svn commit: r838928 [2/2] - in /websites/production/camel/content: book-component-appendix.html book-in-one-page.html cache/main.pageCache camel-2110-release.html jms.html

[bu...@apache.org]

Modified: websites/production/camel/content/jms.html
==============================================================================
--- websites/production/camel/content/jms.html (original)
+++ websites/production/camel/content/jms.html Tue Nov 20 14:23:15 2012
@@ -182,7 +182,7 @@ In Camel 2.8 onwards, the default settin
 
 <h4><a shape="rect" name="JMS-Mostcommonlyusedoptions"></a>Most commonly used options</h4>
 <div class="confluenceTableSmall"><div class="table-wrap">
-<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"> Option </th><th colspan="1" rowspan="1" class="confluenceTh"> Default Value </th><th colspan="1" rowspan="1" class="confluenceTh"> Description </th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>clientId</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Sets the JMS client ID to use. Note that this value, if specified, must be unique and can only be used by a single JMS connection instance. It is typically only required for durable topic subscriptions. You may prefer to use <a shape="rect" class="external-link" href="http://activemq.apache.org/virtual-destinations.html">Virtual Topics</a> instead. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>concurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>1</tt> </td><td colspan="1" rowspan="1" class
 ="confluenceTd"> Specifies the default number of concurrent consumers. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>disableReplyTo</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> If <tt>true</tt>, a producer will behave like a InOnly exchange with the exception that <tt>JMSReplyTo</tt> header is sent out and not be suppressed like in the case of <tt>InOnly</tt>. Like <tt>InOnly</tt> the producer will not wait for a reply. A consumer with this flag will behave like <tt>InOnly</tt>. This feature can be used to bridge <tt>InOut</tt> requests to another queue so that a route on the other queue will send it&#180;s response directly back to the original <tt>JMSReplyTo</tt>. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>durableSubscriptionName</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="c
 onfluenceTd"> The durable subscriber name for specifying durable topic subscriptions. The <tt>clientId</tt> option <b>must</b> be configured as well. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>maxConcurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>1</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Specifies the maximum number of concurrent consumers. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>maxMessagesPerTask</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>-1</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> The number of messages per task. -1 is unlimited. If you use a range for concurrent consumers (eg min &lt; max), then this option can be used to set a value to eg <tt>100</tt> to control how fast the consumers will shrink when less work is required. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>preserveMessageQos</tt> </td><td col
 span="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Set to <tt>true</tt>, if you want to send message using the QoS settings specified on the message, instead of the QoS settings on the JMS endpoint. The following three headers are considered <tt>JMSPriority</tt>, <tt>JMSDeliveryMode</tt>, and <tt>JMSExpiration</tt>. You can provide all or only some of them. If not provided, Camel will fall back to use the values from the endpoint instead. So, when using this option, the headers override the values from the endpoint. The <tt>explicitQosEnabled</tt> option, by contrast, will only use options set on the endpoint, and not values from the message header. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>replyTo</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Provides an explicit ReplyTo destination, which overrides any in
 coming value of <tt>Message.getJMSReplyTo()</tt>. If you do <a shape="rect" href="request-reply.html" title="Request Reply">Request Reply</a> over JMS then <b>make sure</b> to read the section <em>Request-reply over JMS</em> further below for more details, and the <tt>replyToType</tt> option as well. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>replyToType</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.9:</b> Allows for explicitly specifying which kind of strategy to use for replyTo queues when doing request/reply over JMS. Possible values are: <tt>Temporary</tt>, <tt>Shared</tt>, or <tt>Exclusive</tt>. By default Camel will use temporary queues. However if <tt>replyTo</tt> has been configured, then <tt>Shared</tt> is used by default. This option allows you to use exclusive queues instead of shared ones. See further below for more details, and especially the no
 tes about the implications if running in a clustered environment, and the fact that <tt>Shared</tt> reply queues has lower performance than its alternatives <tt>Temporary</tt> and <tt>Exclusive</tt>. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>requestTimeout</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>20000</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Producer only:</b> The timeout for waiting for a reply when using the InOut <a shape="rect" href="exchange-pattern.html" title="Exchange Pattern">Exchange Pattern</a> (in milliseconds). The default is 20 seconds. See below in section <em>About time to live</em> for more details. See also the <em>requestTimeoutCheckerInterval</em> option. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>selector</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Sets the JMS Selector, whic
 h is an SQL 92 predicate that is used to filter messages within the broker. You may have to encode special characters such as = as %3D <b>Before Camel 2.3.0</b>, we don't support this option in CamelConsumerTemplate </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>timeToLive</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> When sending messages, specifies the time-to-live of the message (in milliseconds). See below in section <em>About time to live</em> for more details. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>transacted</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Specifies whether to use transacted mode for sending/receiving messages using the InOnly <a shape="rect" href="exchange-pattern.html" title="Exchange Pattern">Exchange Pattern</a>. </td></tr><tr><td colspa
 n="1" rowspan="1" class="confluenceTd"> <tt>testConnectionOnStartup</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.1:</b> Specifies whether to test the connection on startup. This ensures that when Camel starts that all the JMS consumers have a valid connection to the JMS broker. If a connection cannot be granted then Camel throws an exception on startup. This ensures that Camel is not started with failed connections. From <b>Camel 2.8</b> onwards also the JMS producers is tested as well. </td></tr></tbody></table>
