Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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# EJB Timer Service

The EJB Timer Service uses a database to store persistent information about EJB timers. The EJB Timer Service configuration can store persistent timer information in any database supported by the Application Server CMP container.

For a list of the JDBC drivers currently supported by the Application Server, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Release Notes. For configurations of supported and other drivers, see Configurations for Specific JDBC Drivers.

To change the database used by the EJB Timer Service, set the EJB Timer Service’s Timer DataSource setting to a valid JDBC resource. You must also create the timer database table. DDL files are located in install-dir`/lib/install/databases`. Ideally, each cluster should have its own timer table.

Using the EJB Timer Service is equivalent to interacting with a single JDBC resource manager. If an EJB component or application accesses a database either directly through JDBC or indirectly (for example, through an entity bean’s persistence mechanism), and also interacts with the EJB Timer Service, its data source must be configured with an XA JDBC driver.

You can change the following EJB Timer Service settings. You must restart the server for the changes to take effect.

- Minimum Delivery Interval - Specifies the minimum time in milliseconds before an expiration for a particular timer can occur. This guards against extremely small timer increments that can overload the server. The default is `7000`.

- Maximum Redeliveries - Specifies the maximum number of times the EJB timer service attempts to redeliver a timer expiration due for exception or rollback. The default is 1.

- Redelivery Interval - Specifies how long in milliseconds the EJB timer service waits after a failed `ejbTimeout` delivery before attempting a redelivery. The default is `5000`.

- Timer DataSource - Specifies the database used by the EJB Timer Service.

For information about configuring EJB Timer Service settings, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide. For information about the `asadmin list-timers` and `asadmin migrate-timers` commands, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual.

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