XProc

XProc

Filename extension	.xpl
Internet media type	application/xproc+xml
Developed by	World Wide Web Consortium
Type of format	Stylesheet language
Extended from	XML
Standard	1.0 (Recommendation)

XProc is a W3C Recommendation to define an XML transformation language to define XML Pipelines.

Below is an example abbreviated XProc file:

<p:pipeline name="pipeline" xmlns:p="http://www.w3.org/ns/xproc" version="1.0">
  <p:input port="schemas" sequence="true"/>

  <p:xinclude/>

  <p:validate-with-xml-schema>
    <p:input port="schema">
      <p:pipe step="pipeline" port="schemas"/>
    </p:input>
  </p:validate-with-xml-schema>
</p:pipeline>

This is a pipeline that consists of two atomic steps, XInclude and Validate. The pipeline itself has three inputs, “source” (a source document), “schemas” (a list of W3C XML Schemas) and “parameters” (for passing parameters). The XInclude step reads the pipeline input “source” and produces a result document. The Validate step reads the pipeline input “schemas” and the output from the XInclude step and produces a result document. The result of the validation, “result”, is the result of the pipeline.

Here is an equivalent less abbreviated XProc pipeline:

<p:pipeline name="pipeline" xmlns:p="http://www.w3.org/ns/xproc" 
  version="1.0">
  <p:input port="schemas" sequence="true"/>

  <p:xinclude name="included">
    <p:input port="source">
      <p:pipe step="pipeline" port="source"/>
    </p:input>
  </p:xinclude>

  <p:validate-with-xml-schema name="validated">
    <p:input port="source">
      <p:pipe step="included" port="result"/>
    </p:input>
    <p:input port="schema">
      <p:pipe step="pipeline" port="schemas"/>
    </p:input>
  </p:validate-with-xml-schema>
</p:pipeline>

Implementations

• Calabash maintained by Norman Walsh
• Calumet, EMC’s XProc implementation
• QuiXProc, Innovimax's (GPL) version in Java implementing Streaming and Parallel processing
• Tubular (LGPL) maintained by Herve Quiroz
• xprocxq, XQuery old implementation on top of eXist
• xproc.xq, XQuery implementation on top of MarkLogic

See also

• XSLT
• XPath

External links

• The XML Processing Model Working Group page at W3C
• The W3C Recommendation
• The web site maintained by Norman Walsh
• XProc tutorial
• XProc reference