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Migrating WebLogic JMS Applications

The following sections describe how to migrate WebLogic JMS applications:

- Existing Feature Functionality Changes

- Migrating Existing Applications

- Deleting JDBC Database Stores

Existing Feature Functionality Changes

Changes in existing feature functionality have been made in order to comply with the JavaSoft JMS Specification version 1.0.2. and the latest JMS API - Errata. Therefore, you should check feature functionality changes in the following tables before beginning any migration procedures:

- Existing Feature 5.1 to 6.0 Functionality Changes

- Existing 6.0 to 6.1 Feature Functionality Changes

The following table lists the changes in existing feature functionality from WebLogic Server version 5.1, and also indicates any code changes that might be required as a result. For additional information pertaining to the version 1.0.2 change history, see Chapter 11, "Change History," of the JavaSoft JMS Specification version 1.0.2.

Table 6-1 Existing Feature 5.1 to 6.0 Functionality Changes

Category | Description | Code Modification
--- | --- | ---
Connection Factories | Two default connection factories have been deprecated. The JNDI names for these factories are: javax.jms.QueueConnectionFactory javax.jms.TopicConnectionFactory For backwards compatibility, the JNDI names for these two connection factories are still defined and supported. WebLogic JMS 6.x defines one default connection factory. It can be looked up using the JNDI name, weblogic.jms.ConnectionFactory. You can also specify user-defined connection factories using the Administration Console. Note: Using the default connection factory, you have no control over the WebLogic server on which the connection factory may be deployed. If you would like to target a particular WebLogic Server, create a new connection factory and specify the appropriate WebLogic Server target(s). | It is recommended that existing code that use the deprecated classes be modified to use a new default or user-defined connection factory class. For example, if your code specified the following constant using the default queue connection factory: public final static String JMS_FACTORY="javax.jms.QueueConnectionFactory" You should modify the constant to use a new user-defined connection factory, for example: public final static String JMS_FACTORY="weblogic.jms.QueueConnectionFactory" For true backwards compatibility with previous releases, you should ensure that you select the Allow Close In onMessage and User Transactions Enabled check boxes when configuring the connection factory. For more information about defining connection factories, see "JMS Connection Factories" in the Administration Console Online Help.
In order to instantiate the default connection factory on a particular WebLogic Server, you must select the Enable Default JMS Connection Factories check box when configuring the WebLogic Server. | None required. This is a configuration requirement. For more information, see "Server" in the Administration Console Online Help.
Connections | When closing a connection, the call blocks until outstanding synchronous calls and asynchronous listeners have completed. | None required.
Sessions | When closing a session, the call blocks until outstanding synchronous calls and asynchronous listeners have completed. | None required.
Message Consumers | If multiple topic subscribers are defined in the same session for the same topic, each consumer will receive its own copy of a message. | None required.
When closing a message consumer, the call blocks until the method call completes and any outstanding synchronous applications are cancelled. | None required.
In order to comply with the JMS specification, if the close() method is called from within an onMessage() method, the application will hang unless the Allow Close In OnMessage check box is selected when configuring the connection factory. If the acknowledge mode is AUTO_ACKNOWLEDGE, the current message will still be automatically acknowledged. | None required. This is a configuration requirement. For more information, see "JMS Connection Factories" in the Administration Console Online Help.
Message Header Field | The JMSMessageID header field format has changed. | If you wish to access existing messages using the JMSMessageID, you may need to run one of the following weblogic.jms.extensions.JMSHelper methods to convert between WebLogic pre-JMS 5.1 and JMS 6.x JMSMessageID formats. To convert from pre-5.1 to 6.x JMSMessageID format: public void oldJMSMessageIDToNew( String id, long timeStamp ) throws JMSException To convert from 6.1 to pre- 6.1 JMSMessageID format: public void newJMSMessageIDToOld( String id, long timeStamp ) throws JMSException
Destinations | The createQueue() and createTopic() methods do not create destinations dynamically, only references to destinations that already exist given the vendor-specific destination name. | Update any portion of code that uses createQueue() or createTopic() to dynamically create destinations using the following JMSHelper class methods, respectively: createPermanentQueueAsync() and createPermanentTopicAsync(). For example, if your code used the following method to dynamically create a queue: queue=qsession.createQueue(queueName); You should modify the code to dynamically create a queue, as described in the sample findQueue() method in Using the JMSHelper Class Methods. For more information on the JMSHelper classes, see Creating Destinations Dynamically.
When creating temporary destinations, you must specify a temporary template. | None required. This is a configuration requirement. For more information, see "JMS Templates" in the Administration Console Online Help.
You must be the owner of the connection in order to create a message consumer for that temporary destination. | When creating a message consumer on a temporary destination, ensure that you are the owner of the connection.
Durable Subscribers | You no longer need to manually create JDBC tables for durable subscribers. They are created automatically. | None required.
There is no limit on the number of durable subscribers that can be created. | None required.
When defining a client ID programatically, it must be defined immediately after creating a connection. Otherwise, an exception will be thrown and you will be unable to make any other JMS calls on that connection. | Ensure that the setClientID() method is issued immediately after creating the connection. For more information, refer to Defining the Client ID.
Session Pools | Session pool factories, session pools, referenced connection factories, referenced destinations, and associated connection consumers must all be targeted on the same JMS server. | Ensure that all objects are targeted on the same JMS server.
The SessionPoolManager and ConnectionConsumerManager interfaces that were published as part of the WebLogic JMS version 5.1 Javadoc have been removed from the version 6.0 and 6.1 Javadoc, as they are system interfaces and should not be used within client applications. | If used, remove any references to these objects from the client application.
Transactions | To combine JMS and EJB database calls within the same transaction, a two-phase commit (2PC) license is required. In previous releases of WebLogic Server, it was possible to combine them by using the same database connection pool. | None required.
Recovering or rolling back received queue messages makes them available to all consumers on the queue. In previous releases of WebLogic Server, rolled back messages were only available to the session that rolled back the message, until that session was closed. | None required.

