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Posted to commits@camel.apache.org by bu...@apache.org on 2015/05/10 13:20:11 UTC
svn commit: r950812 - in /websites/production/camel/content:
book-in-one-page.html book-pattern-appendix.html cache/main.pageCache
dead-letter-channel.html
Author: buildbot
Date: Sun May 10 11:20:11 2015
New Revision: 950812
Log:
Production update by buildbot for camel
Modified:
websites/production/camel/content/book-in-one-page.html
websites/production/camel/content/book-pattern-appendix.html
websites/production/camel/content/cache/main.pageCache
websites/production/camel/content/dead-letter-channel.html
Modified: websites/production/camel/content/book-in-one-page.html
==============================================================================
--- websites/production/camel/content/book-in-one-page.html (original)
+++ websites/production/camel/content/book-in-one-page.html Sun May 10 11:20:11 2015
@@ -4040,11 +4040,11 @@ While not actual tutorials you might fin
</div>
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<h2 id="BookInOnePage-Preface">Preface</h2><p>This tutorial aims to guide the reader through the stages of creating a project which uses Camel to facilitate the routing of messages from a JMS queue to a <a shape="rect" class="external-link" href="http://www.springramework.org" rel="nofollow">Spring</a> service. The route works in a synchronous fashion returning a response to the client.</p><p><style type="text/css">/*<![CDATA[*/
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<ul class="toc-indentation"><li><a shape="rect" href="#Tutorial-JmsRemoting-TutorialonSpringRemotingwithJMS">Tutorial on Spring Remoting with JMS</a></li><li><a shape="rect" href="#Tutorial-JmsRemoting-Preface">Preface</a></li><li><a shape="rect" href="#Tutorial-JmsRemoting-Prerequisites">Prerequisites</a></li><li><a shape="rect" href="#Tutorial-JmsRemoting-Distribution">Distribution</a></li><li><a shape="rect" href="#Tutorial-JmsRemoting-About">About</a></li><li><a shape="rect" href="#Tutorial-JmsRemoting-CreatetheCamelProject">Create the Camel Project</a>
<ul class="toc-indentation"><li><a shape="rect" href="#Tutorial-JmsRemoting-UpdatethePOMwithDependencies">Update the POM with Dependencies</a></li></ul>
</li><li><a shape="rect" href="#Tutorial-JmsRemoting-WritingtheServer">Writing the Server</a>
@@ -6230,11 +6230,11 @@ So we completed the last piece in the pi
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<ul class="toc-indentation"><li><a shape="rect" href="#Tutorial-AXIS-Camel-TutorialusingAxis1.4withApacheCamel">Tutorial using Axis 1.4 with Apache Camel</a>
<ul class="toc-indentation"><li><a shape="rect" href="#Tutorial-AXIS-Camel-Prerequisites">Prerequisites</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-Distribution">Distribution</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-Introduction">Introduction</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-SettinguptheprojecttorunAxis">Setting up the project to run Axis</a>
<ul class="toc-indentation"><li><a shape="rect" href="#Tutorial-AXIS-Camel-Maven2">Maven 2</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-wsdl">wsdl</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-ConfiguringAxis">Configuring Axis</a></li><li><a shape="rect" href="#Tutorial-AXIS-Camel-RunningtheExample">Running the Example</a></li></ul>
@@ -13018,7 +13018,7 @@ RouteBuilder builder = new RouteBuilder(
<p class="title">Difference between Dead Letter Channel and Default Error Handler</p>
<span class="aui-icon icon-success">Icon</span>
<div class="message-content">
- <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter channel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This
can be turned off by setting logNewException=false.</p>
+ <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>The Dead Letter Channel is also by default configured to not be verbose in the logs, so when a message is handled and moved to the dead letter endpoint, then there is nothing logged. If you want some level of logging you can use the various options on the redelivery policy / dead letter channel to configure this. For example if you want the message history then set logExhaustedMessageHistory=true (and logHandled=true for Camel 2.15.x or older).</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter cha
nnel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This can be turned off by setting logNewException=false.</p>
</div>
</div>
<h3 id="BookInOnePage-Redelivery">Redelivery</h3><p>It is common for a temporary outage or database deadlock to cause a message to fail to process; but the chances are if its tried a few more times with some time delay then it will complete fine. So we typically wish to use some kind of redelivery policy to decide how many times to try redeliver a message and how long to wait before redelivery attempts.</p><p>The <a shape="rect" class="external-link" href="http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/processor/RedeliveryPolicy.html">RedeliveryPolicy</a> defines how the message is to be redelivered. You can customize things like</p><ul><li>how many times a message is attempted to be redelivered before it is considered a failure and sent to the dead letter channel</li><li>the initial redelivery timeout</li><li>whether or not exponential backoff is used (i.e. the time between retries increases using a backoff multiplier)</li><li>whether to use collision avo
