IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Services and service-related functions > Access external services with adapters > Configure and using adapters > IBM WebSphere Adapters > JDBC > Overview of IBM WebSphere Adapter for JDBC > Technical overview > Inbound processing

Standard event processing

In standard event processing, the adapter provides the SQL queries that poll for events and ensure that the event is delivered exactly one time.

Database triggers or tools such as Oracle Change Data Capture run when records are created, updated, or deleted in tables in the database. A trigger or other tool writes an event record into the event store, which is a persistent cache where event records are saved until a polling adapter can process them. The event store is implemented as a table in same database as the user tables, which are the tables that contain the database objects accessed by the adapter.

You must define the triggers or set up other tools to report changes to the database tables about which you want to receive events. The adapter provides a sample database script that shows how to set up triggers for the adapter. The samples are in the IID_installation_dir/ResourceAdapters/JDBC_ version/scripts directory, where version identifies the version of the adapter, for example, 7.0.0.0. A sample script is provided for IBM DB2 , IBM DB2 for z/OS , Oracle, and Microsoft SQL Server.

The adapter offers assured once delivery, which guarantees that each event is delivered once and only once to the export. If you enable assured once delivery for the module, a transaction ID (XID) is set for each event in the event store. After an event is obtained for processing, the XID value for that event is updated in the event store. The event is then delivered to its corresponding export, and then deleted from the event store.

If the database connection is broken or the application is stopped before the event can be delivered, the event cannot be processed completely. In this case, the XID column indicates that the event must be reprocessed and sent to the export again. After the database connection is re-established or the adapter starts again, the adapter checks for events in the event store that have a value in the XID column. The adapter processes these events first, and then polls the other events during the poll cycles.

The adapter can process all events or filter events by business object type. The filter is set by use of the activation specification property EventFilterType. This property has a comma-delimited list of business object types. Only the types specified in the property are processed. If no value is specified for the property, no filter is applied, and all the events are processed. If the activation specification property FilterFutureEvents is set to true, the adapter filters events by timestamp. The adapter compares the system time in each poll cycle to the timestamp on each event. If an event is set to occur in the future, it will not be processed until that time.

Inbound processing


Related concepts:

Custom event processing

Event store