Jakarta Connectors

Jakarta Connectors (JCA; formerly Java EE Connector Architecture and J2EE Connector Architecture) is a Java-based tool for connecting application servers and enterprise information systems (EIS) as part of enterprise application integration (EAI) solutions. While JDBC is specifically used to connect Java applications to databases, JCA is a more generic architecture for connection to legacy systems. JCA was developed under the Java Community Process as JSR 16 (JCA 1.0), JSR 112 (JCA 1.5) and JSR 322 (JCA 1.6).
JCA and Java EE.
J2EE Version 1.3 requires application servers to support JCA Version 1.0. J2EE Version 1.4 requires application servers to support JCA Version 1.5.
Java EE Version 6 requires application servers to support JCA version 1.6.
Contracts.
The Jakarta Connector Architecture defines a standard for connecting a compliant application server to an EIS. It defines a standard set of system-level contracts between the Jakarta EE application server and a resource adapter. The system contracts defined by Version 1.0 of the J2EE Connector Architecture are described by the specification as follows:
JCA Version 1.5 adds system contracts to the specification as follows:
EIS Integration.
JCA adapters can be built to integrate with various Enterprise Information System such as Siebel Systems, SAP AG, Great Plains Systems, Oracle Applications, etc. Siebel provides API to integrate with various platforms like Java, C++, .NET, Visual Basic, etc. For Java it provides an interface called 'Java Data Bean' (JDB). The Siebel adapter provides data access via the JDB API. Great Plains Systems provides an interface called eConnect to integrate with other platforms. SAP provides an interface for Java called SAP Java Connector (SAP JCo).