idance to add some randomness to the timings</li><li>delay pattern (see below for details)</li><li><strong>Camel 2.11:</strong> whether to allow redelivery during stopping/shutdown</li></ul><p>Once all attempts at redelivering the message fails then the message is forwarded to the dead letter queue.</p><h3 id="BookInOnePage-AboutmovingExchangetodeadletterqueueandusinghandled">About moving Exchange to dead letter queue and using handled</h3><p><strong>Handled</strong> on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a></p><p>When all attempts of redelivery have failed the <a shape="rect" href="exchange.html">Exchange</a> is moved to the dead letter queue (the dead letter endpoint). The exchange is then complete and from the client point of view it was processed. As such the <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> have handled the <a shape="rect" href="exchange.html">Exchange</a>.</p><p>For instance configuring the dead letter cha
nnel as:</p><p><strong>Using the <a shape="rect" href="fluent-builders.html">Fluent Builders</a></strong></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
@@ -13059,7 +13059,7 @@ RouteBuilder builder = new RouteBuilder(
<p>We also support for per <a shape="rect" href="exception-clause.html"><strong>onException</strong></a> to set a <strong>onRedeliver</strong>. That means you can do special on redelivery for different exceptions, as opposed to onRedelivery set on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> can be viewed as a global scope.</p>
</div>
</div>
-<h3 id="BookInOnePage-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re</strong> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the norma
l attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="BookInOnePage-RedeliverDelayPattern">Redeliver Delay Pattern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If used then the f
ollowing options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="alternate"><li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redelivery attempt
number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="BookInOnePage-Redeliveryheader">Redelivery header</h3><p>When a message is redelivered the <a shape="rect" class="external-link" href="http://camel.apache.org/maven/came
l-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also defined on the <code>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br clear="none"> In
Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="BookInOnePage-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<h3 id="BookInOnePage-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li><li>logExhaustedMessageHistory is true for default error handler, and false for dead letter channel.</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re</stron
g> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the normal attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="BookInOnePage-RedeliverDelayPattern">Redeliver Delay Patt
ern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If used then the following options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="alternate"><
li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redelivery attempt number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="BookInOnePage-Redeliveryheader">Redelivery header</h3><p>When a
message is redelivered the <a shape="rect" class="external-link" href="http://camel.apache.org/maven/camel-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also defined on the <co
de>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br clear="none"> In Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="BookInOnePage-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="theme: Default; brush: java; gutter: false" type="syntaxhighlighter"><![CDATA[String lastEndpointUri = exchange.getProperty(Exchange.TO_ENDPOINT, String.class);
]]></script>
</div></div><p>The <code>Exchange.TO_ENDPOINT</code> have the constant value <code>CamelToEndpoint</code>.</p><p>This information is updated when Camel sends a message to any endpoint. So if it exists its the <strong>last</strong> endpoint which Camel send the Exchange to.</p><p>When for example processing the <a shape="rect" href="exchange.html">Exchange</a> at a given <a shape="rect" href="endpoint.html">Endpoint</a> and the message is to be moved into the dead letter queue, then Camel also decorates the Exchange with another property that contains that <strong>last</strong> endpoint:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
