8.1 J2EE Connector Architecture Overview

The J2EE Connector Architecture specification, part of the overall J2EE specification, is intended as a standard mechanism for plugging heterogeneous Enterprise Information Systems into a J2EE-compliant Application Server. It allows J2EE applications to securely interact with non-J2EE applications in a transactional manner. Provided that there is a J2EE Connector Architecture resource adapter for the Enterprise Information System (EIS), the EIS and Application Server can collaborate on security, transaction, and connection management. A resource adapter is a standard, system-level software driver for the EIS.

The J2EE Connector Architecture specification (version 1.0) defines three system-level contracts:

Connection Management Contract: This allows the J2EE platform to pool connections to the EIS and allows applications to use those connections to interact with the EIS when needed.

Transaction Management Contract: This allows the J2EE platform to control interaction with the EIS transactionally .

Security Contract: This allows the J2EE platform to secure access to the EIS.

These contracts allow the Application Server to manage interaction with the EIS in a standard way. However, they are system-level contracts and as such are of concern only to those developing J2EE Connector Architecture resource adapters.

The latest version of the J2EE Connector Architecture specification (version 1.5) has added additional system-level contracts; however, these are of little relevance when using JDO within the J2EE environment at this time.

Figure 8-1 depicts how a resource adapter plugs into an Application Server and, through the J2EE Connector Architecture system-level contracts, manages the interaction between the Application Server and the EIS. As can be seen, the J2EE Connector Architecture resource adapter runs within the same JVM as the Application Server.

Figure 8-1. The J2EE Connector Architecture.

The J2EE Connector Architecture specification also defines a Common Client Interface (CCI). The CCI defines standard APIs for J2EE applications to connect and interact with an EIS in a standardized, record-oriented manner.