The pipeline
<p:declare-step xmlns:c="http://www.w3.org/ns/xproc-step" xmlns:p="http://www.w3.org/ns/xproc" xmlns:xs="http://www.w3.org/2001/XMLSchema" name="main" version="3.0">
<p:output port="result"/>
<p:identity name="producer">
<p:with-input>
<doc a="1"/>
</p:with-input>
</p:identity>
<p:identity name="id">
<p:with-input port="source">
<p:document document-properties="map { 'a': xs:integer(/doc/@a) }" href="../documents/ab-doc.xml"/>
</p:with-input>
</p:identity>
<p:cast-content-type content-type="application/xml">
<p:with-input port="source" select="p:document-properties(.)"/>
</p:cast-content-type>
</p:declare-step>
Schematron validation
<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:ns prefix="j" uri="http://www.w3.org/2005/xpath-functions"/>
<s:pattern>
<s:rule context="/">
<s:assert test="j:map">The pipeline root is not “map”.</s:assert>
<s:assert test="j:map/j:number[@key='a']">Element does not has an attribute 'key' with value 'a'.</s:assert>
<s:assert test="j:map/j:number/text() = '1'">The property value is not 1</s:assert>
</s:rule>
</s:pattern>
</s:schema>