@@ -18817,11 +18817,11 @@ template.send("direct:alias-verify&
</div>
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<p>The <strong>cxf:</strong> component provides integration with <a shape="rect" href="http://cxf.apache.org">Apache CXF</a> for connecting to JAX-WS services hosted in CXF.</p><p><style type="text/css">/*<![CDATA[*/
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<ul class="toc-indentation"><li><a shape="rect" href="#CXF-CXFComponent">CXF Component</a>
<ul class="toc-indentation"><li><a shape="rect" href="#CXF-URIformat">URI format</a></li><li><a shape="rect" href="#CXF-Options">Options</a>
<ul class="toc-indentation"><li><a shape="rect" href="#CXF-Thedescriptionsofthedataformats">The descriptions of the dataformats</a>
Modified: websites/production/camel/content/book-pattern-appendix.html
==============================================================================
--- websites/production/camel/content/book-pattern-appendix.html (original)
+++ websites/production/camel/content/book-pattern-appendix.html Sun May 10 11:20:11 2015
@@ -452,7 +452,7 @@ RouteBuilder builder = new RouteBuilder(
<p class="title">Difference between Dead Letter Channel and Default Error Handler</p>
<span class="aui-icon icon-success">Icon</span>
<div class="message-content">
- <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter channel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This
can be turned off by setting logNewException=false.</p>
+ <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>The Dead Letter Channel is also by default configured to not be verbose in the logs, so when a message is handled and moved to the dead letter endpoint, then there is nothing logged. If you want some level of logging you can use the various options on the redelivery policy / dead letter channel to configure this. For example if you want the message history then set logExhaustedMessageHistory=true (and logHandled=true for Camel 2.15.x or older).</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter cha
nnel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This can be turned off by setting logNewException=false.</p>
</div>
</div>
<h3 id="BookPatternAppendix-Redelivery">Redelivery</h3><p>It is common for a temporary outage or database deadlock to cause a message to fail to process; but the chances are if its tried a few more times with some time delay then it will complete fine. So we typically wish to use some kind of redelivery policy to decide how many times to try redeliver a message and how long to wait before redelivery attempts.</p><p>The <a shape="rect" class="external-link" href="http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/processor/RedeliveryPolicy.html">RedeliveryPolicy</a> defines how the message is to be redelivered. You can customize things like</p><ul><li>how many times a message is attempted to be redelivered before it is considered a failure and sent to the dead letter channel</li><li>the initial redelivery timeout</li><li>whether or not exponential backoff is used (i.e. the time between retries increases using a backoff multiplier)</li><li>whether to use collisi
on avoidance to add some randomness to the timings</li><li>delay pattern (see below for details)</li><li><strong>Camel 2.11:</strong> whether to allow redelivery during stopping/shutdown</li></ul><p>Once all attempts at redelivering the message fails then the message is forwarded to the dead letter queue.</p><h3 id="BookPatternAppendix-AboutmovingExchangetodeadletterqueueandusinghandled">About moving Exchange to dead letter queue and using handled</h3><p><strong>Handled</strong> on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a></p><p>When all attempts of redelivery have failed the <a shape="rect" href="exchange.html">Exchange</a> is moved to the dead letter queue (the dead letter endpoint). The exchange is then complete and from the client point of view it was processed. As such the <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> have handled the <a shape="rect" href="exchange.html">Exchange</a>.</p><p>For instance configuring the dea
d letter channel as:</p><p><strong>Using the <a shape="rect" href="fluent-builders.html">Fluent Builders</a></strong></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
@@ -493,7 +493,7 @@ RouteBuilder builder = new RouteBuilder(
<p>We also support for per <a shape="rect" href="exception-clause.html"><strong>onException</strong></a> to set a <strong>onRedeliver</strong>. That means you can do special on redelivery for different exceptions, as opposed to onRedelivery set on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> can be viewed as a global scope.</p>
</div>
</div>
-<h3 id="BookPatternAppendix-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re</strong> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the
normal attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="BookPatternAppendix-RedeliverDelayPattern">Redeliver Delay Pattern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If use
