How to model communication protocol?

[jakson]

I've modeled data frames (header, messages, structures) that will be sent and received through ethernet.
Now I want to model communication protocol (what frame(s) is expected after another, ACK, NACK, timeouts, etc.).

It there any tutorial on how to model such (simple) communication protocol in EA?

[qwerty]

You could using Timing diagrams for that. To show logical order/conditions use a State diagram.

q.

[Colin Coates]

One way of modelling a protocol would be:

• Create a class diagram.
• Add an Interface to the diagram.
• Add methods to the interface to describe the operational contract of the protocol (such sendHeader, sendMessage, and so on).
• Add a state machine to Interface element (right-click the interface in the diagram, and add child diagram) to model its behavior (especially in terms of ordering and timeouts).

Ideally, you would use a UML2 protocol state machine to do this, but Sparx Enteprise Architect does not currently support the correct syntax for transitions (so no way to do "[precondition] trigger [postcondition]" so far as I can see). Realistically, you can probably get by with standard behavioral state machines, which will be fine for describing triggers, guard conditions and timeouts... It would be nice to see proper support for protocol state machine syntax, though!