About the Transaction Service
WebLogic Server provides a Transaction Service that supports transactions in EJB and RMI applications.
In the WebLogic Server EJB container, the Transaction Service provides an implementation of the transaction services described in the Enterprise JavaBeans Specification 3.0 at
For EJB and RMI applications, WebLogic Server also provides the
javax.transaction.xa packages, which implement the Java Transaction API (JTA) for Java applications. For more information about JTA, see the Java Transaction API (JTA) Specification 1.1, published at
http://www.oracle.com/technetwork/java/javaee/jta/index.html. For more information about the
UserTransaction object that applications use to demarcate transaction boundaries, see
weblogic.transaction.UserTransaction in the Java API Reference for Oracle WebLogic Server.
Capabilities and Limitations
Learn about the capabilities and limitations of the Transaction Service that supports EJB and RMI applications.
Lightweight Clients with Delegated Commit
A lightweight client runs on a single-user, unmanaged desktop system that has irregular availability. Owners may turn their desktop systems off when they are not in use. These single-user, unmanaged desktop systems should not be required to perform network functions such as transaction coordination. In particular, unmanaged systems should not be responsible for ensuring atomicity, consistency, isolation, and durability (ACID) properties across failures for transactions involving server resources. WebLogic Server remote clients are lightweight clients.
The Transaction Service allows lightweight clients to do a delegated commit, which means that the Transaction Service allows lightweight clients to begin and terminate transactions while the responsibility for transaction coordination is delegated to a transaction manager running on a server machine. Client applications do not require a local transaction server. The remote implementation of
UserTransaction that EJB or RMI clients use delegates the actual responsibility of transaction coordination to the transaction manager on the server.
A client, such as an applet, can obtain a reference to the
TransactionManager objects using JNDI. A client can begin a transaction using either object reference. To get the
Transaction object for the current thread, the client program must invoke the
Checked transaction behavior provides transaction integrity by guaranteeing that a
commit does not succeed unless all transactional objects involved in the transaction have completed the processing of their transactional requests. The Transaction Service provides checked transaction behavior that is equivalent to that provided by the request/response inter-process communication models defined by The Open Group.
WebLogic Server allows transactions to be terminated only by the client that created the transaction.
The client may be a server object that requests the services of another object.
WebLogic Server implements the flat transaction model. Nested transactions are not supported.
Relationship of the Transaction Service to Transaction Processing
The Transaction Service relates to various transaction processing servers, interfaces, protocols, and standards in the following ways:
Support for The Open Group XA interface.The Open Group Resource Managers are resource managers that can be involved in a distributed transaction by allowing their two-phase commit protocol to be controlled using The Open Group XA interface. WebLogic Server supports interaction with The Open Group Resource Managers.
Support for the OSI TP protocol. Open Systems Interconnect Transaction Processing (OSI TP) is the transactional protocol defined by the International Organization for Standardization (ISO). WebLogic Server does not support interactions with OSI TP transactions.
Support for the LU 6.2 protocol. Systems Network Architecture (SNA) LU 6.2 is a transactional protocol defined by IBM. WebLogic Server does not support interactions with LU 6.2 transactions.
Support for the ODMG standard. ODMG-93 is a standard defined by the Object Database Management Group (ODMG) that describes a portable interface to access Object Database Management Systems. WebLogic Server does not support interactions with ODMG transactions.
Multithreaded Transaction Client Support
WebLogic Server supports multithreaded transactional clients. Clients can make transaction requests concurrently in multiple threads.
The Transaction Service assigns a transaction identifier (
XID) to each transaction. This ID can isolate information about a specific transaction in a log file. You can retrieve the transaction identifier using the
getXID method in the
weblogic.transaction.Transaction interface. For detailed information on methods for getting the transaction identifier, see
weblogic.transaction.Transaction in the Java API Reference for Oracle WebLogic Server.
Transaction Name and Properties
WebLogic JTA provides extensions to
javax.transaction.Transaction that support transaction naming and user-defined properties. These extensions are included in the
The transaction name indicates a type of transaction (for example, funds transfer or ticket purchase) and should not be confused with the transaction ID, which identifies a unique transaction on a server. The transaction name makes it easier to identify a transaction type in the context of an exception or a log file.
