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 > Flat Files > Overview of WebSphere Adapter for Flat Files > Technical overview > Inbound processing
Event store
The event store is a persistent cache where event records are saved until the polling adapter can process them. The adapter uses event stores to track inbound events in the system. Each time a file is created, updated, or deleted, the adapter updates the status of the event in an event store. The status of each event is continuously updated by the adapter for recovery purposes until the events are delivered to the export.
If the adapter detects that there is no event store for the inbound module in the local file system, it automatically creates one when the application is deployed to the runtime environment. Each event store created by the adapter is associated with a specific inbound module. The adapter does not support multiple adapter modules pointing to the same event store.
When the adapter polls the local file system, it creates an entry in the event store for each event that matches the search criteria specified in the activation specification properties. The adapter records the status of each new entry as NEW.
If an event is successfully posted, event store entries are deleted. For failed events, the entries remain in the event store. Optionally, the adapter can archive successfully polled event files in an archive directory. The adapter supports processing of event files without any restriction on the file size.
Failed events can result from incorrect data in the event file.
For example, a field named fname might appear as fnam. The only way to correct the situation is to send the event file again with the correct data.
The adapter provides assured-once event delivery. This means that each event is delivered once and only once.
If you set the AssuredOnceDelivery activation specification property to True, the adapter stores an XID (transaction ID) value for each event in the event store. When an event is obtained for processing:
- The XID value for the event is updated in the event store.
- The event is delivered to its corresponding export.
- The event is deleted from the event store.
The following figure illustrates the event management flow for the adapter.
Figure 1. Event management flow
- Event store structure
The event store is used by the adapter to track events. - Event archival values
You can configure the adapter to archive processed event files in a directory, which you can then access to obtain a list of processed events. The file extension reflects whether an archived event was successful or not.