Diagram to represent user interaction with different parts of the network

Question

Can anyone recommend a suitable diagram to represent user interaction with different physical systems as different tasks are performed?

I think something along the lines of a UML sequence diagram would be good, but I think they're more for OO programming than systems interaction..?

This is to represent a piece of non-OO PHP software that interacts with different cloud technologies to evaluate whether a certain concept could be feasible given the current state of technology. The software has already been built and the purpose of the diagram is for the accompanying research paper.

There are three key processes that test different areas of the same system, though they are all related. I'm not sure if one large or three smaller diagrams would be better.

Answer 1

If you want to emphasize what messages are being exchanged, then a sequence diagram is appropriate. While they are used for OO models, it is frequent to find them in network literature (e.g. this diagram).

If you want to emphasize the control flow, then you can use an activity diagram, or an interaction overview diagram (which is an activity diagram where the nodes describe interactions drawn as sequence fragments).