+<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"> Option </th><th colspan="1" rowspan="1" class="confluenceTh"> Default Value </th><th colspan="1" rowspan="1" class="confluenceTh"> Description </th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>clientId</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Sets the JMS client ID to use. Note that this value, if specified, must be unique and can only be used by a single JMS connection instance. It is typically only required for durable topic subscriptions. You may prefer to use <a shape="rect" class="external-link" href="http://activemq.apache.org/virtual-destinations.html">Virtual Topics</a> instead. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>concurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>1</tt> </td><td colspan="1" rowspan="1" class
 ="confluenceTd"> Specifies the default number of concurrent consumers. From Camel 2.11 onwards this option can also be used when doing request/reply over JMS. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>disableReplyTo</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> If <tt>true</tt>, a producer will behave like a InOnly exchange with the exception that <tt>JMSReplyTo</tt> header is sent out and not be suppressed like in the case of <tt>InOnly</tt>. Like <tt>InOnly</tt> the producer will not wait for a reply. A consumer with this flag will behave like <tt>InOnly</tt>. This feature can be used to bridge <tt>InOut</tt> requests to another queue so that a route on the other queue will send it&#180;s response directly back to the original <tt>JMSReplyTo</tt>. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>durableSubscriptionName</tt> </td><td colspan="1" r
 owspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> The durable subscriber name for specifying durable topic subscriptions. The <tt>clientId</tt> option <b>must</b> be configured as well. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>maxConcurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>1</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Specifies the maximum number of concurrent consumers. From Camel 2.11 onwards this option can also be used when doing request/reply over JMS. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>maxMessagesPerTask</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>-1</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> The number of messages per task. -1 is unlimited. If you use a range for concurrent consumers (eg min &lt; max), then this option can be used to set a value to eg <tt>100</tt> to
  control how fast the consumers will shrink when less work is required. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>preserveMessageQos</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Set to <tt>true</tt>, if you want to send message using the QoS settings specified on the message, instead of the QoS settings on the JMS endpoint. The following three headers are considered <tt>JMSPriority</tt>, <tt>JMSDeliveryMode</tt>, and <tt>JMSExpiration</tt>. You can provide all or only some of them. If not provided, Camel will fall back to use the values from the endpoint instead. So, when using this option, the headers override the values from the endpoint. The <tt>explicitQosEnabled</tt> option, by contrast, will only use options set on the endpoint, and not values from the message header. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>replyTo</tt> </td><td col
 span="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Provides an explicit ReplyTo destination, which overrides any incoming value of <tt>Message.getJMSReplyTo()</tt>. If you do <a shape="rect" href="request-reply.html" title="Request Reply">Request Reply</a> over JMS then <b>make sure</b> to read the section <em>Request-reply over JMS</em> further below for more details, and the <tt>replyToType</tt> option as well. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>replyToType</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.9:</b> Allows for explicitly specifying which kind of strategy to use for replyTo queues when doing request/reply over JMS. Possible values are: <tt>Temporary</tt>, <tt>Shared</tt>, or <tt>Exclusive</tt>. By default Camel will use temporary queues. However if <tt>replyTo</tt> has been confi
 gured, then <tt>Shared</tt> is used by default. This option allows you to use exclusive queues instead of shared ones. See further below for more details, and especially the notes about the implications if running in a clustered environment, and the fact that <tt>Shared</tt> reply queues has lower performance than its alternatives <tt>Temporary</tt> and <tt>Exclusive</tt>. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>requestTimeout</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>20000</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Producer only:</b> The timeout for waiting for a reply when using the InOut <a shape="rect" href="exchange-pattern.html" title="Exchange Pattern">Exchange Pattern</a> (in milliseconds). The default is 20 seconds. See below in section <em>About time to live</em> for more details. See also the <em>requestTimeoutCheckerInterval</em> option. </td></tr><tr><td colspan="1" rowspan="1" class="confluen
 ceTd"> <tt>selector</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Sets the JMS Selector, which is an SQL 92 predicate that is used to filter messages within the broker. You may have to encode special characters such as = as %3D <b>Before Camel 2.3.0</b>, we don't support this option in CamelConsumerTemplate </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>timeToLive</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>null</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> When sending messages, specifies the time-to-live of the message (in milliseconds). See below in section <em>About time to live</em> for more details. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>transacted</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Specifies whether to use tran
 sacted mode for sending/receiving messages using the InOnly <a shape="rect" href="exchange-pattern.html" title="Exchange Pattern">Exchange Pattern</a>. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>testConnectionOnStartup</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <tt>false</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.1:</b> Specifies whether to test the connection on startup. This ensures that when Camel starts that all the JMS consumers have a valid connection to the JMS broker. If a connection cannot be granted then Camel throws an exception on startup. This ensures that Camel is not started with failed connections. From <b>Camel 2.8</b> onwards also the JMS producers is tested as well. </td></tr></tbody></table>
 </div>
 
