What Does an iIS Process Engine Do?
What Does an iIS Process Engine Do?
As suggested in “What Is an iIS Process Engine?” on page 27, an iIS process engine performs a number of different functions in support of an iIS system. These include the following.
Managing sessions The engine opens, suspends, and closes sessions. When opening a session, the engine first validates a user’s logon against an organizational database. For more information on sessions, see “Engine Sessions” on page 158.
Executing processes The engine creates instances of a process and manages their execution from start to finish. During each process’ execution, a succession of activities is performed by applications that have opened sessions with the engine. The engine manages and tracks these activities through to their final completion.
Registering distributions Process definitions, assignment rule dictionaries, user profiles, and a validation constitute the process logic components executed by the engine during process execution. Registration lets you change these components dynamically as business processes and organizational structures change.
Maintaining an engine history database The engine can maintain a history of each process execution, writing all changes of state to an engine history database. The history can include changes of state in activities, process attributes, timers, and so on.
While process execution is the key engine function, managing sessions, registering definitions, and maintaining the history database are all necessary to support process execution.
To provide these functions, the iIS engine is internally structured around a number of manager objects, as shown in Figure
•Session
•Process
•Registration
•History
