XML validation

From Rosetta Code
XML validation is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Given an XML document and an XSD schema definition validate that the document follows the schema described.

Sample XML and XSD for tests can be found on this W3 Schools page.

C

Library: LibXML

At the time of writing, the XML and XSD files at the URLs used in the other examples were inaccessible. The files from the W3 Schools page were used for tests. <lang C>

  1. include <libxml/xmlschemastypes.h>

int main(int argC, char** argV) { if (argC <= 2) { printf("Usage: %s <XML Document Name> <XSD Document Name>\n", argV[0]); return 0; }

xmlDocPtr doc; xmlSchemaPtr schema = NULL; xmlSchemaParserCtxtPtr ctxt; char *XMLFileName = argV[1]; char *XSDFileName = argV[2]; int ret;

xmlLineNumbersDefault(1);

ctxt = xmlSchemaNewParserCtxt(XSDFileName);

xmlSchemaSetParserErrors(ctxt, (xmlSchemaValidityErrorFunc) fprintf, (xmlSchemaValidityWarningFunc) fprintf, stderr); schema = xmlSchemaParse(ctxt); xmlSchemaFreeParserCtxt(ctxt);


doc = xmlReadFile(XMLFileName, NULL, 0);

if (doc == NULL){ fprintf(stderr, "Could not parse %s\n", XMLFileName); } else{ xmlSchemaValidCtxtPtr ctxt;

ctxt = xmlSchemaNewValidCtxt(schema); xmlSchemaSetValidErrors(ctxt, (xmlSchemaValidityErrorFunc) fprintf, (xmlSchemaValidityWarningFunc) fprintf, stderr); ret = xmlSchemaValidateDoc(ctxt, doc);

if (ret == 0){ printf("%s validates\n", XMLFileName); } else if (ret > 0){ printf("%s fails to validate\n", XMLFileName); } else{ printf("%s validation generated an internal error\n", XMLFileName); } xmlSchemaFreeValidCtxt(ctxt); xmlFreeDoc(doc); }


if(schema != NULL) xmlSchemaFree(schema);

xmlSchemaCleanupTypes(); xmlCleanupParser(); xmlMemoryDump();

return 0; } </lang> Output, files used from the W3 Schools page : 

C:\rosettaCode>xmlValidator.exe shiporder.xml shiporder.xsd
shiporder.xml validates

C#

<lang csharp> using System; using System.Xml; using System.Xml.Schema; using System.IO;

public class Test { public static void Main() { // your code goes here XmlSchemaSet sc = new XmlSchemaSet(); sc.Add(null, "http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd"); XmlReaderSettings settings = new XmlReaderSettings(); settings.ValidationType = ValidationType.Schema; settings.Schemas = sc; settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack); // Create the XmlReader object. XmlReader reader = XmlReader.Create("http://venus.eas.asu.edu/WSRepository/xml/Courses.xml", settings); // Parse the file. while (reader.Read()); // will call event handler if invalid Console.WriteLine("The XML file is valid for the given xsd file"); }

// Display any validation errors. private static void ValidationCallBack(object sender, ValidationEventArgs e) { Console.WriteLine("Validation Error: {0}", e.Message); } } </lang>

F#

Using an inline stylesheet:

<lang fsharp>open System.Xml open System.Xml.Schema open System.IO

let xml = @"<root> <xs:schema id='an-element' targetNamespace='example' xmlns:mstns='example' xmlns='example' xmlns:xs='http://www.w3.org/2001/XMLSchema' attributeFormDefault='unqualified' elementFormDefault='qualified'> 

 <xs:element name='an-element'>
   <xs:complexType>
     <xs:sequence minOccurs='0' maxOccurs='unbounded'>
       <xs:element name='another-element' nillable='true'>
         <xs:complexType>
           <xs:simpleContent>
             <xs:extension base='xs:string'>
               <xs:attribute name='an-attribute' form='unqualified' type='xs:boolean' />
             </xs:extension>
           </xs:simpleContent>
         </xs:complexType>
       </xs:element>
     </xs:sequence>
   </xs:complexType>
 </xs:element>

</xs:schema> <an-element xmlns='example'> 

   <another-element an-attribute='false'>...</another-element>
   <another-element an-attribute='wrong'>123</another-element>

</an-element> </root>"

let validationData withWarnings = 

   let errors = ref 0
   let warnings = ref 0
   fun input ->
       match input with
       | Some(msg, severity) ->
           if severity = XmlSeverityType.Error then
               errors := !errors + 1
               printfn "Validation error: %s" msg
           elif withWarnings then
               warnings := !warnings + 1
               printfn "Validation warning: %s" msg
           None
       | None ->
           if withWarnings then
               Some(dict[XmlSeverityType.Error, !errors; XmlSeverityType.Warning, !warnings])
           else
               Some(dict[XmlSeverityType.Error, !errors])

