JDBC Services

Java EE applications access the database through JDBC data sources that abstract the database integration and connection management for them. A WebLogic Server JDBC data source encapsulates a JDBC driver, a set of connection information—pointing to a specific schema within an RDBMS of the type matching the data source’s driver—and a pool of active connections to the schema that is referred to by the connection information. Figure 2-2 illustrates the main elements of a WebLogic JDBC data source.

Upon startup, each WebLogic Server instance initiates its configured data sources with a certain number of active connections. Data sources are accessed by clients through a JNDI lookup, and the availability of the data source to a client’s scope is determined by its server targeting. In other words, a data source’s JNDI name is only available to the WebLogic server instances to which the data source is assigned at creation time. As clients access a data source, it provides them with an active connection from its pool for their use. If the pool runs out of connections, the data source can expand its connection pool size until it reaches a maximum count. The initial, maximum, and incremental size increases of a data source are all configura....