Section 14.9. Protocol State Machines


14.9. Protocol State Machines

Protocol state machines are a special kind of state machine focusing on how a protocol, such as a communication protocol (e.g., TCP), works. The main difference between protocol state machines and behavioral state machines, which we've focused on previously, is that protocol state machines don't show behavior along transitions or inside states. Instead, they focus on showing a legal sequence of events and resulting states. Protocol state machines are drawn in a tabbed rectangle with the name of the state machine in the tab followed by {protocol}, as shown in Figure 14-22.

Figure 14-22. Protocol state machine modeling the receiver side of a simplified communication protocol called My Communication Protocol (MCP)


Because protocol state machines don't show behavior, you can't model what the system is doing in responsefor example, if it's sending acknowledgements back. But it can be useful for showing how to work with an object or system, such as specifying a communication protocol or an expected call sequence for an object's operations.




Learning UML 2.0
Learning UML 2.0
ISBN: 0596009828
EAN: 2147483647
Year: 2007
Pages: 175

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