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Posted to commits@camel.apache.org by bu...@apache.org on 2017/08/25 08:22:03 UTC
svn commit: r1017260 [34/40] - in /websites/production/camel/content: ./
cache/
Modified: websites/production/camel/content/tracer-example.html
==============================================================================
--- websites/production/camel/content/tracer-example.html (original)
+++ websites/production/camel/content/tracer-example.html Fri Aug 25 08:22:01 2017
@@ -36,18 +36,6 @@
<![endif]-->
- <link href='//camel.apache.org/styles/highlighter/styles/shCoreCamel.css' rel='stylesheet' type='text/css' />
- <link href='//camel.apache.org/styles/highlighter/styles/shThemeCamel.css' rel='stylesheet' type='text/css' />
- <script src='//camel.apache.org/styles/highlighter/scripts/shCore.js' type='text/javascript'></script>
- <script src='//camel.apache.org/styles/highlighter/scripts/shBrushSql.js' type='text/javascript'></script>
- <script src='//camel.apache.org/styles/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
- <script src='//camel.apache.org/styles/highlighter/scripts/shBrushXml.js' type='text/javascript'></script>
- <script src='//camel.apache.org/styles/highlighter/scripts/shBrushPlain.js' type='text/javascript'></script>
-
- <script type="text/javascript">
- SyntaxHighlighter.defaults['toolbar'] = false;
- SyntaxHighlighter.all();
- </script>
<title>
Apache Camel: Tracer Example
@@ -87,106 +75,10 @@
<tbody>
<tr>
<td valign="top" width="100%">
-<div class="wiki-content maincontent"><h2 id="TracerExample-TracerExample">Tracer Example</h2><h3 id="TracerExample-Introduction">Introduction</h3><p>This example demonstrates the <a shape="rect" href="tracer.html">Tracer</a>. <a shape="rect" href="tracer.html">Tracer</a> is a tracing feature build in camel core to log snapshots of <a shape="rect" href="exchange.html">Exchange</a>s while they are routed. This allows you to see:</p><ul class="alternate"><li>how a given <a shape="rect" href="exchange.html">Exchange</a> was routed</li><li>a snapshot of the content of the <a shape="rect" href="exchange.html">Exchange</a> at any given node it passed in the route</li></ul><p>When used Camel will by default log the snapshot at <strong><code>INFO</code></strong> level. This example demonstrates how to persist trace snapshots using <a shape="rect" href="jpa.html">JPA</a> into a database. This allows you to store this information and query them from a SQL prompt, giving you full power to
analyze the data.</p><h3 id="TracerExample-Requirements">Requirements</h3><p>This requires Camel 2.0, the <strong><code>camel-jpa</code></strong> component and configuration of the target database.</p><h3 id="TracerExample-DataModel">Data Model</h3><p>Camel uses the <strong><code>org.apache.camel.processor.interceptor.JpaTraceEventMessage</code></strong> JPA @Entity as data model. This class has been enhanced with <a shape="rect" href="jpa.html">JPA</a> annotations.</p><p>The class has the following properties in the <a shape="rect" href="jpa.html">JPA</a> model:</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Property</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Body</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>S
tring</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> body dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>BodyType</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> body java type such as <strong><code>String</code></strong>, <strong><code>org.w3c.Document</code></strong>, <strong><code>com.mycompany.MyOrder</code></strong> etc.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CausedByException</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Ex
change</a> exception (if any) dumped as a String including stacktrace.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ExchangeId</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Unique id of the <a shape="rect" href="exchange.html">Exchange.</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ExchangePattern</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange-pattern.html">Exchange Pattern</a> such as <strong><code>InOnly</code></strong> or <strong><code>InOut</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>FromEndpoint</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenc
eTd"><p>the URI of the starting consumer the <a shape="rect" href="exchange.html">Exchange</a> was created (usually a from in the route).</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Headers</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> headers dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Id</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Long</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Primary key that is generated by the database.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutBody</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" cla
ss="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</code></strong> body (if any) dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutBodyType</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</code></strong> body (if any) java type such as <strong><code>String</code></strong>, <strong><code>org.w3c.Document</code></strong>, <strong><code>com.mycompany.MyOrder</code></strong> etc.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutHeaders</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</c
