What's New in Advanced Queuing?

This section describes the new Advanced Queuing features of Oracle9i and previous releases.

The following sections describe the new features in Oracle Advanced Queuing:

• Oracle9i Release 2 (9.2.0) New Features
• Oracle9i (9.0.1) New Features in Advanced Queuing
• Oracle8i New Features in Advanced Queuing

Oracle9i Release 2 (9.2.0) New Features

• Oracle Messaging Gateway

  The interaction between different messaging systems is a common integration requirement. Messaging Gateway allows Advanced Queuing to propagate messages to and from non-Oracle messaging systems. It allows secure, transactional, and guaranteed one-time-only delivery of messages between Oracle Advanced Queuing and IBM MQSeries v5.1 and v5.2. See Chapter 18, "Messaging Gateway" for more information.

• Standard JMS Support

  Oracle's JMS implementation conforms to Sun Microsystems' JMS 1.0.2b standard. See "J2EE Compliance".

• XMLType Payload Support

  You no longer need to embed an XMLType attribute in an Oracle object type. You can directly use an XMLType message as the message payload.

Oracle9i (9.0.1) New Features in Advanced Queuing

Oracle9i introduces the following new Advanced Queuing features to improve e-business integration and use standard Internet transport protocols:

• Internet Integration

  To perform queuing operations over the Internet, Advanced Queuing takes advantage of the Internet Data Access Presentation (IDAP), which defines message structure using XML. Using IDAP, AQ operations such as enqueue, dequeue, notification, and propagation can be executed using standard Internet transport protocols--HTTP(S) and SMTP. Third-party clients, including third-party messaging vendors, can also interoperate with AQ over the Internet using Messaging Gateway.

  IDAP messages can be requests, responses, or an error response. An IDAP document sent from an AQ client contains an attribute for designating the remote operation; that is, enqueue, dequeue, or register accompanied by operational data. The AQ implementation of IDAP can also be used to execute batched enqueue and dequeue of messages.

  The HTTP and SMTP support in AQ is implemented by using the AQ servlet which is bundled with the Oracle database server. A client invokes the servlet through an HTTP post request that is sent to the Web server. The Web server invokes the servlet mentioned in the post method if one is not already invoked. The servlet parses the content of the IDAP document and uses the AQ Java API to perform the designated operation. On completion of the call, the servlet formats either a response or an error response as indicated by IDAP and sends it back to the client.

  IDAP is transport independent and therefore can work with other transport protocols transparently. Oracle9i supports HTTP and SMTP; other proprietary protocols can also be supported using the callout mechanism through transformations.

• Advanced Queuing Security over the Internet

  AQ functionality allows only authorized Internet users to perform AQ operations on AQ queues. An Internet user connects to a Web server, which in turn connects to the database using an application server. The Internet user doing the operation is typically not the database user connected to the database. Also, the AQ queues may not reside in the same schema as the connected database user. Advanced Queuing uses proxy authentication so that only authorized Internet users can perform AQ operations on AQ queues.

• LDAP Integration

  OID Integration: To leverage LDAP as the single point for managing generic information, Advanced Queuing is integrated with the Oracle Internet Directory (OID) server. This addresses the following requirements:

  • Global topics (queues): AQ queue information can be stored in an OID server. OID provides a single point of contact to locate the required topic or queue. Business applications (users) looking for specific information need not know in which database the queue is located. Using the industry standard Java Messaging Service (JMS) API, users can directly connect to the queue without explicitly specifying the database or the location of the topic or queue.
  • Global events: OID can be used as the repository for event registration. Clients can register for database events even when the database is down. This allows clients to register for events such as "Database Open," which would not have been possible earlier. Clients can register for events in multiple databases in a single request.

  XML Integration: XML has emerged as a standard for e-business data representations. The XMLType datatype has been added to the Oracle server to support operations on XML data. AQ not only supports XMLType data type payloads, but also allows definitions of subscriptions based on the contents of an XML message. This is powerful functionality for online market places where multiple vendors can define their subscriptions based on the contents of the orders.

• Transformation Infrastructure

  Applications are designed independent of each other. So, the messages they understand are different from each other. To integrate these applications, messages have to be transformed. There are various existing solutions to handle these transformations. AQ provides a transformation infrastructure that can be used to plug in transformation functionality from Oracle Application Interconnect or other third-party solutions such as Mercator without losing AQ functionality. Transformations can be specified as PL/SQL call back functions, which are applied at enqueue, dequeue, or propagation of messages. These PL/SQL callback functions can call third-party functions implemented in C, Java, or PL/SQL. XSLT transformations can also be specified for XML messages.

• AQ Management

  You can use new and enhanced Oracle Enterprise Manager to manage Advanced Queuing, as follows:

  • Improved UI task flow and administration of queues, including a topology display at the database level and at the queue level, error and propagation schedules for all the queues in the database, and relevant initialization parameters (init.ora)
  • Ability to view the message queue

  Oracle diagnostics and tuning pack supports alerts and monitoring of AQ queues. Alerts can be sent when the number of messages for a particular subscriber exceeds a threshold. Alerts can be sent when there is an error in propagation. In addition, queues can be monitored for the number of messages in ready state or the number of messages per subscriber.

• Additional Enhancements

  PL/SQL notifications and e-mail notifications: Oracle9i allows notifications on the queues to be PL/SQL functions. Using this functionality, users can register PL/SQL functions that will be called when a message of interest is enqueued. Using e-mail notification functionality, an e-mail address can be registered to provide notifications. E-mail will be sent if the message of interest arrives in the queue. Presentation of the e-mail message can also be specified while registering for e-mail notification. Users can also specify an HTTP URL to which notifications can be sent.

  Dequeue enhancements: Using the dequeue with a condition functionality, subscribers can select messages that satisfy a specified condition from the messages meant for them.

  Overall performance improvements: AQ exhibits overall performance improvements as a result of code optimization and other changes.

  Propagation enhancements: The maximum number of job queue processes has been increased from 36 to 1000 in Oracle9i. With Internet propagation, you can set up propagation between queues over HTTP. Overall performance improvements have been made in propagation due to design changes in the propagation algorithm.

• JMS Enhancements

  All the new Oracle9i features are supported through JMS, as well as the following:

  • Connection pooling: Using this feature, a pool of connection can be established with the Oracle database server. Later, at the time of establishing a JMS session, a connection from the pool can be picked up.
  • Global topics: This is the result of the integration with Oracle Internet Directory. AQ Queue information can be stored and looked up from OID.
  • Topic browsing: Allows durable subscribers to browse through the messages in a publish-subscribe (topic) destination, and optionally allows these subscribers to purge the browsed messages (so that they are no longer retained by AQ for that subscriber).
  • Exception listener support: This allows a client to be asynchronously notified of a problem. Some connections only consume messages, so they have no other way to learn that their connection has failed.

Oracle8i New Features in Advanced Queuing

The Oracle8i release included the following Advanced Queuing features:

• Queue-level access control
• Nonpersistent queues
• Support for Oracle Parallel Server
• Rule-based subscribers for publish-subscribe
• Asynchronous notification
• Sender identification
• Listen capability (wait on multiple queues)
• Propagation of messages with LOBs
• Enhanced propagation scheduling
• Dequeuing message headers only
• Support for statistics views
• Java API (native AQ)
• Java Messaging Service (JMS) API
• Separate storage of history management information