Transparent integration JBoss DNA as EIS into JEE app server environment .

The JCA specification is available here - http://jcp.org/en/jsr/detail?id=112

For instance, Apache JackRabbit has JCA connector -http://jackrabbit.apache.org/jackrabbit-jca-resource-adapter.html

It's not neccesary the core of the system but it adds an extra level of support for more convenient deployments and access to the JCR based system that we may not neccesary anticipate or expect up front.

http://java.sun.com/j2ee/connector/overview.html JEE Connector Architecture Overview
In short the J2EE Connector architecture defines a standard architecture for connecting the J2EE platform to heterogeneous EIS systems. Examples of EIS systems include ERP, mainframe transaction processing, database systems, and legacy applications not written in the Java programming language. By defining a a set of scalable, secure, and transactional mechanisms, the J2EE Connector architecture enables the integration of EISs with application servers and enterprise applications.

The J2EE Connector architecture enables an EIS vendor to provide a standard resource adapter for its EIS. The resource adapter plugs into an application server, providing connectivity between the EIS, the application server, and the enterprise application. If an application server vendor has extended its system to support the J2EE Connector architecture, it is assured of seamless connectivity to multiple EISs. An EIS vendor needs to provide just one standard resource adapter which has the capability to plug in to any application server that supports the J2EE Connector architecture.