- Declaring Events
- Accessing the Available State
- Accessing the Happened State
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- Causing an Event
- Implicitly Causing an Event
- Causing and Resetting an Event
- Partially Causing an Event
- Resetting an Event
- Waiting on an Event
- Waiting on Time
- Waiting on and Resetting an Event
- Waiting on Multiple Events
- Waiting for POSIX Signals
- Testing the Happened State
- Duration of the Happened State
- Using Implicitly Declared Events
- Using Interrupts
- Efficiency Considerations
- Discontinued Processes and Events
- Example of Event Usage
Events can be declared in ALGOL and COBOL programs, but not in other languages. Work Flow Language (WFL) jobs can wait on certain predeclared and implicitly declared events.
Events can be made available to tasks in the same way as other objects can. That is, internal tasks can access events declared globally in their parents. An internal or external task can be passed an event as a parameter.
An event consists of an identifier that has two states associated with it: the available state and the happened state. The available state can be AVAILABLE or NOT AVAILABLE. The happened state can be HAPPENED or NOT HAPPENED. These values can be inspected or changed by any of several event-related statements that are described in the following pages.
The available state of an event is typically used to temporarily restrict access to a particular object, so that only one process can access the object during a given period of time. The happened state is used to allow one or more processes to wait without using any processor time while waiting.
The initial available state of an event is AVAILABLE. The initial happened state of an event is NOT HAPPENED.
