Event Requirements
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InterBase events are messages passed from a trigger or stored procedure to an application to announce the occurrence of specified conditions or actions, usually database changes such as insertions, modifications, or deletions of records.
Before an application can respond to an event, it must register interest in an event. To register interest in an event, the application must establish and populate two event parameter buffers (EPBs), one for holding the initial occurrence count values for each event of interest, and another for holding the changed occurrence count values. These buffers are passed as parameters to several API event functions, and are used to determine which events have occurred.
In C, each EPB is declared as a char pointer, as follows:
char *event_buffer, *result_buffer;
Once the buffers are declared, isc_event_block() is called to allocate space for them, and to populate them with starting values.
For more information about events, see Working with Events..