I would like to speed up the process of validating a batch of XML files against the same single XML schema (XSD). Only restrictions are that I am in a PHP environment.
My current problem is that the schema I would like to validate against includes the fairly complex xhtml schema of 2755 lines (http://www.w3.org/2002/08/xhtml/xhtml1-transitional.xsd). Even for very simple data this takes a long time (around 30 seconds pr. validation). As I have thousands of XML files in my batch, this doesn't really scale well.
For validating the XML file I use both of these methods, from the standard php-xml libraries.
- DOMDocument::schemaValidate
- DOMDocument::schemaValidateSource
I am thinking that the PHP implementation fetches the XHTML schema via HTTP and builds some internal representation (possibly a DOMDocument) and that this is thrown away when the validation is completed. I was thinking that some option for the XML-libs might change this behaviour to cache something in this process for reuse.
I've build a simple test setup which illustrates my problem:
<xs:schema attributeFormDefault="unqualified"
elementFormDefault="qualified"
targetNamespace="http://myschema.example.com/"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:myschema="http://myschema.example.com/"
xmlns:xhtml="http://www.w3.org/1999/xhtml">
<xs:import
schemaLocation="http://www.w3.org/2002/08/xhtml/xhtml1-transitional.xsd"
namespace="http://www.w3.org/1999/xhtml">
</xs:import>
<xs:element name="Root">
<xs:complexType>
<xs:sequence>
<xs:element name="MyHTMLElement">
<xs:complexType>
<xs:complexContent>
<xs:extension base="xhtml:Flow"></xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
<?xml version="1.0" encoding="UTF-8"?>
<Root xmlns="http://myschema.example.com/" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:xml="http://www.w3.org/XML/1998/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://myschema.example.com/ test-schema.xsd ">
<MyHTMLElement>
<xhtml:p>This is an XHTML paragraph!</xhtml:p>
</MyHTMLElement>
</Root>
<?php
$data_dom = new DOMDocument();
$data_dom->load('test-data.xml');
// Multiple validations using the schemaValidate method.
for ($attempt = 1; $attempt <= 3; $attempt++) {
$start = time();
echo "schemaValidate: Attempt #$attempt returns ";
if (!$data_dom->schemaValidate('test-schema.xsd')) {
echo "Invalid!";
} else {
echo "Valid!";
}
$end = time();
echo " in " . ($end-$start) . " seconds.\n";
}
// Loading schema into a string.
$schema_source = file_get_contents('test-schema.xsd');
// Multiple validations using the schemaValidate method.
for ($attempt = 1; $attempt <= 3; $attempt++) {
$start = time();
echo "schemaValidateSource: Attempt #$attempt returns ";
if (!$data_dom->schemaValidateSource($schema_source)) {
echo "Invalid!";
} else {
echo "Valid!";
}
$end = time();
echo " in " . ($end-$start) . " seconds.\n";
}
Running this schematest.php file produces the following output:
schemaValidate: Attempt #1 returns Valid! in 30 seconds.
schemaValidate: Attempt #2 returns Valid! in 30 seconds.
schemaValidate: Attempt #3 returns Valid! in 30 seconds.
schemaValidateSource: Attempt #1 returns Valid! in 32 seconds.
schemaValidateSource: Attempt #2 returns Valid! in 30 seconds.
schemaValidateSource: Attempt #3 returns Valid! in 30 seconds.
Any help and suggestions on how to solve this issue, are very welcomed!