 
@@ -431,7 +431,7 @@ from(<span class="code-quote">"jms:SomeQ
 <p>Camel offers a number of options to configure request/reply over JMS that influence performance and clustered environments. The table below summaries the options.</p>
 
 <div class="confluenceTableSmall"><div class="table-wrap">
-<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"> Option </th><th colspan="1" rowspan="1" class="confluenceTh"> Performance </th><th colspan="1" rowspan="1" class="confluenceTh"> Cluster </th><th colspan="1" rowspan="1" class="confluenceTh"> Description </th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Temporary</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> A temporary queue is used as reply queue, and automatic created by Camel. To use this do <b>not</b> specify a replyTo queue name. And you can optionally configure <tt>replyToType=Temporary</tt> to make it stand out that temporary queues are in use. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Shared</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Slow </td><td colspan="1" rowspan="1" class="conflue
 nceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> A shared persistent queue is used as reply queue. The queue must be created beforehand, although some brokers can create them on the fly such as Apache ActiveMQ. To use this you must specify the replyTo queue name. And you can optionally configure <tt>replyToType=Shared</tt> to make it stand out that shared queues are in use. A shared queue can be used in a clustered environment with multiple nodes running this Camel application at the same time. All using the same shared reply queue. This is possible because JMS Message selectors are used to correlate expected reply messages; this impacts performance though. JMS Message selectors is slower, and therefore not as fast as <tt>Temporary</tt> or <tt>Exclusive</tt> queues. See further below how to tweak this for better performance. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Exclusive</tt> </td><td colspan="1" rowspan="1" class="confluenceT
 d"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> No </td><td colspan="1" rowspan="1" class="confluenceTd"> An exclusive persistent queue is used as reply queue. The queue must be created beforehand, although some brokers can create them on the fly such as Apache ActiveMQ. To use this you must specify the replyTo queue name. And you <b>must</b> configure <tt>replyToType=Exclusive</tt> to instruct Camel to use exclusive queues, as <tt>Shared</tt> is used by default, if a <tt>replyTo</tt> queue name was configured. When using exclusive reply queues, then JMS Message selectors are <b>not</b> in use, and therefore other applications must not use this queue as well. An exclusive queue <b>cannot</b> be used in a clustered environment with multiple nodes running this Camel application at the same time; as we do not have control if the reply queue comes back to the same node that sent the request message; that is why shared queues use JMS Message selectors to make sure
  of this. </td></tr></tbody></table>
+<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"> Option </th><th colspan="1" rowspan="1" class="confluenceTh"> Performance </th><th colspan="1" rowspan="1" class="confluenceTh"> Cluster </th><th colspan="1" rowspan="1" class="confluenceTh"> Description </th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Temporary</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> A temporary queue is used as reply queue, and automatic created by Camel. To use this do <b>not</b> specify a replyTo queue name. And you can optionally configure <tt>replyToType=Temporary</tt> to make it stand out that temporary queues are in use. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Shared</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Slow </td><td colspan="1" rowspan="1" class="conflue
 nceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> A shared persistent queue is used as reply queue. The queue must be created beforehand, although some brokers can create them on the fly such as Apache ActiveMQ. To use this you must specify the replyTo queue name. And you can optionally configure <tt>replyToType=Shared</tt> to make it stand out that shared queues are in use. A shared queue can be used in a clustered environment with multiple nodes running this Camel application at the same time. All using the same shared reply queue. This is possible because JMS Message selectors are used to correlate expected reply messages; this impacts performance though. JMS Message selectors is slower, and therefore not as fast as <tt>Temporary</tt> or <tt>Exclusive</tt> queues. See further below how to tweak this for better performance. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>Exclusive</tt> </td><td colspan="1" rowspan="1" class="confluenceT
 d"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> No </td><td colspan="1" rowspan="1" class="confluenceTd"> An exclusive persistent queue is used as reply queue. The queue must be created beforehand, although some brokers can create them on the fly such as Apache ActiveMQ. To use this you must specify the replyTo queue name. And you <b>must</b> configure <tt>replyToType=Exclusive</tt> to instruct Camel to use exclusive queues, as <tt>Shared</tt> is used by default, if a <tt>replyTo</tt> queue name was configured. When using exclusive reply queues, then JMS Message selectors are <b>not</b> in use, and therefore other applications must not use this queue as well. An exclusive queue <b>cannot</b> be used in a clustered environment with multiple nodes running this Camel application at the same time; as we do not have control if the reply queue comes back to the same node that sent the request message; that is why shared queues use JMS Message selectors to make sure
  of this. </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>concurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.11:</b> Allows to process reply messages concurrently using concurrent message listeners in use. You can specify a range using the <tt>concurrentConsumers</tt> and <tt>maxConcurrentConsumers</tt> options. <b>Notice:</b> That using <tt>Shared</tt> reply queues may not work as well with concurrent listeners, so use this option with care.</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"> <tt>maxConcurrentConsumers</tt> </td><td colspan="1" rowspan="1" class="confluenceTd"> Fast </td><td colspan="1" rowspan="1" class="confluenceTd"> Yes </td><td colspan="1" rowspan="1" class="confluenceTd"> <b>Camel 2.11:</b> Allows to process reply messages concurrently using concurrent message list
 eners in use. You can specify a range using the <tt>concurrentConsumers</tt> and <tt>maxConcurrentConsumers</tt> options. <b>Notice:</b> That using <tt>Shared</tt> reply queues may not work as well with concurrent listeners, so use this option with care. </td></tr></tbody></table>
 </div>
 </div>
 
@@ -453,6 +453,17 @@ from(xxx)
 
 <p>In this route we instruct Camel to route replies <a shape="rect" href="async.html" title="Async">asynchronously</a> using a thread pool with 5 threads.</p>
 
+<p>From Camel 2.11 onwards you can now configure the listener to use concurrent threads using the <tt>concurrentConsumers</tt> and <tt>maxConcurrentConsumers</tt> options. This allows you to easier configure this in Camel as shown below:</p>
+<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
+<pre class="code-java">
+from(xxx)
+.inOut().to(<span class="code-quote">"activemq:queue:foo?concurrentConsumers=5"</span>)
+.to(yyy)
+.to(zzz);
+</pre>
+</div></div>
+
+
 <h4><a shape="rect" name="JMS-RequestreplyoverJMSandusingasharedfixedreplyqueue"></a>Request-reply over JMS and using a shared fixed reply queue</h4>
 
 <p>If you use a fixed reply queue when doing <a shape="rect" href="request-reply.html" title="Request Reply">Request Reply</a> over JMS as shown in the example below, then pay attention.</p>