, we have used sequence diagrams to show how the messages flowed through the system for things like initialization, shutdown, and other major functional threads. Each flow on the sequence diagram was labeled with the message name.

Now we are moving toward using Rhapsody and modeling the whole system, rather than just the sequences. We have the messages created as classes. However, the flows in Rhapsody's sequence diagrams (and the UML standard) are essentially function calls, rather than structure names. We do not currently have a separate function for each flow. Thus, I am struggling with how to show the relation of the flows in the sequence diagram and the messages that they represent.

We are currently putting in Event flows (since operation is asynchronous) with the name of the message. However, this means there is no relationship in the model between the flow and the message structure. Has anyone done modeling of systems like this before? If so, I would be interested to know how you showed these types of message flow sequences.

Thanks.

Isn't there a method/function call that sends the struct/'Message' (maybe as an argument) through a socket?

It's a good question. At least it's a question that a lot of us have grappled with over recent years as 'systems' has met 'software' in modelling.

I have attached a little model that might help. It's the essence of what I do.