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UML IN A PRODUCTýS LIFE CYCLE

by Venu Kosuri

Start ý Basic Views ý The Whole Picture ý Use Case View ý Use Case Diagram ý Structural View ý Domain Modeling ý Class Diagram ý Behavioral View ý Sequence Diagram ý Collaboration Diagram ý FSM ý Scalability Limitations ý Lack of Support ý State Charts ý Activity Diagram ý Implementation View ý Environmental View ý Sources and PDF

LACK OF SUPPORT

Another serious problem with the traditional state machine is its lack of support for concurrency. This leads to a combinatorial explosion in the number of states to model. Consider a simple system that can be thought of as in one of four statesýoff, start-up, operational, or error. Also, it can run from either battery or main.

The fact that the system is in operational state is totally independent of whether or not it is running from battery or main. However, because traditional FSMs have no notion of independence, you must combine the independent states together. This yields a state like operational-battery and operational-main.

If you could model the FSM as two independent parts, the diagram would be simplified. This is called the combinatorial state explosion because the modeling of multiple concurrent FSMs requires the multiplication of the number of states in each to model all conditions. This requires O(xn) states to model N state machines with an average of X states in each. Logically, it should be possible to model such a concurrent system in O(xn) states, a much simpler proposition.

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