ode></strong> (if any) headers dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>PreviousNode</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the previous step in the route. Is <strong><code>null</code></strong> if there wasn't a previous node such as the start.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Properties</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> properties dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ShortExchangeId</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code
></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the <a shape="rect" href="exchange.html">Exchange</a> without the machine name.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Timestamp</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Date</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Timestamp when the snapshot was generated. Is the system time of the JMV in which Camel is running.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ToNode</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the next step in the route.</p></td></tr></tbody></table></div><p>The table name for persisting trace events is: <strong><code>CAMEL_MESSAGETRACED</code></strong></p><h3 id="TracerExample-Configurationofthedatabase">Configur
ation of the database</h3><p>The <a shape="rect" href="tracer.html">Tracer</a> uses standard <a shape="rect" href="jpa.html">JPA</a> configuration for setting the database. In the <strong><code>META-INF/persistence.xml</code></strong> file we setup the service unit and the database configuration as:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
-<persistence xmlns="http://java.sun.com/xml/ns/persistence"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
- version="1.0">
-
- <persistence-unit name="tracer" transaction-type="RESOURCE_LOCAL">
- <class>org.apache.camel.processor.interceptor.jpa.JpaTraceEventMessage</class>
-
- <properties>
- <property name="hibernate.dialect" value="org.apache.camel.example.tracer.FixedDerbyDialect"/>
- <property name="hibernate.connection.driver_class" value="org.apache.derby.jdbc.EmbeddedDriver"/>
- <property name="hibernate.connection.url" value="jdbc:derby:target/derby;create=true"/>
- <property name="hibernate.hbm2ddl.auto" value="create"/>
-
- <!-- debugging flags -->
- <!-- <property name="hibernate.show_sql" value="true"/>
- <property name="hibernate.format_sql" value="true"/> -->
- </properties>
-
- </persistence-unit>
-</persistence>
-]]></script>
-</div></div>What is important is to add the <strong><code>JpaTraceEventMessage</code></strong> as a class in the <strong><code>persistence.xml</code></strong> file to register our data model:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[<class>org.apache.camel.processor.interceptor.JpaTraceEventMessage</class>
-]]></script>
-</div></div><p>In this example we use Hibernate JPA and a HSQLDB as database.</p><h3 id="TracerExample-RunningtheExample">Running the Example</h3><p>The <strong><code>README.txt</code></strong> states how to run the example from either ANT or Maven.</p><p>Here we show running with Maven:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: java; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[mvn camel:run
-]]></script>
-</div></div><p>When the application starts it start:</p><ul class="alternate"><li>in the console</li><li>a GUI for browsing the SQL database</li></ul><p>Select the console where the application should prompt you to enter some words. Try entering: <strong><code>Camel</code></strong>. The application should respond with a text quote.</p><p>You can also enter multiple quotes separate with space, and the response should be the best quote based on the list of words given. See the file <strong><code>src/main/resources/META-INF/spring/camel-context.xml</code></strong> to give you an idea how it works.</p><p>You can enter: <strong><code>Camel Beer</code></strong> and it should be smart enough to find a quote for the beer <img class="emoticon emoticon-wink" src="https://cwiki.apache.org/confluence/s/en_GB/5997/6f42626d00e36f53fe51440403446ca61552e2a2.1/_/images/icons/emoticons/wink.png" data-emoticon-name="wink" alt="(wink)"></p><h3 id="TracerExample-SeeingtheTraceEvents">Seeing the Trace Ev
ents</h3><p>When the program was started a GUI application was started as well. Its a SQL prompt for the database. So try entering:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: sql; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[select * from camel_messagetraced
-]]></script>
-</div></div><p>And it should return the list of trace events in the SQL.</p><p>We enter this SQL:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: sql; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[select id, shortExchangeId, previousNode, toNode, body from camel_messagetraced]]></script>
