Oracle Tips by Burleson

Oracle Streams
Chapter 1 - What is Streams?

Where to use Streams

RAC, Data Guard and Streams offer different solutions. Each methodology has its strengths, but the Streams methodology has cleverly incorporated some of the strengths of RAC and Data Guard.

Message Queuing

By using the Streams based Advanced Queuing (AQ), user applications can enqueue messages into queues, then propagate them to the subscribing queues. The AQ process sends notifications when messages arrive into queues, allowing the specified action routine to execute. Usually, the action routine involves processing the messages by de-queuing them at the destination.

Oracle AQ has all the standard features of the message queuing systems. It allows the establishment of multi-consumer queues, publish and subscribe methodology, content based routing, transformations, and gateways to other messaging subsystems. Oracle Streams based AQ is fully integrated into the database systems. As a result, the maintenance of persistent queues becomes really robust.  AQ stores the messages in the database objects in a transactional order. The messages are available later, even after they are de-queued, for secondary uses like auditing and tracking. This is one of the main reasons for the popularity of AQ.

Event Messaging and Notification

Business organizations need to propagate a variety of messages between different applications running on different systems and supporting a variety of business users. Events are basic units of business communications that convey a certain message, situation, or status, which in turn could trigger a specified action. The alert mechanism or notification mechanism is built upon the simple premise of a cause and effect paradigm.