Sun Microsystems' new Connector Architecture specification for the Java 2 platform, Enterprise Edition (J2EE) is important for everyone building Web applications using a J2EE application server. According to the results of a recent ebizQ poll, nearly two out of every three organizations are using an application server today. And most of these application servers--along with their associated Web applications--need to connect to one or more enterprise systems, be it an ERP application, a mainframe system, a database or some other enterprise application. That's where the J2EE Connector Architecture (JCA) comes in.

The JCA specification defines three key functions: The Common Client Interface (CCI), which provides a uniform client API across multiple enterprise information systems; The Service Provider Interface (SPI), which defines system-level contracts for connection management, transaction management and security between an application server and the adapter for a specific enterprise application; and a deployment and packaging protocol for the adapters.

The Benefits

The benefits of JCA are essentially fourfold:

1.   It complements JDBC and JMS.

Java Database Connectivity (JDBC) and Java Messaging Service (JMS) are well-known and widely used standard APIs for integration with enterprise systems. JDBC is used to access relational databases, and JMS comes into play when the enterprise system supports a message queuing interface. But what happens when the enterprise system does not support message queuing, and access at the database level is compromising data integrity? JCA solves this by allowing enterprise systems to be accessed via their native API.

2.   It harmonizes the way your application accesses external systems.

Have you ever imagined how helpful it would be if data in applications such as SAP, Siebel and CICS (IBM's Customer Information Control System) could all be accessed from your application in a single, uniform way? Well, that's what the CCI is about. It provides a generic, relatively low-level interface common across all JCA adapters. Of course, that doesn't mean JCA makes accessing data in diverse applications trivial; you still need to understand the applications to some extent to access them. The value of the CCI is that you don't need to study another API for each application and that, once you understand the mechanics, you can focus your efforts on the application content.