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This article discusses the types of message flows in synchronous and asynchronous communication, including nested flow of control, interruption prevention, callbacks, and deletion of objects.
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types of message flows • synchronous • indicates nested flow of control • used to ensure that state cannot be compromised by • external factors e.g. not interrupted by the operating system • invoking object halts execution while it waits for a return • completion • invoked object finishes • asynchronous • signal from one object to another • invoking object does not halt execution while it waits a return • callback • notification of completion from invoked object
print shop branching and asynchronous messages and deletion of objects
(R, S) use case “place a telephone call” this diagram could be extended to show the two parties disconnecting
Fig. 12.24 UML and the Unified Process: Practical Object-Oriented Analysis and Design. Arlow & Neustadt. Addison-Wesley. 2002
showing active
multi- threading