d then the following options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="alternate"><li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redeli
very attempt number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="BookPatternAppendix-Redeliveryheader">Redelivery header</h3><p>When a message is redelivered the <a shape="rect" class="external-link" href="http://camel.apa
che.org/maven/camel-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also defined on the <code>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br
clear="none"> In Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="BookPatternAppendix-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<h3 id="BookPatternAppendix-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li><li>logExhaustedMessageHistory is true for default error handler, and false for dead letter channel.</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re<
/strong> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the normal attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="BookPatternAppendix-RedeliverDelayPattern">Redelive
r Delay Pattern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If used then the following options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="
alternate"><li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redelivery attempt number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="BookPatternAppendix-Redeliveryheader">Redelivery hea
der</h3><p>When a message is redelivered the <a shape="rect" class="external-link" href="http://camel.apache.org/maven/camel-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also
defined on the <code>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br clear="none"> In Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="BookPatternAppendix-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="theme: Default; brush: java; gutter: false" type="syntaxhighlighter"><![CDATA[String lastEndpointUri = exchange.getProperty(Exchange.TO_ENDPOINT, String.class);
]]></script>
</div></div><p>The <code>Exchange.TO_ENDPOINT</code> have the constant value <code>CamelToEndpoint</code>.</p><p>This information is updated when Camel sends a message to any endpoint. So if it exists its the <strong>last</strong> endpoint which Camel send the Exchange to.</p><p>When for example processing the <a shape="rect" href="exchange.html">Exchange</a> at a given <a shape="rect" href="endpoint.html">Endpoint</a> and the message is to be moved into the dead letter queue, then Camel also decorates the Exchange with another property that contains that <strong>last</strong> endpoint:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
Modified: websites/production/camel/content/cache/main.pageCache
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Modified: websites/production/camel/content/dead-letter-channel.html
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--- websites/production/camel/content/dead-letter-channel.html (original)
+++ websites/production/camel/content/dead-letter-channel.html Sun May 10 11:20:11 2015
@@ -90,7 +90,7 @@
<p class="title">Difference between Dead Letter Channel and Default Error Handler</p>
<span class="aui-icon icon-success">Icon</span>
<div class="message-content">
- <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter channel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This
can be turned off by setting logNewException=false.</p>
+ <p>The Default Error Handler does very little: it ends the Exchange immediately and propagates the thrown Exception back to the caller.</p><p>The Dead Letter Channel lets you control behaviors including redelivery, whether to propagate the thrown Exception to the caller (the <strong>handled</strong> option), and where the (failed) Exchange should now be routed to.</p><p>The Dead Letter Channel is also by default configured to not be verbose in the logs, so when a message is handled and moved to the dead letter endpoint, then there is nothing logged. If you want some level of logging you can use the various options on the redelivery policy / dead letter channel to configure this. For example if you want the message history then set logExhaustedMessageHistory=true (and logHandled=true for Camel 2.15.x or older).</p><p>When the DeadLetterChannel moves a message to the dead letter endpoint, any new Exception thrown is by default handled by the dead letter cha
nnel as well. This ensures that the DeadLetterChannel will always succeed. From <strong>Camel 2.15</strong> onwards this behavior can be changed by setting the option deadLetterHandleNewException=false. Then if a new Exception is thrown, then the dead letter channel will fail and propagate back that new Exception (which is the behavior of the default error handler). When a new Exception occurs then the dead letter channel logs this at WARN level. This can be turned off by setting logNewException=false.</p>
</div>
</div>
