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FDC_START_TIMERDAEMON - Delete locks and sessions created by OData posting applications in FI

Purpose

The standard SAP locking mechanism uses the enqueue server. The lifetime of an enqueue lock is bound to the ABAP user session in which it was created – with other words: the ABAP user session is the “owner” of the lock. If an ABAP user session ends, all locks owned by this ABAP user session will be deleted.

The Fiori applications use OData services for backend communication. For each OData HTTP request a new ABAP user session is created and terminated directly after the response is serialized, or if an error has occurred. This means, that at the end of each request all enqueue locks are gone. As of today it is not possible to set an enqueue lock which survives the end of a standard OData HTTP call.

Therefore locks are stored in a database table and outdated locks must be deleted periodically by a background process.

Activities

Define a background job for event SAP_SYSTEM_START starting report FDC_START_TIMERDAEMON. No parameter and variant are required.

The report will start a background process (daemon ) as an asynchronous RFC - visible in SM04 with title "FDC: Timer Daemon" in transaction SM04. Every 5 minutes the daemon will clean up sessions, that were not updated the last 120 minutes.

Additionally schedule the background job e.g. every hour, to check, that the daemon is still running. An enqueue on table FDC_TIMERDAEMON_LOCK ensures, that there is only one daemon running. This lock is visible in SM12.

For releases > S4CORE 102 and > SAPSCORE 110 the report FDC_START_TIMERDAEMON also cleans up held documents saved from Post General Journal Entries older than 180 days for data privacy reasons. You can change the retention period by setting a parameter 'Retention for held documents' when scheduling the report.