Transform referenced XML - content-management-system

Question

I have a pipeline question.
I have a workflow where I have a master XML that references multiple XML files. It would be similar to a DITA map, but this is not DITA.
I am having to run an XSLT on the master XML to prepare it for a downstream process for output to the web or other medium.
Part of this transform includes resolving database file paths to relative file paths within the package that is exported from the content management system.
I can perform the transformation on the master XML just fine. However, my question involves running a XSLT on the referenced XML files. They also need the paths corrected.
Here is a simple sample...
<master>
<reference url="x-database01.xml"/>
</master>
The reference will resolve to something like url="/files/realXMLname.xml". The problem is that I don't know how to then transform realXMLname.XML to resolve the paths there.
<content>
<graphic href="x-database02.jpg"/>
</content>
The database and the downstream process are 2 different software packages with an out-of-the-box integration. I could write my own pipeline to do the transforms, but it may be cost prohibitive. The current integration only allows for 1 XSLT to be run a the pre-process step.
Is it possible to transform referenced XML files in a single XSLT transform step?

Answer 1

The following setup uses a main input XML input.xml which only contains a root node and two other XML files part1.xml and part2.xml which are read using the document() function. The XSLT uses <xsl:apply-templates> to trigger the conversion of the union of the two XML files. This way it should be possible to combine any number of XML files beforehand into one tree and execute the XSLT process on the resulting tree.
By the way: It turns out that this is already supported in XSLT 1.0 (at least by the xsltproc processor).
File input.xml:
<?xml version="1.0" encoding="ISO-8859-1"?>
<root/>
File part1.xml:
<?xml version="1.0" encoding="ISO-8859-1"?>
<root1>
<element>
<subelement1 message="Hello from part1.xml"/>
</element>
</root1>
File 'part2.xml':
<?xml version="1.0" encoding="ISO-8859-1"?>
<root2>
<element>
<subelement2 message="Hello from part2.xml"/>
</element>
</root2>
With the input above the following XSLT transformation
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />
<xsl:variable name="part1" select="document('part1.xml')/root1"/>
<xsl:variable name="part2" select="document('part2.xml')/root2"/>
<xsl:template match="/">
<messages>
<xsl:apply-templates select="$part1|$part2"/>
</messages>
</xsl:template>
<xsl:template match="*">
<xsl:apply-templates/>
</xsl:template>
<xsl:template match="text()"/>
<xsl:template match="subelement1">
<message>
<xsl:value-of select="#message"/>
</message>
</xsl:template>
<xsl:template match="subelement2">
<message>
<xsl:value-of select="#message"/>
</message>
</xsl:template>
</xsl:stylesheet>
yields this output:
<?xml version="1.0" encoding="UTF-8"?>
<messages>
<message>Hello from part1.xml</message>
<message>Hello from part2.xml</message>
</messages>