<h3 id="DeadLetterChannel-Redelivery">Redelivery</h3><p>It is common for a temporary outage or database deadlock to cause a message to fail to process; but the chances are if its tried a few more times with some time delay then it will complete fine. So we typically wish to use some kind of redelivery policy to decide how many times to try redeliver a message and how long to wait before redelivery attempts.</p><p>The <a shape="rect" class="external-link" href="http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/processor/RedeliveryPolicy.html">RedeliveryPolicy</a> defines how the message is to be redelivered. You can customize things like</p><ul><li>how many times a message is attempted to be redelivered before it is considered a failure and sent to the dead letter channel</li><li>the initial redelivery timeout</li><li>whether or not exponential backoff is used (i.e. the time between retries increases using a backoff multiplier)</li><li>whether to use collision
avoidance to add some randomness to the timings</li><li>delay pattern (see below for details)</li><li><strong>Camel 2.11:</strong> whether to allow redelivery during stopping/shutdown</li></ul><p>Once all attempts at redelivering the message fails then the message is forwarded to the dead letter queue.</p><h3 id="DeadLetterChannel-AboutmovingExchangetodeadletterqueueandusinghandled">About moving Exchange to dead letter queue and using handled</h3><p><strong>Handled</strong> on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a></p><p>When all attempts of redelivery have failed the <a shape="rect" href="exchange.html">Exchange</a> is moved to the dead letter queue (the dead letter endpoint). The exchange is then complete and from the client point of view it was processed. As such the <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> have handled the <a shape="rect" href="exchange.html">Exchange</a>.</p><p>For instance configuring the dead le
tter channel as:</p><p><strong>Using the <a shape="rect" href="fluent-builders.html">Fluent Builders</a></strong></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
@@ -131,7 +131,7 @@
<p>We also support for per <a shape="rect" href="exception-clause.html"><strong>onException</strong></a> to set a <strong>onRedeliver</strong>. That means you can do special on redelivery for different exceptions, as opposed to onRedelivery set on <a shape="rect" href="dead-letter-channel.html">Dead Letter Channel</a> can be viewed as a global scope.</p>
</div>
</div>
-<h3 id="DeadLetterChannel-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re</strong> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the n
ormal attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="DeadLetterChannel-RedeliverDelayPattern">Redeliver Delay Pattern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If used th
en the following options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="alternate"><li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redelivery
attempt number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="DeadLetterChannel-Redeliveryheader">Redelivery header</h3><p>When a message is redelivered the <a shape="rect" class="external-link" href="http://camel.apache.or
g/maven/camel-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also defined on the <code>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br clear
="none"> In Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="DeadLetterChannel-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<h3 id="DeadLetterChannel-Redeliverydefaultvalues">Redelivery default values</h3><p>Redelivery is disabled by default.</p><p>The default redeliver policy will use the following values:</p><ul><li>maximumRedeliveries=0</li><li>redeliverDelay=1000L (1 second)</li><li>maximumRedeliveryDelay = 60 * 1000L (60 seconds)</li><li>And the exponential backoff and collision avoidance is turned off.</li><li>The retriesExhaustedLogLevel are set to LoggingLevel.ERROR</li><li>The retryAttemptedLogLevel are set to LoggingLevel.DEBUG</li><li>Stack traces is logged for exhausted messages from Camel 2.2 onwards.</li><li>Handled exceptions is not logged from Camel 2.3 onwards</li><li>logExhaustedMessageHistory is true for default error handler, and false for dead letter channel.</li></ul><p>The maximum redeliver delay ensures that a delay is never longer than the value, default 1 minute. This can happen if you turn on the exponential backoff.</p><p>The maximum redeliveries is the number of <strong>re</s
trong> delivery attempts. By default Camel will try to process the exchange 1 + 5 times. 1 time for the normal attempt and then 5 attempts as redeliveries.<br clear="none"> Setting the maximumRedeliveries to a negative value such as -1 will then always redelivery (unlimited).<br clear="none"> Setting the maximumRedeliveries to 0 will disable any re delivery attempt.</p><p>Camel will log delivery failures at the DEBUG logging level by default. You can change this by specifying retriesExhaustedLogLevel and/or retryAttemptedLogLevel. See <a shape="rect" class="external-link" href="http://svn.apache.org/repos/asf/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ExceptionBuilderWithRetryLoggingLevelSetTest.java">ExceptionBuilderWithRetryLoggingLevelSetTest</a> for an example.</p><p>You can turn logging of stack traces on/off. If turned off Camel will still log the redelivery attempt. Its just much less verbose.</p><h4 id="DeadLetterChannel-RedeliverDelayPattern">Redeliver De