-</div></div><p>and get the output as the picture below:</p><p><br clear="none"> <span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image" src="tracer-example.data/tracer_sql.png" data-image-src="/confluence/download/attachments/107823/tracer_sql.png?version=1&modificationDate=1232323775000&api=v2" data-unresolved-comment-count="0" data-linked-resource-id="9605" data-linked-resource-version="1" data-linked-resource-type="attachment" data-linked-resource-default-alias="tracer_sql.png" data-base-url="https://cwiki.apache.org/confluence" data-linked-resource-content-type="image/png" data-linked-resource-container-id="107823" data-linked-resource-container-version="26"></span></p><h3 id="TracerExample-Routing">Routing</h3><p>The diagram below illustrates the route diagram generated using <a shape="rect" href="visualisation.html">Visualisation</a>.<br clear="none"> <span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image" src
="tracer-example.data/tracer_dot.png" data-image-src="/confluence/download/attachments/107823/tracer_dot.png?version=1&modificationDate=1232326207000&api=v2" data-unresolved-comment-count="0" data-linked-resource-id="9606" data-linked-resource-version="1" data-linked-resource-type="attachment" data-linked-resource-default-alias="tracer_dot.png" data-base-url="https://cwiki.apache.org/confluence" data-linked-resource-content-type="image/png" data-linked-resource-container-id="107823" data-linked-resource-container-version="26"></span></p><p>We receive an Exchange from the in stream, then its split using the <strong><code>splitWords</code></strong> method. Then the quote method is invoked before it's aggregated and finally sent to the stream out to be printed in the console.</p><h3 id="TracerExample-TracetheRouting">Trace the Routing</h3><p>If we look at the 6 rows from the traced SQL (the first picture) and with the route diagram in mind we can get a better understand how the
<a shape="rect" href="exchange.html">Exchange</a> was routed.</p><ol><li>The <a shape="rect" href="exchange.html">Exchange</a> does not have a previousNode so its the first step where its consumed from the input stream and that its going to the splitter.</li><li>The exchange id has changed and this is the output of the splitter as it creates a new Exchange. We can also see this one has one word in the body. This <a shape="rect" href="exchange.html">Exchange</a> is being routed to the quote bean next.</li><li>This is the 2nd output from the splitter containing the 2nd word. This <a shape="rect" href="exchange.html">Exchange</a> is being routed to the quote bean next.</li><li>This is the Beer <a shape="rect" href="exchange.html">Exchange</a> where we can see the output from the quote server and that its being routed to the aggregator.</li><li>This is the Camel <a shape="rect" href="exchange.html">Exchange</a> where we can see the output from the quote server and that its being routed
to the aggregator.</li><li>This is the result of the aggregator where the <a shape="rect" href="exchange.html">Exchange</a> ending with id <strong><code>0-2</code></strong> "was the winner" and is being routed as the aggregated result to the stream out.</li></ol><h3 id="TracerExample-ConfigurationofTracinginCamel">Configuration of <a shape="rect" href="jpa.html">JPA</a> Tracing in Camel</h3><p>In Camel you need to configure it to use JPA for tracing. We do this as by adding a tracer in the <strong><code>META-INF/camel-context.mxl</code></strong> file:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
-<!-- use camel jpa trace so we can see all the traced exchanges in a database -->
-<bean id="camelTracer" class="org.apache.camel.processor.interceptor.Tracer">
- <!-- turn on jpa tracing, otherwise the TraceEventMessage is a non JPA Entity class -->
- <property name="useJpa" value="true"/>
- <!-- the destination to send the traced messages -->
- <property name="destination" ref="traced"/>
- <!-- we turn ordinary trace logging off so we only see the traced messages in the database,
- but you can have both if you like -->
- <property name="logLevel" value="OFF"/>
-</bean>
-]]></script>
-</div></div>To properly configure <a shape="rect" href="jpa.html">JPA</a> for tracing we must complete these two steps:<ol><li>Enable the <a shape="rect" href="jpa.html">JPA</a> tracing by setting the property <strong><code>useJpa=true</code></strong>.</li><li>Set the destination or <strong><code>destinationUri</code></strong> to a <a shape="rect" href="jpa.html">JPA</a> producer endpoint.</li></ol><p>In this example we set the destintation to refer to an endpoint defined in the camel context:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
-<endpoint id="traced" uri="jpa://org.apache.camel.processor.interceptor.JpaTraceEventMessage?persistenceUnit=tracer"/>
-]]></script>
-</div></div>Here it's important that the endpoint is configure with the <strong><code>org.apache.camel.processor.interceptor.JpaTraceEventMessage</code></strong> as entity name and the <strong><code>persistenceUnit</code></strong> as an option. In out example we use tracer.<p>Then the following is standard Spring <a shape="rect" href="jpa.html">JPA</a> configuration:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
-<!-- this is ordinary JPA spring configuration -->
-<bean id="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate">
- <property name="transactionManager">
- <bean class="org.springframework.orm.jpa.JpaTransactionManager">
- <property name="entityManagerFactory" ref="entityManagerFactory"/>