The following table lists the changes in existing feature functionality from WebLogic Server version 6.0, and also indicates any code changes that might be required as a result. For additional information pertaining to the version 1.0.2 change history, see Chapter 11, "Change History," of the JavaSoft JMS Specification version 1.0.2

Table 6-2 Existing 6.0 to 6.1 Feature Functionality Changes

Category | Description | Code Modification
--- | --- | ---
Connection Factories | For the Acknowledge Policy attribute in the Administration Console, the new default value of All is a work-around to accommodate a change in the JavaSoft JMS Specification. This new default setting represents a change from prior versions of JMS, which internally defaulted to Previous, and which did not appear as an option in the Administration Console. As the message acknowledge policy for the connection factory, the Acknowledge Policy attribute only applies to implementations that use the CLIENT_ACKNOWLEDGE mode for a non-transacted session. All — acknowledge all messages ever received by a given session, regardless of which message calls the acknowledge method. Previous — acknowledge all messages received by a given session, but only up to and including the message that calls the acknowledge method. For more information on message acknowledge modes, refer to Non-transacted Session. Note: For connection factories used by MDBs (message-driven beans), always set the Acknowledge Policy field to Previous. Although the default MDB connection factory already does this, foreign connection factories may not. | If you want to acknowledge only previously received messages, up to and including the message that calls the acknowledge method, change the default Acknowledge Policy setting from All to Previous via the JMS Connection Factories tab in the Administration Console.
Destinations | In WLS version 6.0, the JMS documentation correctly specifies values of default, true, and false for the StoreEnabled attribute of the JMSDestinationMBean, even though the software allowed for mixed case characters. version 6.1, however, requires all lowercase characters for the StoreEnabled settings. | None required. This is a configuration requirement. For more information, see "JMS Templates" in the Administration Console Online Help.
Session Pools | In WebLogic Server 6.0 SP2 or higher, for the QueueConnection and TopicConnection classes, the MaxMessages argument in the createConnectionConsumer method now requires a specific value for the amount of messages to be reserved on the server. Therefore, MaxMessages will be parsed as follows: -1 - The same as the default value, which is 10. >0 - Positive integers require no conversion. 0 - An invalid value that will generate a JMSException. <-1 - An invalid value that will generate a JMSException. | In the createConnectionConsumer method, ensure that the value of the MaxMessages argument is set to either -1 (the default) or a positive integer.

Migrating Existing Applications

WebLogic Server 6.1 supports the JavaSoft JMS Specification version 1.0.2. and the latest JMS API - Errata. In order to use your existing JMS applications, you must first confirm your version of WebLogic server, and then perform the appropriate migration procedures provided in this section.

Before You Begin

Before beginning the migration procedure, you should check the following list to confirm whether migration is support for your version of WebLogic Server JMS, and to find out whether special migration rules apply to that release:

- Version 4.5 — Migration is supported only for SP14. Customers running all service packs should contact BEA Support.

- Version 5.1 — Customers running with SP07 or SP08 should contact BEA Support before migrating existing JDBC stores to versions 6.0 or 6.1.

  - In order to migrate object messages, the object classes need to be in the version 6.0 or higher server classpath.

  - For destinations that are not configured in release 6.0 or higher, the migrated messages will be dropped and the event will be logged.

- Version 6.0 — Migration to version 6.1 or higher is supported for all service packs. However, administrators should read about the change to the Acknowledge Policy attribute default.

