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The xslt: component allows you to process a message using an XSLT template. This can be ideal when using Templating to generate respopnses for requests.

URI format

Code Block

xslt:templateName[?options]

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Maven users will need to add the following dependency to their pom.xml for this component when using Camel 2.8 or older:

Code Block
xml
xml

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-spring</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

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Wiki Markup
{div:class=confluenceTableSmall}
|| Name || Default Value || Description ||
| {{converter}} | {{null}} | Option to override default [XmlConverter|http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/converter/jaxp/XmlConverter.html]. Will lookup for the converter in the [Registry]. The provided converted must be of type org.apache.camel.converter.jaxp.XmlConverter. |
| {{transformerFactory}} | {{null}} | Option to override default [TransformerFactory|http://java.sun.com/j2se/1.5.0/docs/api/javax/xml/transform/TransformerFactory.html]. Will lookup for the transformerFactory in the [Registry]. The provided transformer factory must be of type javax.xml.transform.TransformerFactory. |
| {{transformerFactoryClass}} | {{null}} | Option to override default [TransformerFactory|http://java.sun.com/j2se/1.5.0/docs/api/javax/xml/transform/TransformerFactory.html]. Will create a TransformerFactoryClass instance and set it to the converter. |
| {{uriResolver}} | {{null}} | *Camel 2.3*: Allows you to use a custom {{javax.xml.transformation.URIResolver}}. Camel will by default use its own implementation {{org.apache.camel.builder.xml.XsltUriResolver}} which is capable of loading from classpath. |
| {{resultHandlerFactory}} | {{null}} | *Camel 2.3:* Allows you to use a custom {{org.apache.camel.builder.xml.ResultHandlerFactory}} which is capable of using custom {{org.apache.camel.builder.xml.ResultHandler}} types. |
| {{failOnNullBody}} | {{true}} | *Camel 2.3:* Whether or not to throw an exception if the input body is null. |
| {{deleteOutputFile}} | {{false}} | *Camel 2.6:* If you have {{output=file}} then this option dictates whether or not the output file should be deleted when the [Exchange] is done processing. For example suppose the output file is a temporary file, then it can be a good idea to delete it after use. |
| {{output}} | {{string}} | *Camel 2.3:* Option to specify which output type to use. Possible values are: {{string, bytes, DOM, file}}. The first three options are all in memory based, where as {{file}} is streamed directly to a {{java.io.File}}. For {{file}} you *must* specify the filename in the IN header with the key {{Exchange.XSLT_FILE_NAME}} which is also {{CamelXsltFileName}}. Also any paths leading to the filename must be created beforehand, otherwise an exception is thrown at runtime. |
| {{contentCache}} | {{true}} | *Camel 2.6:* Cache for the resource content (the stylesheet file) when it is loaded. If set to {{false}} Camel will reload the stylesheet file on each message processing. This is good for development. 
Note: from *Camel 2.9* a cached stylesheet can be forced to reload at runtime via JMX using the {{clearCachedStylesheet}} operation. |
| {{allowStAX}} | {{false}} | *Camel 2.8.3/2.9:* Whether to allow using StAX as the {{javax.xml.transform.Source}}. The option is default {{false}} in Camel 2.11.3/2.12.2 or older. And default {{true}} in Camel 2.11.4/2.12.3 onwards. |
| {{transformerCacheSize}} | {{0}} | *Camel 2.9.3/2.10.1:*  The number of {{javax.xml.transform.Transformer}} object that are cached for reuse to avoid calls to {{Template.newTransformer()}}. |
| {{saxon}} | {{false}} | *Camel 2.11:* Whether to use Saxon as the {{transformerFactoryClass}}. If enabled then the class {{net.sf.saxon.TransformerFactoryImpl}}. You would need to add Saxon to the classpath. |
{div}

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For example you could use something like

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from("activemq:My.Queue").
  to("xslt:com/acme/mytransform.xsl");

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If you want to use InOnly and consume the message and send it to another destination you could use the following route:

Code Block

from("activemq:My.Queue").
  to("xslt:com/acme/mytransform.xsl").
  to("activemq:Another.Queue");

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By default, all headers are added as parameters which are available in the XSLT.
To do this you will need to declare the parameter so it is then useable.

Code Block
xml
xml

<setHeader headerName="myParam"><constant>42</constant></setHeader>
<to uri="xslt:MyTransform.xsl"/>

And the XSLT just needs to declare it at the top level for it to be available:

Code Block
xml
xml

<xsl: ...... >

   <xsl:param name="myParam"/>
  
    <xsl:template ...>

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To use the above examples in Spring XML you would use something like

Code Block
xml
xml

  <camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
    <route>
      <from uri="activemq:My.Queue"/>
      <to uri="xslt:org/apache/camel/spring/processor/example.xsl"/>
      <to uri="activemq:Another.Queue"/>
    </route>
  </camelContext>

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For example this include:

Code Block
xml
xml

<xsl:include href="staff_template.xsl"/>

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For example this include:

Code Block
xml
xml

<xsl:include href="staff_template.xsl"/>

Will now be located relative from the starting endpoint, which for example could be:

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.to("xslt:org/apache/camel/component/xslt/staff_include_relative.xsl")

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You can also refer back in the paths such as

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    <xsl:include href="../staff_other_template.xsl"/>

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When using xsl:include such as:

Code Block
xml
xml

<xsl:include href="staff_template.xsl"/>

Then in Camel 2.10.3 and older, then Camel will use "classpath:" as the default prefix, and load the resource from the classpath. This works for most cases, but if you configure the starting resource to load from file,

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.to("xslt:file:etc/xslt/staff_include_relative.xsl")

.. then you would have to prefix all your includes with "file:" as well.

Code Block
xml
xml

<xsl:include href="file:staff_template.xsl"/>

From Camel 2.10.4 onwards we have made this easier as Camel will use the prefix from the endpoint configuration as the default prefix. So from Camel 2.10.4 onwards you can do:

Code Block
xml
xml

<xsl:include href="staff_template.xsl"/>

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In case anybody faces issues with the XSLT endpoint please review these points.

I was trying to use an xslt endpoint for a simple transformation from one xml to another using a simple xsl. The output xml kept appearing (after the xslt processor in the route) with outermost xml tag with no content within.

No explanations show up in the DEBUG logs. On the TRACE logs however I did find some error/warning indicating that the XMLConverter bean could no be initialized.

After a few hours of cranking my mind, I had to do the following to get it to work (thanks to some posts on the users forum that gave some clue):

1. Use the transformerFactory option in the route ("xslt:my-transformer.xsl?transformerFactory=tFactory") with the tFactory bean having bean defined in the spring context for class="org.apache.xalan.xsltc.trax.TransformerFactoryImpl".
2. Added the Xalan jar into my maven pom.

My guess is that the default xml parsing mechanism supplied within the JDK (I am using 1.6.0_03) does not work right in this context and does not throw up any error either. When I switched to Xalan this way it works. This is not a Camel issue, but might need a mention on the xslt component page.

Another note, jdk 1.6.0_03 ships with JAXB 2.0 while Camel needs 2.1. One workaround is to add the 2.1 jar to the jre/lib/endorsed directory for the jvm or as specified by the container.

Hope this post saves newbie Camel riders some time.

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