Using AQ Java (oracle.AQ) Classes to Access AQ

Java AQ API supports both the administrative and operational features of Oracle AQ (Advanced Queueing). In developing Java programs for messaging applications, you will use JDBC to open a connection to the database and then the oracle.AQ, the Java AQ API for message queuing. This means that you will no longer need to use PL/SQL interfaces.

Oracle9i Supplied Java Packages Reference describes the common interfaces and classes based on current PL/SQL interfaces.

• Common interfaces are prefixed with "AQ". These interfaces will have different implementations in Oracle8i and Oracle Lite.

• In this document we describe the common interfaces and their corresponding Oracle8i implementations, that are in turn prefixed with "AQOracle".

Accessing Java AQ Classes

The Java AQ classes are located in $ORACLE_HOME/rdbms/jlib/aqapi.jar. These classes can be used with any Oracle8i JDBC driver.

• Using OCI8 or Thin JDBC Driver: If your application uses the OCI8 or thin JDBC driver:
  • For JDK 1.2 you must include $ORACLE_HOME/rdbms/jlib/aqapi.jar in the CLASSPATH

  • For JDK 1.1 you must include $ORACLE_HOME/rdbms/jlib/aqapi11.jar in the CLASSPATH.

• Using Oracle Server Driver in JServer: If the application is using the Oracle Server driver and accessing the java AQ API from java stored procedures, the Java files are generally automatically pre-loaded in a Java-enabled database. If the Java files are not loaded, you must first load the jmscommon.jar and aqapi.jar files into the database using the "loadjava" utility.

Advanced Queuing Examples

Appendix A, "Oracle Advanced Queuing by Example" contains the following examples:

• Enqueue and Dequeue of Object Type Messages (CustomDatum interface) Using Java

• Enqueue and Dequeue of Object Type Messages (using SQLData interface) Using Java

• Create a Queue Table and Queue Using Java

• Create a Queue and Start Enqueue/Dequeue Using Java

• Create a Multi-Consumer Queue and Add Subscribers Using Java

• Enqueue of RAW Messages using Java

• Dequeue of Messages Using Java

• Dequeue of Messages in Browse Mode Using Java

• Enqueue of Messages with Priority Using Java

• Enqueuing and Dequeuing Object Type Messages That Contain LOB Attributes Using Java

Managing the Java AQ API

The various implementations of the Java AQ API are managed via an AQDriverManager. Both OLite and Oracle9i will have an AQDriver that is registered with the AQDriverManager. The driver manager is used to create an AQSession that can be used to perform messaging tasks.

The Oracle8i AQ driver is registered using the Class.forName ("oracle.AQ.AQOracleDriver") command.

When the AQDriverManager.createAQSession() method is invoked, it calls the appropriate AQDriver (amongst the registered drivers) depending on the parameter passed to the createAQSession() call.

The Oracle9i AQDriver expects a valid JDBC connection to be passed in as a parameter to create an AQSession. Users must have the execute privilege on the DBMS_AQIN package to use the AQ Java interfaces. Users can also acquire these rights through the AQ_USER_ROLE or the AQ_ADMINSTRATOR_ROLE. Users will also need the appropriate system and queue privileges for 8.1-style queue tables.