9.2. Content Filter
Overview
The content filter pattern describes a scenario where you need to filter out extraneous content from a message before delivering it to its intended recipient. For example, you might employ a content filter to strip out confidential information from a message.
Figure 9.2. Content Filter Pattern
A common way to filter messages is to use an expression in the DSL, written in one of the supported scripting languages (for example, XSLT, XQuery or JoSQL).
Implementing a content filter
A content filter is essentially an application of a message processing technique for a particular purpose. To implement a content filter, you can employ any of the following message processing techniques:
- Message translator—see message translators.
- Processors—see Chapter 43, Implementing a Processor.
XML configuration example
The following example shows how to configure the same route in XML:
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
<from uri="activemq:My.Queue"/>
<to uri="xslt:classpath:com/acme/content_filter.xsl"/>
<to uri="activemq:Another.Queue"/>
</route>
</camelContext>Using an XPath filter
You can also use XPath to filter out part of the message you are interested in:
<route> <from uri="activemq:Input"/> <setBody><xpath resultType="org.w3c.dom.Document">//foo:bar</xpath></setBody> <to uri="activemq:Output"/> </route>