[<EntryPoint>] let main argv = 

   let withWarnings = argv.Length > 0 && argv.[0] = "-w"
   let vData = validationData withWarnings
   let validationEvent = new ValidationEventHandler(fun _ e ->
       vData (Some(e.Message, e.Severity)) |> ignore)
   let settings = new XmlReaderSettings()
   settings.ValidationType <- ValidationType.Schema
   settings.ValidationEventHandler.AddHandler(validationEvent)
   settings.ValidationFlags <- settings.ValidationFlags ||| XmlSchemaValidationFlags.ProcessInlineSchema ||| XmlSchemaValidationFlags.ReportValidationWarnings
   let reader = XmlReader.Create(new StringReader(xml), settings);
   while reader.Read() do ()
   printfn "%A" (Seq.toList (vData None).Value)
   0

</lang>

Output:
>RosettaCode
Validation error: The 'an-attribute' element is invalid - The value 'wrong' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'wrong' is not a valid boolean value.
[[Error, 1]]

>RosettaCode -w
Validation warning: Could not find schema information for the element 'root'.
Validation error: The 'an-attribute' element is invalid - The value 'wrong' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'wrong' is not a valid boolean value.
[[Error, 1]; [Warning, 1]]

Changing wrong to a boolean, e. g. true, The result (without -w) is 

[[Error, 0]]

Go

Library: libxml2(Go)


This uses the w3schools test data linked to above. <lang go>package main

import ( 

   "fmt"
   "github.com/lestrrat-go/libxml2"
   "github.com/lestrrat-go/libxml2/xsd"
   "io/ioutil"
   "log"
   "os"

)

func check(err error) { 

   if err != nil {
       log.Fatal(err)
   }

}

func main() { 

   xsdfile := "shiporder.xsd"
   f, err := os.Open(xsdfile)
   check(err)
   defer f.Close()

   buf, err := ioutil.ReadAll(f)
   check(err)

   s, err := xsd.Parse(buf)
   check(err)
   defer s.Free()

   xmlfile := "shiporder.xml"
   f2, err := os.Open(xmlfile)
   check(err)
   defer f2.Close()

   buf2, err := ioutil.ReadAll(f2)
   check(err)

   d, err := libxml2.Parse(buf2)
   check(err)

   if err := s.Validate(d); err != nil {
       for _, e := range err.(xsd.SchemaValidationError).Errors() {
           log.Printf("error: %s", e.Error())
       }
       return
   }

   fmt.Println("Validation of", xmlfile, "against", xsdfile, "successful!")

}</lang>

Output:
Validation of shiporder.xml against shiporder.xsd successful!

Groovy

Translation of: Java

Solution: <lang groovy>import static javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI import javax.xml.transform.stream.StreamSource import javax.xml.validation.SchemaFactory import org.xml.sax.SAXParseException

def factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI) def validate = { schemaURL, docURL -> 

   try {
       factory.newSchema(schemaURL.toURL()).newValidator().validate(new StreamSource(docURL))
       true
   } catch (SAXParseException e) {
       false
   }

}</lang>

Test: <lang groovy>def schemaLoc = "http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd" def docLoc = "http://venus.eas.asu.edu/WSRepository/xml/Courses.xml" println "Document is ${validate(schemaLoc, docLoc)? 'valid' : 'invalid'}"</lang>

Java

<lang java>import static javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI;

import java.net.MalformedURLException; import java.net.URL;

import javax.xml.transform.stream.StreamSource; import javax.xml.validation.SchemaFactory; import javax.xml.validation.Validator; import javax.xml.ws.Holder;

import org.xml.sax.ErrorHandler; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException;

public class XmlValidation { public static void main(String... args) throws MalformedURLException { URL schemaLocation = new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd"); URL documentLocation = new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xml"); if (validate(schemaLocation, documentLocation)) { System.out.println("document is valid"); } else { System.out.println("document is invalid"); } }

// The least code you need for validation public static boolean minimalValidate(URL schemaLocation, URL documentLocation) { SchemaFactory factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI); try { Validator validator = factory.newSchema(schemaLocation).newValidator(); validator.validate(new StreamSource(documentLocation.toString())); return true; } catch (Exception e) { return false; } }