- </bean>
- </property>
-</bean>
-
-<!-- this is ordinary JPA spring configuration -->
-<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
- <!-- we have named our presistence unit tracer in the META-INF/persistence.xml file -->
- <property name="persistenceUnitName" value="tracer"/>
-</bean>
-]]></script>
-</div></div>However we must set the <strong><code>persistenceUnitName</code></strong> to the same unit name we defined in <strong><code>persistence.xml</code></strong>, such as <strong><code>tracer</code></strong> as we are using in this example.<p>And if you are wondering how the Camel route is defined then its here:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
-<route>
- <!-- in stream to allow you to enter some text in the console -->
- <from uri="stream:in?initialPromptDelay=4000&amp;promptDelay=2000&amp;promptMessage=Enter some words:"/>
-
- <!-- split the text -->
- <split>
- <!-- use methodCall expression to split the words, using a java bean to do it -->
- <method bean="quoteService" method="splitWords"/>
-
- <!-- for each split message invoke the quote server to get a quote of the word -->
- <to uri="bean:quoteService?method=quote"/>
-
- <!-- now we need to find the best quote, so we aggregate all the splitted words
- we use our own strategy how to aggregate -->
- <aggregate strategyRef="myAggregateStrategy">
- <!-- correlate everything using constant true, as they are all from the same source -->
- <correlationExpression>
- <constant>true</constant>
- </correlationExpression>
- <!-- complete after 1 sec on inactivity -->
- <completionTimeout>
- <constant>1000</constant>
- </completionTimeout>
- <!-- send the result to stream out so we can see the response in the console -->
- <to uri="stream:out"/>
- </aggregate>
- </split>
-</route>
-]]></script>
-</div></div><h3 id="TracerExample-Seealso">See also</h3><ul class="alternate"><li><a shape="rect" href="tracer.html">Tracer</a></li><li><a shape="rect" href="examples.html">Examples</a></li><li><a shape="rect" href="tutorials.html">Tutorials</a></li><li><a shape="rect" href="user-guide.html">User Guide</a></li></ul></div>
+<div class="wiki-content maincontent"><h2 id="TracerExample-TracerExample">Tracer Example</h2><h3 id="TracerExample-Introduction">Introduction</h3><p>This example demonstrates the <a shape="rect" href="tracer.html">Tracer</a>. <a shape="rect" href="tracer.html">Tracer</a> is a tracing feature build in camel core to log snapshots of <a shape="rect" href="exchange.html">Exchange</a>s while they are routed. This allows you to see:</p><ul class="alternate"><li>how a given <a shape="rect" href="exchange.html">Exchange</a> was routed</li><li>a snapshot of the content of the <a shape="rect" href="exchange.html">Exchange</a> at any given node it passed in the route</li></ul><p>When used Camel will by default log the snapshot at <strong><code>INFO</code></strong> level. This example demonstrates how to persist trace snapshots using <a shape="rect" href="jpa.html">JPA</a> into a database. This allows you to store this information and query them from a SQL prompt, giving you full power to
analyze the data.</p><h3 id="TracerExample-Requirements">Requirements</h3><p>This requires Camel 2.0, the <strong><code>camel-jpa</code></strong> component and configuration of the target database.</p><h3 id="TracerExample-DataModel">Data Model</h3><p>Camel uses the <strong><code>org.apache.camel.processor.interceptor.JpaTraceEventMessage</code></strong> JPA @Entity as data model. This class has been enhanced with <a shape="rect" href="jpa.html">JPA</a> annotations.</p><p>The class has the following properties in the <a shape="rect" href="jpa.html">JPA</a> model:</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Property</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Body</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>S
tring</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> body dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>BodyType</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> body java type such as <strong><code>String</code></strong>, <strong><code>org.w3c.Document</code></strong>, <strong><code>com.mycompany.MyOrder</code></strong> etc.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CausedByException</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Ex
change</a> exception (if any) dumped as a String including stacktrace.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ExchangeId</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Unique id of the <a shape="rect" href="exchange.html">Exchange.</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ExchangePattern</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange-pattern.html">Exchange Pattern</a> such as <strong><code>InOnly</code></strong> or <strong><code>InOut</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>FromEndpoint</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenc
eTd"><p>the URI of the starting consumer the <a shape="rect" href="exchange.html">Exchange</a> was created (usually a from in the route).</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Headers</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>IN</code></strong> headers dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Id</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Long</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Primary key that is generated by the database.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutBody</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" cla
ss="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</code></strong> body (if any) dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutBodyType</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</code></strong> body (if any) java type such as <strong><code>String</code></strong>, <strong><code>org.w3c.Document</code></strong>, <strong><code>com.mycompany.MyOrder</code></strong> etc.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>OutHeaders</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> <strong><code>OUT</c
ode></strong> (if any) headers dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>PreviousNode</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the previous step in the route. Is <strong><code>null</code></strong> if there wasn't a previous node such as the start.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Properties</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The <a shape="rect" href="exchange.html">Exchange</a> properties dumped as a <strong><code>String</code></strong>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ShortExchangeId</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code
></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the <a shape="rect" href="exchange.html">Exchange</a> without the machine name.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Timestamp</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>Date</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Timestamp when the snapshot was generated. Is the system time of the JMV in which Camel is running.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>ToNode</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>String</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong><code>id</code></strong> of the next step in the route.</p></td></tr></tbody></table></div><p>The table name for persisting trace events is: <strong><code>CAMEL_MESSAGETRACED</code></strong></p><h3 id="TracerExample-Configurationofthedatabase">Configur
ation of the database</h3><p>The <a shape="rect" href="tracer.html">Tracer</a> uses standard <a shape="rect" href="jpa.html">JPA</a> configuration for setting the database. In the <strong><code>META-INF/persistence.xml</code></strong> file we setup the service unit and the database configuration as:<plain-text-body>{snippet:id=e1|lang=xml|url=camel/trunk/examples/camel-example-tracer/src/main/resources/META-INF/persistence.xml}</plain-text-body>What is important is to add the <strong><code>JpaTraceEventMessage</code></strong> as a class in the <strong><code>persistence.xml</code></strong> file to register our data model:</p><parameter ac:name="">xml</parameter><plain-text-body><class>org.apache.camel.processor.interceptor.JpaTraceEventMessage</class>
+</plain-text-body><p>In this example we use Hibernate JPA and a HSQLDB as database.</p><h3 id="TracerExample-RunningtheExample">Running the Example</h3><p>The <strong><code>README.txt</code></strong> states how to run the example from either ANT or Maven.</p><p>Here we show running with Maven:</p><plain-text-body>mvn camel:run
+</plain-text-body><p>When the application starts it start:</p><ul class="alternate"><li>in the console</li><li>a GUI for browsing the SQL database</li></ul><p>Select the console where the application should prompt you to enter some words. Try entering: <strong><code>Camel</code></strong>. The application should respond with a text quote.</p><p>You can also enter multiple quotes separate with space, and the response should be the best quote based on the list of words given. See the file <strong><code>src/main/resources/META-INF/spring/camel-context.xml</code></strong> to give you an idea how it works.</p><p>You can enter: <strong><code>Camel Beer</code></strong> and it should be smart enough to find a quote for the beer <img class="emoticon emoticon-wink" src="https://cwiki.apache.org/confluence/s/en_GB/5997/6f42626d00e36f53fe51440403446ca61552e2a2.1/_/images/icons/emoticons/wink.png" data-emoticon-name="wink" alt="(wink)"></p><h3 id="TracerExample-SeeingtheTraceEvents">Seeing the Tr
ace Events</h3><p>When the program was started a GUI application was started as well. Its a SQL prompt for the database. So try entering:</p><parameter ac:name="language">sql</parameter><plain-text-body>select * from camel_messagetraced
+</plain-text-body><p>And it should return the list of trace events in the SQL.</p><p>We enter this SQL:</p><parameter ac:name="language">sql</parameter><plain-text-body>select id, shortExchangeId, previousNode, toNode, body from camel_messagetraced</plain-text-body><p>and get the output as the picture below:</p><p><br clear="none"> <span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image" src="tracer-example.data/tracer_sql.png" data-image-src="/confluence/download/attachments/107823/tracer_sql.png?version=1&modificationDate=1232323775000&api=v2" data-unresolved-comment-count="0" data-linked-resource-id="9605" data-linked-resource-version="1" data-linked-resource-type="attachment" data-linked-resource-default-alias="tracer_sql.png" data-base-url="https://cwiki.apache.org/confluence" data-linked-resource-content-type="image/png" data-linked-resource-container-id="107823" data-linked-resource-container-version="27"></span></p><h3 id="TracerExample-R