lay Pattern</h4><p>Delay pattern is used as a single option to set a range pattern for delays. If used then the following options does not apply: (delay, backOffMultiplier, useExponentialBackOff, useCollisionAvoidance, maximumRedeliveryDelay).</p><p>The idea is to set groups of ranges using the following syntax: <code>limit:delay;limit 2:delay 2;limit 3:delay 3;...;limit N:delay N</code></p><p>Each group has two values separated with colon</p><ul class="alternate"><li>limit = upper limit</li><li>delay = delay in millis<br clear="none"> And the groups is again separated with semi colon.<br clear="none"> The rule of thumb is that the next groups should have a higher limit than the previous group.</li></ul><p>Lets clarify this with an example:<br clear="none"> <code>delayPattern=5:1000;10:5000;20:20000</code></p><p>That gives us 3 groups:</p><ul class="alternate"><li>5:1000</li><li>10:5000</li><li>20:20000</li></ul><p>Resulting in these delays for redelivery attempt:</p><ul class="alte
rnate"><li>Redelivery attempt number 1..4 = 0 millis (as the first group start with 5)</li><li>Redelivery attempt number 5..9 = 1000 millis (the first group)</li><li>Redelivery attempt number 10..19 = 5000 millis (the second group)</li><li>Redelivery attempt number 20.. = 20000 millis (the last group)</li></ul><p>Note: The first redelivery attempt is 1, so the first group should start with 1 or higher.</p><p>You can start a group with limit 1 to eg have a starting delay: <code>delayPattern=1:1000;5:5000</code></p><ul class="alternate"><li>Redelivery attempt number 1..4 = 1000 millis (the first group)</li><li>Redelivery attempt number 5.. = 5000 millis (the last group)</li></ul><p>There is no requirement that the next delay should be higher than the previous. You can use any delay value you like. For example with <code>delayPattern=1:5000;3:1000</code> we start with 5 sec delay and then later reduce that to 1 second.</p><h3 id="DeadLetterChannel-Redeliveryheader">Redelivery header</h
3><p>When a message is redelivered the <a shape="rect" class="external-link" href="http://camel.apache.org/maven/camel-core/apidocs/org/apache/camel/processor/DeadLetterChannel.html">DeadLetterChannel</a> will append a customizable header to the message to indicate how many times its been redelivered. <br clear="none"> Before Camel 2.6: The header is <strong>CamelRedeliveryCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_COUNTER</code>.<br clear="none"> Starting with 2.6: The header <strong>CamelRedeliveryMaxCounter</strong>, which is also defined on the <code>Exchange.REDELIVERY_MAX_COUNTER</code>, contains the maximum redelivery setting. This header is absent if you use <code>retryWhile</code> or have unlimited maximum redelivery configured.</p><p>And a boolean flag whether it is being redelivered or not (first attempt)<br clear="none"> The header <strong>CamelRedelivered</strong> contains a boolean if the message is redelivered or not, which is also define
d on the <code>Exchange.REDELIVERED</code>.</p><p>Dynamically calculated delay from the exchange<br clear="none"> In Camel 2.9 and 2.8.2: The header is <strong>CamelRedeliveryDelay</strong>, which is also defined on the <code>Exchange.REDELIVERY_DELAY</code>.<br clear="none"> Is this header is absent, normal redelivery rules apply.</p><h4 id="DeadLetterChannel-Whichendpointfailed">Which endpoint failed</h4><p><strong>Available as of Camel 2.1</strong></p><p>When Camel routes messages it will decorate the <a shape="rect" href="exchange.html">Exchange</a> with a property that contains the <strong>last</strong> endpoint Camel send the <a shape="rect" href="exchange.html">Exchange</a> to:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="theme: Default; brush: java; gutter: false" type="syntaxhighlighter"><![CDATA[String lastEndpointUri = exchange.getProperty(Exchange.TO_ENDPOINT, String.class);
]]></script>
</div></div><p>The <code>Exchange.TO_ENDPOINT</code> have the constant value <code>CamelToEndpoint</code>.</p><p>This information is updated when Camel sends a message to any endpoint. So if it exists its the <strong>last</strong> endpoint which Camel send the Exchange to.</p><p>When for example processing the <a shape="rect" href="exchange.html">Exchange</a> at a given <a shape="rect" href="endpoint.html">Endpoint</a> and the message is to be moved into the dead letter queue, then Camel also decorates the Exchange with another property that contains that <strong>last</strong> endpoint:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">