// A more complete validator public static boolean validate(URL schemaLocation, URL documentLocation) { SchemaFactory factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI); final Holder<Boolean> valid = new Holder<>(true); try { Validator validator = factory.newSchema(schemaLocation).newValidator(); // Get some better diagnostics out validator.setErrorHandler(new ErrorHandler(){ @Override public void warning(SAXParseException exception) { System.out.println("warning: " + exception.getMessage()); }

@Override public void error(SAXParseException exception) { System.out.println("error: " + exception.getMessage()); valid.value = false; }

@Override public void fatalError(SAXParseException exception) throws SAXException { System.out.println("fatal error: " + exception.getMessage()); throw exception; }}); validator.validate(new StreamSource(documentLocation.toString())); return valid.value; } catch (SAXException e) { // Already reported above return false; } catch (Exception e) { // If this is the only thing that throws, it's a gross error System.err.println(e); return false; } } }</lang>

Julia

<lang julia>using LightXML

const Xptr= LightXML.Xptr

function validate(url::String, schemafile::String) 

   ctxt = ccall((:xmlSchemaNewParserCtxt, LightXML.libxml2), Xptr, (Cstring,), schemafile)
   ctxt != C_NULL || throw(LightXML.XMLNoRootError())
   schema = ccall((:xmlSchemaParse, LightXML.libxml2), Xptr, (Xptr,), ctxt)
   schema != C_NULL || throw(LightXML.XMLNoRootError())
   ccall((:xmlSchemaFreeParserCtxt, LightXML.libxml2), Cvoid, (Xptr,), ctxt)
   ctxt = ccall((:xmlSchemaNewValidCtxt, LightXML.libxml2), Xptr, (Xptr,), schema)
   err = ccall((:xmlSchemaValidateFile, LightXML.libxml2), 
       Cint, (Ptr{LightXML.xmlBuffer}, Cstring), ctxt, url)
   return err == 0 ? true : false

end

function xsdvalidatexml() if length(ARGS) != 2 println(" Usage: julia ", PROGRAM_FILE, ", xmlfilename xsdfilename") elseif validate(ARGS[1], ARGS[2]) println("File ", ARGS[1], " validates as correct XML using the XSD file ", ARGS[2], ".") else println("File ", ARGS[1]. "does not validate.") end end

xsdvalidatexml() </lang>

Kotlin

Translation of: C
Library: libxml2
Works with: Ubuntu 14.04

Assuming that libxml2 is already installed on your system in the default location(s), you first need to build libxml_schemas.klib using the following .def file and the cinterop tool: 

// libxml_schemas.def
headers = /usr/include/libxml2/libxml/xmlschemastypes.h
compilerOpts = -I/usr/include/libxml2
linkerOpts = -L/usr/lib/x86_64-linux-gnu -lxml2

Next, you need to compile the following Kotlin program, linking against libxml_schemas.klib. <lang scala>// Kotlin Native v0.6

import kotlinx.cinterop.* import platform.posix.* import libxml_schemas.*

fun err(ctx: COpaquePointer?, msg: CPointer<ByteVar>?, extra: CPointer<ByteVar>?) { 

   val fp = ctx?.reinterpret<FILE>()
   fprintf(fp, msg?.toKString(), extra?.toKString())

}

fun warn(ctx: COpaquePointer?, msg: CPointer<ByteVar>?, extra: CPointer<ByteVar>?) { 

   err(ctx, msg, extra)

}

fun main(args: Array<String>) { 

   if (args.size != 2) {
       println("You need to pass exactly 2 command line arguments, namely:")
       println("    <XML Document Name> <XSD Document Name>")
       return
   }

   val xmlFileName = args[0]
   val xsdFileName = args[1]
   xmlLineNumbersDefault(1)
   val ctxt = xmlSchemaNewParserCtxt(xsdFileName)

   xmlSchemaSetParserErrors(
       ctxt,
       staticCFunction(::err) as xmlSchemaValidityErrorFunc?,
       staticCFunction(::warn) as xmlSchemaValidityWarningFunc?,
       stderr
   )

   val schema = xmlSchemaParse(ctxt)
   xmlSchemaFreeParserCtxt(ctxt)

   val doc = xmlReadFile(xmlFileName, null, 0)
   if (doc == null) {
       println("Could not parse $xmlFileName")
   }
   else {
       val ctxt2 = xmlSchemaNewValidCtxt(schema)

       xmlSchemaSetValidErrors(
           ctxt2,
           staticCFunction(::err) as xmlSchemaValidityErrorFunc?,
           staticCFunction(::warn) as xmlSchemaValidityWarningFunc?,
           stderr
       )

       val ret = xmlSchemaValidateDoc(ctxt2, doc)
       if (ret == 0)
           println("$xmlFileName validates")
       else if (ret > 0)
           println("$xmlFileName fails to validate")
       else
           println("$xmlFileName generated an internal error")
       xmlSchemaFreeValidCtxt(ctxt2)
       xmlFreeDoc(doc)
   }

   if (schema != null) xmlSchemaFree(schema)
   xmlSchemaCleanupTypes()
   xmlCleanupParser()
   xmlMemoryDump()

}</lang> Finally, the resulting .kexe file should be executed passing it similar command line arguments to the C entry to produce the following output. 

