Hierarchical Cascading of State/Event Machines
Original Publication Date: 2003-Nov-25
Included in the Prior Art Database: 2003-Nov-25
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In every communication session, session related data needs to be controlled and maintained. If one of the communication partners requires supplementary internal session data, and if this internal data is again related to the global session data, then complex relations arise, which become more and more difficult to handle as communication partners are added or removed. Often session related data is stored on different places in parallel. Sometimes very chaotic and thus error sensitive constructions occur, or else, restrictions are defined in order to prevent too complex data linkages to built up. Therefore, a generic way of establishing session related data is needed. To avoid these problems, a method for cascading State/Event Machines (SEMs) is described below. A State/Event Machine Controller instantiates a task and its assigned SEM. Depending on the kind of application, it can be necessary to instantiate further, subordinate SEMs, which maintain and process their own session related data. No data is stored double, though changes in one SEM can cause changes of data in another. This is initiated by internal events sent to the Event Distributor (ED), which is distributing any message, internal or external, to the appropriate SEM.