The Java EE Connector Architecture defines system contracts between a Java EE server and an EIS that enable inbound connectivity from the EIS: pluggability contracts for message providers and contracts for importing transactions.
To enable external systems to connect to a Java EE application server, the Connector Architecture extends the capabilities of message-driven beans to handle messages from any message provider. That is, message-driven beans are no longer limited to handling JMS messages. Instead, EISs and message providers can plug any message provider, including their own custom or proprietary message providers, into a Java EE server.
To provide this feature, a message provider or an EIS resource adapter implements the messaging contract, which details APIs for message handling and message delivery. A conforming resource adapter is assured of the ability to send messages from any provider to a message-driven bean, and it also can be plugged into a Java EE server in a standard manner.
The Connector Architecture supports importing transactions from an EIS to a Java EE server. The architecture specifies how to propagate the transaction context from the EIS. For example, a transaction can be started by the EIS, such as the Customer Information Control System (CICS). Within the same CICS transaction, a connection can be made through a resource adapter to an enterprise bean on the application server. The enterprise bean does its work under the CICS transaction context and commits within that transaction context.
The Connector Architecture also specifies how the container participates in transaction completion and how it handles crash recovery to ensure that data integrity is not lost.