The FastXSLT Mediator is similar to the XSLT mediator, but it uses the Streaming XPath Parser and applies the XSLT transformation to the message stream instead of to the XML message payload. The result is a faster transformation, but you cannot specify the source, properties, features, or resources as you can with the XSLT mediator.
FastXSLT mediator is intended to be used with messages which that are not being built before the mediator receives the message. Any pre-processing performed on the message payload will not be visible to the fastXSLT FastXSLT mediator since , because the transformation logic is applied on the original message stream instead of the message payload. In cases where message payload needs to be pre-processed, use the XSLT mediator can be used instead of fastXSLT the FastXSLT mediator.
To enable the FastXSLT mediator, your XSLT script must include the following parameter in the XSL output:
omit-xml-declaration="yes"<xsl:output method="xml" omit-xml-declaration="yes" encoding="UTF-8" indent="yes"/>
...