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Chapter 8 State DiagramsChapter 9 Activity DiagramsChapter 10 Deployment DiagramsUML DistilledMartin FowlerChapter 8 State DiagramsThe full name should be state transition diagrams, which defines a number of states and describe the transitions between the states.TerminologyActions are associated with transitions and are considered to be processes that occur quickly and are not interruptible.Activities are associated with states and can take longer. An activity can be interrupted by some event.A guard is a logical condition that will return only “true’ or “false”.A big disadvantage for state transition diagrams is that they mean you have to define all the possible states of a system. So for large systems there is an exponential growth in the number of states. A better way is to defineseparate state-transition diagrams for each class. The most popular state transition diagram is Harel Statechart.When to use State DiagramsState diagrams are good at describing the behavior of an object across several use cases. They are not very good at describing behavior that involves a number of objects collaborating together.Chapter 9 Activity DiagramsThe activity diagram describes the sequencing of activities, with support for both conditional and parallel behavior. An activity diagram is a variant of state diagram where the states are activity states.TerminologyA branch has a single incoming transitions and several guarded outgoing transitions.A merge has multiple input transitions and a single output. It marks the end of conditional behavior started by a branch.A fork has one incoming transition and several outgoing transitions.Activity diagrams merely states the essential sequencing rules you have to follow, it can handle parallel processes by fork and join. Forks and joins must match to synchronize.Decomposing an ActivityA subsidiary diagram may have multiple exit points. One exit state is default, and the others are stub states.When to use Activity diagramsActivity diagrams are really nothing more than an UML-complaint flow chat, which is not object-oriented. Use activity diagrams in the following situations.- Analyzing a use case- Understanding workflow- Describing a complicated sequential algorithm- Dealing with multi-threaded applicationsDon’t use it in the following situations.- Trying to see how objects collaborate- Trying to see how many object behaves over its lifetimeChapter 10 Deployment DiagramsA Deployment Diagrams shows physical layout of components on hardware nodes. A deployment diagram is a good place to show how components and objects are routed and move around a distributed system.When to use deployment diagramsDistributed


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