outing">Routing</h3><p>The diagram below illustrates the route diagram generated using <a shape="rect" href="visualisation.html">Visualisation</a>.<br clear="none"> <span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image" src="tracer-example.data/tracer_dot.png" data-image-src="/confluence/download/attachments/107823/tracer_dot.png?version=1&modificationDate=1232326207000&api=v2" data-unresolved-comment-count="0" data-linked-resource-id="9606" data-linked-resource-version="1" data-linked-resource-type="attachment" data-linked-resource-default-alias="tracer_dot.png" data-base-url="https://cwiki.apache.org/confluence" data-linked-resource-content-type="image/png" data-linked-resource-container-id="107823" data-linked-resource-container-version="27"></span></p><p>We receive an Exchange from the in stream, then its split using the <strong><code>splitWords</code></strong> method. Then the quote method is invoked before it's aggregated and finally sent
to the stream out to be printed in the console.</p><h3 id="TracerExample-TracetheRouting">Trace the Routing</h3><p>If we look at the 6 rows from the traced SQL (the first picture) and with the route diagram in mind we can get a better understand how the <a shape="rect" href="exchange.html">Exchange</a> was routed.</p><ol><li>The <a shape="rect" href="exchange.html">Exchange</a> does not have a previousNode so its the first step where its consumed from the input stream and that its going to the splitter.</li><li>The exchange id has changed and this is the output of the splitter as it creates a new Exchange. We can also see this one has one word in the body. This <a shape="rect" href="exchange.html">Exchange</a> is being routed to the quote bean next.</li><li>This is the 2nd output from the splitter containing the 2nd word. This <a shape="rect" href="exchange.html">Exchange</a> is being routed to the quote bean next.</li><li>This is the Beer <a shape="rect" href="exchange.html">Excha
nge</a> where we can see the output from the quote server and that its being routed to the aggregator.</li><li>This is the Camel <a shape="rect" href="exchange.html">Exchange</a> where we can see the output from the quote server and that its being routed to the aggregator.</li><li>This is the result of the aggregator where the <a shape="rect" href="exchange.html">Exchange</a> ending with id <strong><code>0-2</code></strong> "was the winner" and is being routed as the aggregated result to the stream out.</li></ol><h3 id="TracerExample-ConfigurationofTracinginCamel">Configuration of <a shape="rect" href="jpa.html">JPA</a> Tracing in Camel</h3><p>In Camel you need to configure it to use JPA for tracing. We do this as by adding a tracer in the <strong><code>META-INF/camel-context.mxl</code></strong> file:<plain-text-body>{snippet:id=e1|lang=xml|url=camel/trunk/examples/camel-example-tracer/src/main/resources/META-INF/spring/camel-context.xml}</plain-text-body>To properly configure
<a shape="rect" href="jpa.html">JPA</a> for tracing we must complete these two steps:</p><ol><li>Enable the <a shape="rect" href="jpa.html">JPA</a> tracing by setting the property <strong><code>useJpa=true</code></strong>.</li><li>Set the destination or <strong><code>destinationUri</code></strong> to a <a shape="rect" href="jpa.html">JPA</a> producer endpoint.</li></ol><p>In this example we set the destintation to refer to an endpoint defined in the camel context:<plain-text-body>{snippet:id=e3|lang=xml|url=camel/trunk/examples/camel-example-tracer/src/main/resources/META-INF/spring/camel-context.xml}</plain-text-body>Here it's important that the endpoint is configure with the <strong><code>org.apache.camel.processor.interceptor.JpaTraceEventMessage</code></strong> as entity name and the <strong><code>persistenceUnit</code></strong> as an option. In out example we use tracer.</p><p>Then the following is standard Spring <a shape="rect" href="jpa.html">JPA</a> configura
tion:<plain-text-body>{snippet:id=e2|lang=xml|url=camel/trunk/examples/camel-example-tracer/src/main/resources/META-INF/spring/camel-context.xml}</plain-text-body>However we must set the <strong><code>persistenceUnitName</code></strong> to the same unit name we defined in <strong><code>persistence.xml</code></strong>, such as <strong><code>tracer</code></strong> as we are using in this example.</p><p>And if you are wondering how the Camel route is defined then its here:<plain-text-body>{snippet:id=e4|lang=xml|url=camel/trunk/examples/camel-example-tracer/src/main/resources/META-INF/spring/camel-context.xml}</plain-text-body></p><h3 id="TracerExample-Seealso">See also</h3><ul class="alternate"><li><a shape="rect" href="tracer.html">Tracer</a></li><li><a shape="rect" href="examples.html">Examples</a></li><li><a shape="rect" href="tutorials.html">Tutorials</a></li><li><a shape="rect" href="user-guide.html">User Guide</a></li></ul></div>
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