User-defined properties are key/value pairs, where the key is a string identifying the property and the value is the current value assigned to the property. Transaction property values must be objects that implement the
Serializable interface. You manage properties in your application using the set and get methods defined in the
weblogic.transaction.Transaction interface. Once set, properties stay with a transaction during its entire lifetime and are passed between machines as the transaction travels through the system. Properties are saved in the transaction log, and are restored during crash recovery processing. If a transaction property is set more than once, the latest value is retained.
For detailed information on methods for setting and getting the transaction name and transaction properties, see
weblogic.transaction.Transaction in the Java API Reference for Oracle WebLogic Server.
The Java Transaction API provides transaction status codes using the
javax.transaction.Status class. Use the
getStatusAsString method in
weblogic.transaction.Transaction to return the status of the transaction as a string. The string contains the major state as specified in
javax.transaction.Status with an additional minor state (such as
Transaction statistics are provided for all transactions handled by the transaction manager on a server. These statistics include the number of total transactions, transactions with a specific outcome (such as committed, rolled back, or heuristic completion), rolled back transactions by reason, and the total time that transactions were active. For detailed information on transaction statistics, see Monitoring Transactions.
The following constraints apply to the Transaction Service:
In WebLogic Server, a client or a server object cannot invoke methods on an object that is infected with (or participating in) another transaction. The method invocation issued by the client or the server instance returns an exception.
In WebLogic Server, clients using third-party implementations of the Java Transaction API (for Java applications) are not supported.
The transaction log buffer is limited to 250 KB. If your application includes very large transactions that require transaction log writes that exceed this value, WebLogic Server instance throws an exception. In that case, you must reconfigure your application to work around the buffer size.
The scope of a transaction refers to the environment in which the transaction is performed. WebLogic Server supports transactions on standalone servers, between non-clustered servers, between clustered servers within a domain, and between domains.
To enable inter-domain transaction support, see Configuring Secure Inter-Domain and Intra-Domain Transaction Communication.
Transaction Service in EJB Applications
The WebLogic Server EJB container provides a Transaction Service that supports the two types of transactions in WebLogic Server EJB applications such as container-managed transactions and bean-managed transactions.
Container-managed transactions. In container-managed transactions, the WebLogic Server EJB container manages the transaction demarcation. Transaction attributes in the EJB deployment descriptor determine how the WebLogic Server EJB container handles transactions with each method invocation.
Bean-managed transactions. In bean-managed transactions, the EJB manages the transaction demarcation. The EJB makes explicit method invocations on the
UserTransactionobject to begin, commit, and roll back transactions. For more information about
weblogic.transaction.UserTransactionin the Java API Reference for Oracle WebLogic Server.
Transaction Service in RMI Applications
WebLogic Server provides a Transaction Service that supports transactions in WebLogic Server RMI applications. In RMI applications, the client or server application makes explicit method invocations on the
UserTransaction object to begin, commit, and roll back transactions.
For more information about
UserTransaction methods, see the online javadoc. For an introduction to transaction management in RMI applications, see Transactions in WebLogic Server RMI Applications and Transactions Sample RMI Code.
Transaction Service Interoperating with OTS
WebLogic Server provides a Transaction Service that supports interoperation with the Object Transaction Service (OTS).
See the Java Transaction Service (JTS) Specification at
http://www.oracle.com/technetwork/java/javaee/jts-spec095-1508547.pdf. For this release, WebLogic Server interoperates with OTS in the following scenarios:
In this situation, a server-to-server 2PC transaction is completed using interposition. The originating server creates an Xid and propagates the transaction to the target server. The target server registers itself as a resource with the originating server. The originating server drives the completion of the transaction. Logging Last Resource (LLR) transaction optimization, as described in Logging Last Resource Transaction Optimization, is not supported.
Client Demarcated Transactions
The client starts a transaction on the server using the OTS client APIs. The client then retrieves the Xid from this transaction and then propagates this per-request until the transaction is committed. Although the client initiates the transaction, all the commit processing occurs on the server.