Introduction to Oracle Advanced Queue

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Introduction to OracleAdvanced Queue

Release Version 0.1

Tata Consultancy ServicesBangalore

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By

Rakesh P.A


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Table of Contents

1.INTRODUCTION.....................................................................................................................................................1

1.1. ADVANCED QUEUE........................................................................................................................................... 1

1.2. HISTORY......................................................................................................................................................... 1

1.3. DOCUMENTS GOAL: .........................................................................................................................................1

2.ORACLE ADVANCED QUEUE............................................................................................................................1

2.1. OVERVIEW.......................................................................................................................................................1

2.2. PRODUCERS.....................................................................................................................................................1

2.3. QUEUES........................................................................................................................................................... 1

2.4. QUEUE-TO-QUEUE TRANSMISSION: ......................................................................................................................4

3.CONCLUSION..........................................................................................................................................................7

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1. Introduction

1.1. Advanced Queue

Advanced Queuing (AQ) apart from managing all the data inside the Oracle

database, can also manage the flow and exchange of data using messagesto different systems. Message queuing functionality is natively used insidethe database. AQ leverages this Message queuing functionality. AQprovides easy manageability, high availability, high performance andsecurity. AQ supports point-to-point and publish/subscribe queues,persistent and buffered messaging, and message ordering priorities thatoffer flexibility and powerful messaging functionality to applications.

1.2. History

Oracle AQ was introduced in Oracle 8.

Since release 10.1, AQ is integrated into Oracle Streams, and is called"Oracle Streams AQ".

1.3. Documents Goal:

The goal of this document is to give an Introduction to features of OracleAdvanced Queue.

2. Oracle Advanced Queue

2.1. Overview

Producer applications enqueue messages and consumer applicationsdequeue messages. At the most basic level of queuing, one producerenqueues one or more messages into one queue. Each message isdequeued and processed once by one of the consumers.

2.2. Producers

Database triggers, batch jobs, external applications and JWS queues can

serve as producers.

2.3. Queues

Every queue must be associated with a queue table. Queue table definesproperties of queue. Queue table are reported in DBA_QUEUE_TABLES.Queue tables are managed using DBMS_AQADM.

Tata Consultancy Services Internal Use Only Page 1 of 12
http://www.orafaq.com/wiki/Oracle_8http://www.orafaq.com/wiki/Oracle_Streamshttp://www.orafaq.com/wiki/Oracle_Streamshttp://www.orafaq.com/wiki/Oracle_8


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There are four types of queues:

1) Single Consumer Queue

2) Multiple-Consumer Queue

3) Buffered Queue

4) Persistent Queue

2.3.1. Single Consumer Queue

Fig (a) Single Consumer Queue



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2.3.2. Multiple-Consumer Queue

Fig (b) Multiple Consumer Queue

2.3.3. Buffered Queue

Buffered messaging combines the rich functionality that Oracle

Streams AQ has always offered with a much faster queuing imple-mentation. Buffered messaging is faster than persistent messaging,because its messages reside in shared memory. They are usuallywritten to disk only when the total memory consumption of bufferedmessages approaches the available shared memory limit. Bufferedmessaging is ideal for applications that do not require the reliabilityand transaction support of Oracle Streams AQ persistent messaging.



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The portion of a queue that stores buffered messages in memory issometimes referred to as a buffered queue. Message retention isnot supported for buffered messaging.

2.3.4. Persistent Queue

When persistent messages are enqueued, they are stored in data-base tables. The performance characteristics ofqueue operations onpersistent messages are similar to underlying database operations.The code path of an enqueue operation is comparable to SE-LECT and INSERT into a multicolumn queue table with three index-organized tables. The code path of a dequeue operation is compara-ble to a SELECT operation on the multi-column table anda DELETE operation on the dequeue index-organized table. In manyscenarios, for example when Oracle Real Application Clusters (Ora-

cle RAC) is not used and there is adequate streams pool memory,the dequeue operation is optimized and is comparable to a SE-LECT operation on a multi-column table.

2.4. Queue-to-Queue Transmission:

The technique for transmitting the messages from one queue to another iscalledPropagation. There are various usages for propagation.

Fig (c) Queue-to-Queue Transmission

http://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAHIIABhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAJCGCHhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAFHDDDhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAGEGIFhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAHIIABhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAJCGCHhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAFHDDDhttp://blog.ronnyegner-consulting.de/wp-content/uploads/oracle_docs/DB_11gR2/server.112/e11013/glossary.htm#CBAGEGIF


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2.4.1. Fanning-Out Messages

This technique is normally used in case of multi-database architec-ture where load balancing of message sending has to be achieved.Whenever message is enqueued in HQ queue, it is propagated toRegional 1 and 2 queues. The Regional 1 and 2 queues in turn willpropagate the messages to their respective subscribers. There arerule based propagations that makes this happen.

Fig (d) Queue-to-Queue Transmission



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2.4.2. Funneling-In Messages

The other technique of propagating messages is the reverse of fan-ning. Here the Users will be propagating messages to Regional andit in turn will propagate to HQ queue. This method is called Funnel-ing in messages.



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Fig (e) Queue-to-Queue Transmission

3. Conclusion

Oracle Advanced Queuing, built into the Oracle Database, offers a robustplatform to standardize and integrate the various technologies and applica-

tions inside the datacenter. Businesses can leverage the AQs enterprisemessaging infrastructure to build highly scalable and reliable distributedapplications. Powerful AQ features such as differing qualities of service, au-tomatic message transformations, and propagations give businesses thetools needed to design a powerful and flexible messaging platform. Data-base integrated Advanced Queuing provides smooth, real-time flow of criti-



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cal information, less management and more productivity for your evergrowing, scalable, highly available business.
