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The application level contract defines the API used by a client to access a

resource adapter for an EIS. This API may be the Common Client Interface (CCI),

which is a generic API for accessing multiple heterogeneous EISs, or it may be a

resource adapter specific API. 

The initial release of the Connector architecture, which is part of the J2EE 1.3

platform, established three system level contracts, as follows: 

  Connection management contract Supports connection pooling to an under 

lying EIS, an important requirement for scalable applications.

  Transaction management contract Supports local and global transactions, 

and enables management of (global) transactions across multiple EISs. 

  Security management contract Enables secure interchanges between an EIS 

and a J2EE application server and protects EIS managed resources.

The most recent release (version 1.5) of the Connector architecture expanded

the capabilities of resource adapters. This release expanded the transaction

support for a resource adapter. Previously, a transaction had to start from an enter 

prise bean on the J2EE application server, and it remained in force during opera 

tions on the EIS. Now, transactions can start on the EIS and be imported to the

application server. The J2EE Connector architecture specifies how to propagate

the transaction context from the EIS to the application server. The Connector

architecture also specifies the container's role in completing a transaction and

how it should handle data recovery after a crash.

The current version also specifies additional system level contracts to the

initial three contracts just noted. These new contracts are:

  Messaging  pluggability  contract Extends the capabilities of message 

driven beans so that they can handle messages from any message provider rath 

er than being limited to handling only JMS messages. By following the APIs 

for message handling and delivery specified in this contract, an EIS or message 

provider can plug its own custom or proprietary message provider into a J2EE 

container. JAXM is a good example of this type of message provider.

  Work management contract Enables the J2EE application server to manage 

threads for resource adapter, ensuring that resource adapters use threads prop 

erly. When a resource adapter improperly uses threads, such as when it creates 

too many threads or fails to release threads, it can cause problems for the entire 

application server environment. Poor thread handling by a resource adapter can