Waiting for Events with EVENT WAIT
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Even after an application registers interest in an event, it does not receive notification about that event. Before it can receive notification, it must use the
EVENT WAIT statement to indicate its readiness to the event manager, and to suspend its processing until notification occurs.
To signal the event manager and suspend an application’s processing, use the following
EVENT WAIT statement syntax:
EXEC SQL EVENT WAIT request_name;
<request_name> must be the name of a request handle declared in a previous
EVENT INIT statement.
The following statements register interest in an event, and wait for event notification:
EXEC SQL EVENT INIT RESPOND_NEW ('new_order'); EXEC SQL EVENT WAIT RESPOND_NEW;
EVENT WAIT is executed, application processing stops until the event manager sends a notification message to the application.
- Note: An application can contain more than one
EVENT WAITstatement, but all processing stops when the first statement is encountered. Each time processing restarts, it stops when it encounters the next
If one event occurs while an application is processing another, the event manager sends notification the next time the application returns to a wait state.