[[schematron-component]]
== Schematron Component

*Available as of Camel version 2.15*

http://www.schematron.com/index.html[Schematron] is an XML-based
language for validating XML instance documents. It is used to make
assertions about data in an XML document and it is also used to express
operational and business rules. Schematron is
an http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html[ISO
Standard]. The schematron component uses the leading
http://www.schematron.com/implementation.html[implementation] of ISO
schematron. It is an XSLT based implementation. The schematron rules is
run through http://www.schematron.com/implementation.html[four XSLT
pipelines], which generates a final XSLT which will be used as the basis
for running the assertion against the XML document. The component is
written in a way that Schematron rules are loaded at the start of the
endpoint (only once) this is to minimise the overhead of instantiating a
Java Templates object representing the rules.

### URI format

[source,java]
---------------------------
schematron://path?[options]
---------------------------

### URI options


// component options: START
The Schematron component has no options.
// component options: END





// endpoint options: START
The Schematron endpoint is configured using URI syntax:

----
schematron:path
----

with the following path and query parameters:

==== Path Parameters (1 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *path* | *Required* The path to the schematron rules file. Can either be in class path or location in the file system. |  | String
|===


==== Query Parameters (4 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *abort* (producer) | Flag to abort the route and throw a schematron validation exception. | false | boolean
| *rules* (producer) | To use the given schematron rules instead of loading from the path |  | Templates
| *synchronous* (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean
| *uriResolver* (advanced) | Set the URIResolver to be used for resolving schematron includes in the rules file. |  | URIResolver
|===
// endpoint options: END
// spring-boot-auto-configure options: START
=== Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

[source,xml]
----
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-schematron-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>
----


The component supports 2 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *camel.component.schematron.enabled* | Enable schematron component | true | Boolean
| *camel.component.schematron.resolve-property-placeholders* | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | Boolean
|===
// spring-boot-auto-configure options: END





### Headers

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Name |Description |Type |In/Out

|CamelSchematronValidationStatus |The schematron validation status: SUCCESS / FAILED |String |IN

|CamelSchematronValidationReport |The schematrion report body in XML format. See an example below |String |IN
|=======================================================================

### URI and path syntax

The following example shows how to invoke the schematron processor in
Java DSL. The schematron rules file is sourced from the class path:

[source,java]
----------------------------------------------------------------------------
from("direct:start").to("schematron://sch/schematron.sch").to("mock:result")
----------------------------------------------------------------------------

 

The following example shows how to invoke the schematron processor in
XML DSL. The schematrion rules file is sourced from the file system:

[source,xml]
-----------------------------------------------------------------------------------------------
<route>
   <from uri="direct:start" />
   <to uri="schematron:///usr/local/sch/schematron.sch" />
   <log message="Schematron validation status: ${in.header.CamelSchematronValidationStatus}" />
   <choice>
      <when>
         <simple>${in.header.CamelSchematronValidationStatus} == 'SUCCESS'</simple>
         <to uri="mock:success" />
      </when>
      <otherwise>
         <log message="Failed schematron validation" />
         <setBody>
            <header>CamelSchematronValidationReport</header>
         </setBody>
         <to uri="mock:failure" />
      </otherwise>
   </choice>
</route>
-----------------------------------------------------------------------------------------------

TIP: *Where to store schematron rules?*
Schematron rules can change with business requirement, as such it is
recommended to store these rules somewhere in file system. When the
schematron component endpoint is started, the rules are compiled into
XSLT as a  Java Templates Object. This is done only once to minimise the
overhead of instantiating Java Templates object, which can be an
expensive operation for large set of rules and given that the process
goes through four pipelines
of http://www.schematron.com/implementation.html[XSLT transformations].
So if you happen to store the rules in the file system, in the event of
an update, all you need is to restart the route or the component. No
harm in storing these rules in the class path though, but you will have
to build and deploy the component to pick up the changes.

### Schematron rules and report samples

Here is an example of schematron rules

[source,xml]
--------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://purl.oclc.org/dsdl/schematron">
   <title>Check Sections 12/07</title>
   <pattern id="section-check">
      <rule context="section">
         <assert test="title">This section has no title</assert>
         <assert test="para">This section has no paragraphs</assert>
      </rule>
   </pattern>
</schema>
--------------------------------------------------------------------

Here is an example of schematron report:

[source,xml]
------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<svrl:schematron-output xmlns:svrl="http://purl.oclc.org/dsdl/svrl"
 xmlns:iso="http://purl.oclc.org/dsdl/schematron"
 xmlns:saxon="http://saxon.sf.net/"
 xmlns:schold="http://www.ascc.net/xml/schematron"
 xmlns:xhtml="http://www.w3.org/1999/xhtml"
 xmlns:xs="http://www.w3.org/2001/XMLSchema"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema" schemaVersion="" title="">
   
   <svrl:active-pattern document="" />
   <svrl:fired-rule context="chapter" />
   <svrl:failed-assert test="title" location="/doc[1]/chapter[1]">
      <svrl:text>A chapter should have a title</svrl:text>
   </svrl:failed-assert>
   <svrl:fired-rule context="chapter" />
   <svrl:failed-assert test="title" location="/doc[1]/chapter[2]">
      <svrl:text>A chapter should have a title</svrl:text>
   </svrl:failed-assert>
   <svrl:fired-rule context="chapter" />
</svrl:schematron-output>
------------------------------------------------------------------------

TIP: *Useful Links and resources*
* http://www.mulberrytech.com/papers/schematron-Philly.pdf[Introduction
to Schematron] by Mulleberry technologies. An excellent document in PDF
to get you started on Schematron.
* http://www.schematron.com[Schematron official site]. This contains
links to other resources
