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e-docs > WebLogic Server > Programming WebLogic J2EE Connectors > Transaction Management |
Programming WebLogic J2EE Connectors
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The following sections describe the various types of transaction levels supported by the WebLogic J2EE Connector Architecture and explain how to specify the transaction levels in the resource adapter RAR archive.
Transactional access to EISes is an important requirement for business applications. The J2EE Connector Architecture supports the concept of transactions—a number of operations that must be committed together or not at all for the data to remain consistent and to maintain data integrity.
The BEA WebLogic Server J2EE Connector Architecture implementation utilizes WebLogic Server's robust Transaction Manager implementation and supports resource adapters having the following transaction support levels (as described in the J2EE Connector Specification, Version 1.0 Final Release):
Note: Refer to the following Sun Microsystems documentation for information on the ra.xml document type definition: http://java.sun.com/dtd/connector_1_0.dtd
For more information on supported transaction levels, see the "Transaction Management" chapter in the J2EE Connector Specification, Version 1.0 Final Release (http://java.sun.com/j2ee/download.html#connectorspec).
Specifying the Transaction Levels in the RAR Configuration
The resource adapter specifies which kind of transaction it supports in the ra.xml deployment descriptor file provided by Sun Microsystems. For instructions on specifying the transaction level type in the RAR, refer to Configuring the Transaction Level Type in Configuration.
Note: Refer to the following Sun Microsystems documentation for information on the ra.xml document type definition: http://java.sun.com/dtd/connector_1_0.dtd
Transaction Management Contract
In many cases, a transaction (termed local transaction) is limited in scope to a single EIS system, and the EIS resource manager itself manages such a transaction. While an XA transaction (or global transaction) can span multiple resource managers. This form of transaction requires transaction coordination by an external transaction manager, typically bundled with an application server. A transaction manager uses a two-phase commit protocol (2PC) to manage a transaction that spans multiple resource managers (EISes). It uses one-phase commit optimization if only one resource manager is participating in an XA transaction.
The J2EE Connector Architecture defines a transaction management contract between an application server and a resource adapter (and its underlying resource manager). The transaction management contract extends the connection management contract and provides support for management of both local and XA transactions. The transaction management contract has two parts, depending on the type of transaction.
These contracts enable an application server such as WebLogic Server to provide the infrastructure and runtime environment for transaction management. Application components rely on this transaction infrastructure to support the component-level transaction model.
Because EIS implementations are so varied, the transactional support must be very flexible. The J2EE Connector Architecture imposes no requirements on the EIS for transaction management. Depending on the implementation of transactions within the EIS, a resource adapter may provide:
WebLogic Server supports all three levels of transactions, ensuring its support of EISes at different transaction levels.
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