Connectivity 

To connect to the Java persistence layer in the J2EE Engine, you use an instance of javax.sql.DataSource. You need a DataSource for both relational and object-oriented persistence, since the underlying datastore in both cases is a relational database.

At installation the system creates a default DataSource, which you can use in your applications as well. Typically, you do that by deploying an alias for it. For more information, see Using the Default DataSource and Registering a DataSource Alias.

You can also create a new DataSource either using the Visual Administrator or by adding a relevant XML file to an application or library archive. For more information, see Creating a DataSource.

In addition, this section provides information about how to reconnect to a database if it crashes.