A Java Database Connectivity (JDBC) data source is an object bound to the Java Naming and Directory Interface (JNDI) tree that includes a pool of JDBC connections. Applications can look up a data source in the JNDI tree and then reserve a database connection from the data source. You create queues in which to enqueue outgoing messages or dequeue incoming messages. The Oracle JCA adapters listed in Table 48-1 require JDBC data sources and queues to be configured before deployment.