OC4J Support for Connectors

The container plays an important part in the J2EE Connector Architecture by managing connection pools, transactions, security, and more. OC4J supports all of the features required by the JCA specification. However, it doesn't support two-phase commit, local transaction optimization, or connection sharing for J2EE Connectors. A J2EE Connector is much less scalable than a JDBC or message-based interface to your EIS; in some cases, it may even be better to use alternatives outside of the J2EE specification instead of Connectors. In some cases you have no other option because the Connector contains native code, but make sure you examine all the alternatives before assuming that a J2EE Connector is appropriate.

Before deploying to OC4J, all Connectors should be packaged in RAR files as described in the JCA specification. In addition to the standard ra.xml descriptor, an optional oc4j-ra.xml descriptor can be placed in the META-INF directory within the RAR to configure OC4J-specific settings or override ra.xml values. The format of oc4j-ra.xml is described later in this chapter.

Once configured and packaged, RARs can be deployed to OC4J as either standalone or embedded Connectors. Standalone Connectors are configured in the global Connectors file (usually "connectors/oc4j-connectors.xml" , but this can be changed through the "system.xml" configuration file). Connectors are available for use by all deployed applications. Embedded Connectors are packaged inside an enterprise archive (EAR) file and are only made available to the application inside which they're deployed. We'll cover the OC4J descriptor files in more detail later in the chapter.