XML Validation

Validation mode

<validation mode="auto">
        <entity-resolver>
            <catalog uri="${WEBAPP_HOME}/WEB-INF/catalog.xml" />
        </entity-resolver>
    </validation>

With the parameter mode it is possible to switch on/off the validation capabilities of the (Xerces) XML parser. The possible values are:

Catalog Entity Resolver

All grammars (XML schema, DTD) that are used for implicit validation must be registered with eXist using OASIS catalog files. These catalog files can be stored on disk and/or in the database itself. In eXist the actual resolving is performed by the apache xml-commons resolver library.

It is possible to configure any number of catalog entries in the entity-resolver section of conf.xml . The relative "uri="s are resolved relative to the location of the catalog document.

<validation mode="auto">
        <entity-resolver>
            <catalog uri="xmldb:exist:///db/grammar/catalog.xml" />
            <catalog uri="${WEBAPP_HOME}/WEB-INF/catalog.xml" />
        </entity-resolver>
    </validation>

A catalog stored in the database can be addressed by a URL like 'xmldb:exist:///db/mycollection/catalog.xml' (note the 3 leading slashes which imply localhost) or the shorter equivalent '/db/mycollection/catalog.xml'.

In the preceeding example ${WEBAPP_HOME} is substituted by a file:// URL pointing to the 'webapp'-directory of eXist (e.g. '$EXIST_HOME/webapp/') or the equivalent directory of a deployed WAR file when eXist is deployed in a servlet container (e.g. '${CATALINA_HOME}/webapps/exist/')

<?xml version="1.0" encoding="UTF-8"?>
    <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
        <public publicId="-//PLAY//EN" uri="entities/play.dtd"/>
        <system systemId="play.dtd" uri="entities/play.dtd"/>
        <system systemId="mondial.dtd" uri="entities/mondial.dtd"/>    
        
        <uri name="http://exist-db.org/samples/shakespeare" uri="entities/play.xsd"/>
        
        <uri name="http://www.w3.org/XML/1998/namespace" uri="entities/xml.xsd"/>
    	<uri name="http://www.w3.org/2001/XMLSchema" uri="entities/XMLSchema.xsd"/>
    
        <uri name="urn:oasis:names:tc:entity:xmlns:xml:catalog" uri="entities/catalog.xsd" />
    </catalog>

Collection configuration

Within the database the validation mode for each individal collection can be configured using collection.xconf documents, in the same way these are used for configuring indexes. These documents need to be stored in '/db/system/config/db/....'.

<?xml version='1.0'?>
<collection xmlns="http://exist-db.org/collection-config/1.0">
    <validation mode="no"/>
</collection>

This example xconf file turns the implicit validation off.

JAXP

The JAXP validation functions are based on the validation capabilities of the javax.xml.parsers API. The actual validation is performed by the Xerces2 library.

When parsing an XML document a reference to a grammar (either DTDs or XSDs) is found, then the parser attempts resolve the grammar reference by following either the XSD xsi:schemaLocation, xsi:noNamespaceSchemaLocation hints, the DTD DOCTYPE SYSTEM information, or by outsourcing the retrieval of the grammars to an Xml Catalog resolver. The resolver identifies XSDs by the (target)namespace, DTDs are identified by the PublicId.

Validation performance is increased through grammar caching; the cached compiled grammars are shared by the implicit validation feature.

The jaxp() and jaxp-report() functions accept the following parameters:

$instance

The XML instance document, referenced as document node (returned by fn:doc()), element node, xs:anyURI or as Java file object.

$cache-grammars

Set this to true() to enable grammar caching.

$catalogs

One or more OASIS catalog files referenced as xs:anyURI. Depending on the xs:anyURI a different resolver will be used:

• When an empty sequence is set, the catalog files defined in conf.xml are used.

• If the URI ends with ".xml" the specified catalog is used.

• If the URI points to a collection (when the URL ends with "/") the grammar files are searched in the database using an xquery. XSDs are found by their targetNamespace attributes, DTDs are found by their publicId entries in catalog files.

JAXV

The JAXV validation functions are based on the java.xml.validation API which has been introduced in Java 5 to provide a schema-language-independent interface to validation services. Although officially the specification allows use of additional schema languages, only XML schemas can be really used so far.

The jaxv() and jaxv-report() functions accept the following parameters:

$instance

The XML instance document, referenced as document node (returned by fn:doc()), element node, xs:anyURI or as Java file object.

$grammars

One or more grammar files, referenced as document nodes (returned by fn:doc()), element nodes, xs:anyURI or as Java file objects.

Jing

The Jing validation functions are based on James Clark's Jing library. eXist uses the maintained version that is available via Google Code. The library relies on the com.thaiopensource.validate.ValidationDriver which supports a wide range of grammar types:

• XML schema (.xsd)

• Namespace-based Validation Dispatching Language (.nvdl)

• RelaxNG (.rng and .rnc)

• Schematron 1.5 (.sch)

The jing() and jing-report() functions accept the following parameters:

$instance

The XML instance document, referenced as document node (returned by fn:doc()), element node, xs:anyURI or as Java file object.

$grammar

The grammar file, referenced as document node (returned by fn:doc()), element node, as xs:anyURI, binary document (returned by util:binary-doc() for RNC files) or as Java file object.