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diff --git a/qpid/doc/book/src/java-broker/Use-Priority-Queues.xml b/qpid/doc/book/src/java-broker/Use-Priority-Queues.xml deleted file mode 100644 index 466d958d43..0000000000 --- a/qpid/doc/book/src/java-broker/Use-Priority-Queues.xml +++ /dev/null @@ -1,138 +0,0 @@ -<?xml version="1.0" encoding="utf-8"?> -<!-- - - Licensed to the Apache Software Foundation (ASF) under one - or more contributor license agreements. See the NOTICE file - distributed with this work for additional information - regarding copyright ownership. The ASF licenses this file - to you under the Apache License, Version 2.0 (the - "License"); you may not use this file except in compliance - with the License. You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, - software distributed under the License is distributed on an - "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY - KIND, either express or implied. See the License for the - specific language governing permissions and limitations - under the License. - ---> - -<section id="Priority-Queues"><title> - Use Priority Queues - </title> - - - <section role="h2" id="UsePriorityQueues-GeneralInformation"><title> - General - Information - </title> - <para> - The Qpid M3 release introduces priority queues into the Java - Messaging Broker, supporting JMS clients who wish to make use of - priorities in their messaging implementation. - </para><para> - There are some key points around the use of priority queues in - Qpid, discussed in the sections below. - </para> -<!--h2--></section> - <section role="h2" id="UsePriorityQueues-DefiningPriorityQueues"><title> - Defining - Priority Queues - </title> - <para> - You must define a priority queue specifically before you start to - use it. You cannot subsequently change a queue to/from a priority - queue (without deleting it and re-creating). - </para><para> - You define a queue as a priority queue in the virtualhost - configuration file, which the broker loads at startup. When - defining the queue, add a <priority>true</priority> - element. This will ensure that the queue has 10 distinct - priorities, which is the number supported by JMS. - </para><para> - If you require fewer priorities, it is possible to specify a - <priorities>int</priorities> element (where int is a - valid integer value between 2 and 10 inclusive) which will give - the queue that number of distinct priorities. When messages are - sent to that queue, their effective priority will be calculated - by partitioning the priority space. If the number of effective - priorities is 2, then messages with priority 0-4 are treated the - same as "lower priority" and messages with priority 5-9 are - treated equivalently as "higher priority". - </para> - <programlisting> -<queue> - <name>test</name> - <test> - <exchange>amq.direct</exchange> - <priority>true</priority> - </test> -</queue> -</programlisting> -<!--h2--></section> - - <section role="h2" id="UsePriorityQueues-Clientconfiguration-2Fmessagingmodelforpriorityqueues"><title> - Client configuration/messaging model for priority queues - </title> - <para> - There are some other configuration & paradigm changes which - are required in order that priority queues work as expected. - </para> - <section role="h3" id="UsePriorityQueues-Setlowprefetch"><title> - Set low pre-fetch - </title> - <para> - Qpid clients receive buffered messages in batches, sized - according to the pre-fetch value. The current default is 5000. - </para><para> - However, if you use the default value you will probably - <emphasis>not</emphasis> see desirable behaviour with messages of different - priority. This is because a message arriving after the pre-fetch - buffer has filled will not leap frog messages of lower priority. - It will be delivered at the front of the next batch of buffered - messages (if that is appropriate), but this is most likely NOT - what you need. - </para><para> - So, you need to set the prefetch values for your client - (consumer) to make this sensible. To do this set the java system - property max_prefetch on the client environment (using -D) before - creating your consumer. - </para><para> - Setting the Qpid pre-fetch to 1 for your client means that - message priority will be honoured by the Qpid broker as it - dispatches messages to your client. A default for all client - connections can be set via a system property: - </para> - <programlisting> --Dmax_prefetch=1 -</programlisting> - <para> - The prefetch can be also be adjusted on a per connection basis by - adding a 'maxprefetch' value to the <xref linkend="Connection-URL-Format"/> - </para> - <programlisting> -amqp://guest:guest@client1/development?maxprefetch='1'&brokerlist='tcp://localhost:5672' -</programlisting> - <para> - There is a slight performance cost here if using the receive() - method and you could test with a slightly higher pre-fetch (up to - 10) if the trade-off between throughput and prioritisation is - weighted towards the former for your application. (If you're - using OnMessage() then this is not a concern.) - </para> -<!--h3--></section> - <section role="h3" id="UsePriorityQueues-Singleconsumerpersession"><title> - Single - consumer per session - </title> - <para> - If you are using the receive() method to consume messages then - you should also only use one consumer per session with priority - queues. If you're using OnMessage() then this is not a concern. - </para> -<!--h3--></section> -<!--h2--></section> -</section> |