  - For the Acknowledge Policy attribute in the WebLogic JMS version 6.1 Connection Factory, the default value of All is a work around to accommodate a change in the JavaSoft JMS Specification. For more information, refer to the Connection Factory category in the Existing 6.0 to 6.1 Feature Functionality Changes.

Migration Steps for 4.5 and 5.1 Applications to 6.x

Before you can use an existing WebLogic JMS 6.x application, you must migrate the WebLogic Server versions 4.5 and 5.1 configuration and message data as follows:

1. Properly shut down the old version of WebLogic Server before beginning the migration process.

   Warning: Abruptly stopping the old version of WebLogic Server while messaging is still in process may cause problems during migration. Processing should be inactive before shutting down the old server and beginning the migration to WebLogic Server version 6.x.

2. Upgrade the WebLogic Server environment, as described in Installing WebLogic Server.

3. Migrate configuration information using the configuration conversion facility.

   During the configuration migration, the following default queue and topic connection factories are enabled:

   - javax.jms.QueueConnectionFactory

   - javax.jms.TopicConnectionFactory

   - weblogic.jms.ConnectionFactory

     The first two connection factories are deprecated, but they are still defined and usable for backwards compatibility. For information on the new default connection factory, see the table Existing Feature 5.1 to 6.0 Functionality Changes.

     The JMS administrator will need to review the resulting configuration to ensure that the conversion meets the needs of the application. In this case, all of the JMS attributes will be mapped to a single node, as in version 5.1.

     Note: In versions 6.0 or higher, JMS queues are defined during configuration, and no longer saved within database tables. Message data and durable subscriptions are stored either in two JDBC tables or via a directory within the file system.

4. Prepare for automatic migration of existing JDBC database stores.

   1. Make a backup of the existing JDBC database.

   2. Ensure that the migrated configuration information (see step 2) contains a JDBC database store with exactly the same attributes as the existing store, and that the new JMS servers that use the store define the same destinations and corresponding destination attributes as the existing JMS servers.

   3. If the new JDBC database store already exists, ensure that it is empty.

      The new JDBC database store will be created during the automatic migration, if required.

   4. Ensure that there is twice the amount of disk space required by the JDBC database store available on the system.

      Both the existing and new database information will exist on disk while the migration is performed, doubling the space requirements. Once migration is complete, you can delete the old JDBC database stores, as described in Deleting JDBC Database Stores.

5. Update any existing code, as required, to reflect the feature functionality changes described in Existing Feature 5.1 to 6.0 Functionality Changes.

6. Start up the WebLogic Server and the existing JDBC database stores will be migrated automatically.

   Note: If the automatic migration fails for any reason, the automatic migration will be re-attempted the next time the WebLogic Server boots.

Migration Steps for 6.0 Applications to 6.1

Before you can use an existing WebLogic JMS 6.x application, you must migrate the WebLogic Server version 6.0 configuration and message data as follows

1. Check the connection factory configuration for version 6.0. You may need to modify programs that call the new 6.1 default connection factory so that they load one of the following connection factories:

   - One of the version 6.0 default connection factories.

   - A custom connection factory.

2. Properly shut down the version 6.0 WebLogic Server before beginning the migration process.

   Warning: Abruptly stopping the old version of WebLogic Server while messaging is still in process may cause problems during migration. Processing should be inactive before shutting down the old server and beginning the migration to WebLogic Server version 6.x.

3. Upgrade the WebLogic Server environment, as described in Installing WebLogic Server.

4. Update any existing code, as required, to reflect the feature functionality changes described in Existing 6.0 to 6.1 Feature Functionality Changes.

   Warning: Before starting the 6.1 WebLogic Server, you may want to backup your version 6.0 stores. This is because version 6.0 servers cannot use 6.1 stores, and any attempts to do so may cause data corruption.

5. Start up the version 6.1 WebLogic Server. The 6.1 server will continue to use the previous version 6.0 stores.

Deleting JDBC Database Stores

Once the migration is complete, the old JDBC database tables should be removed using the utils.Schema utility, described in detail in JDBC Database Utility.

During migration, a DDL file is generated and stored in the local working directory. The DDL file is named drop_<jmsServerName>_oldtables.ddl, where <jmsServerName> specifies the name of the JMS server. To delete the JDBC database stores, you pass the resulting DDL file as an argument to the utils.Schema utility.

For example, to delete the old JDBC database store from a JMS server named MyJMSServer, execute the following command:

>     java utils.Schema jdbc:weblogic:oracle weblogic.jdbc.oci.Driver -s server -u
>     user1 -p foobar -verbose drop_MyJMSServer_oldtables.ddl

For more information on the utils.Schema utility, see JDBC Database Utility.

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