Java Connector Architecture

The J2EE Connector Architecture (JCA) provides a standard method of integrating enterprise information systems (EISs) and resources with J2EE applications. JCA connectors (also called resource adapters) are EIS-specific components that let you access ERP applications (such as SAP R3), legacy systems, and databases. The resource adapter, which is typically supplied by the EIS vendor, provides services and interfaces that let it integrate with the server (for things such as security and transactions) and with client applications.

Similar to the way that enterprise applications are packaged in an EAR file, resource adapters are packaged in resource archive (RAR) files, which include a deployment descriptor (in the META-INF/ra.xml file) and a JRun-specific deployment descriptor (in the META-INF/jrun-ra.xml file). You deploy JCA connector RAR files in the same manner as enterprise applications, web applications, and EJBs.

At runtime, JRun stores the resource adapter in JNDI (as specified in the jndi-name element of the jrun-ra.xml file) and client applications access it through an InitialContext.lookup method. As with InitialContext.lookups for JDBC, JMS, and JavaMail, a factory is returned that allows client access to an EIS-specific API. A resource adapter can optionally offer client access to the EIS through the common client interface (CCI), which provides a standardized API for client access to vendor-specific functionality.

One use for a connector is as a JDBC data source. The connector contained in the sample blackbox-notx.rar file illustrates this functionality.

To use the blackbox-notx.rar connector:

Uncompress the RAR file into a directory structure. This directory includes the blackbox-notx.jar file and deployment descriptors in the META-INF directory.
Modify the connectionURL property in the META-INF/jrun-ra.xml file. Set the value to the URL for an existing data source.
This overrides the corresponding property in the ra.xml file. For example, if you are running the PointBase sample database, you might specify jdbc:pointbase:server://127.0.0.1:9192/sample, as the following code shows:
```
...
<config-property>
   <config-property-name>ConnectionURL</config-property-name>
   <config-property-type>java.lang.String</config-property-type>
   <config-property-value>jdbc:pointbase:server://127.0.0.1:9192/sample</config-property-value>
</config-property>
...
```
Use the jar utility to compress the files back into a RAR file.
Deploy the RAR file in JRun. You can copy the file to your server root directory (if you enabled auto-deploy) or use the JMC.
Access the data source as you would any other JDBC data source. Use the value specified in the jrun-ra.xml file's jndi-name element when calling the InitialContext.lookup method.

The JRun samples server includes this RAR file and you can use it to access the samples database.

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