$ ./xmlval.kexe shiporder.xml shiporder.xsd
shiporder.xml validates

Perl

<lang perl>#!/usr/bin/env perl -T use 5.018_002; use warnings; use Try::Tiny; use XML::LibXML;

our $VERSION = 1.000_000;

my $parser = XML::LibXML->new();

my $good_xml = '<a>5</a>'; my $bad_xml = '<a>5foobar</a>'; my $xmlschema_markup = <<'END'; <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

 <xsd:element name="a" type="xsd:integer"/>

</xsd:schema> END

my $xmlschema = XML::LibXML::Schema->new( string => $xmlschema_markup );

for ( $good_xml, $bad_xml ) { 

   my $doc = $parser->parse_string($_);
   try {
       $xmlschema->validate($doc);
   }
   finally {
       if (@_) {
           say "Not valid: @_";
       }
       else {
           say 'Valid';
       }
   };

}</lang>

Output:
Valid
Not valid: unknown-7fe99976a9a0:0: Schemas validity error :
  Element 'a': Element content is not allowed, because the type definition is simple.

Python

<lang python>#!/bin/python from __future__ import print_function import lxml from lxml import etree

if __name__=="__main__":

parser = etree.XMLParser(dtd_validation=True) schema_root = etree.XML(\ <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="a" type="xsd:integer"/> </xsd:schema> ) schema = etree.XMLSchema(schema_root)

#Good xml parser = etree.XMLParser(schema = schema) try: root = etree.fromstring("<a>5</a>", parser) print ("Finished validating good xml") except lxml.etree.XMLSyntaxError as err: print (err)

#Bad xml parser = etree.XMLParser(schema = schema) try: root = etree.fromstring("<a>5foobar</a>", parser) except lxml.etree.XMLSyntaxError as err: print (err)</lang>

Output:
Finished validating good xml
Element 'a': Element content is not allowed, because the type definition is simple.

Raku

(formerly Perl 6)

Translation of: Perl

<lang perl6>

  1. Reference: https://github.com/p6-xml/LibXML-p6

use v6.d; use LibXML; use LibXML::Schema;

my $good_xml = '<a>5</a>'; my $bad_xml = '<a>5foobar</a>';

my $xsdschema = q:to<EOF>; 

  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
     <xsd:element name="a" type="xsd:integer"/>
  </xsd:schema>

EOF

my LibXML $p .= new();

for ( $good_xml, $bad_xml ) { 

  my $x = $p.parse: :string($_);
  try { LibXML::Schema.new( string => $xsdschema ).validate( $x ) }
  !$! ?? say "Valid." !! say $!.message() ;

}</lang>

Output:
Valid.
Schemas validity error : Element 'a': Element content is not allowed, because the type definition is simple.

Scala

 <lang Scala>import java.net.URL

import javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI import javax.xml.transform.stream.StreamSource import javax.xml.validation.SchemaFactory import javax.xml.ws.Holder import org.xml.sax.{ErrorHandler, SAXException, SAXParseException}

object XmlValidation extends App { 

 val (schemaLocation, documentLocation) = (new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd")
   , new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xml"))

 println(s"Document is ${if (validate(schemaLocation, documentLocation)) "valid" else "invalid"}.")

 // A more complete validator
 def validate(schemaLocation: URL, documentLocation: URL): Boolean = {
   val factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI)
   val valid = new Holder[Boolean](true)
   try {
     val validator = factory.newSchema(schemaLocation).newValidator
     // Get some better diagnostics out
     validator.setErrorHandler(new ErrorHandler() {
       override def warning(exception: SAXParseException) = println("warning: " + exception.getMessage)

       override def error(exception: SAXParseException) = {
         println("error: " + exception.getMessage)
         valid.value = false
       }

       override def fatalError(exception: SAXParseException) = {
         println("fatal error: " + exception.getMessage)
         throw exception
       }
     })
     validator.validate(new StreamSource(documentLocation.toString))
     valid.value
   } catch {
     case _: SAXException =>
       // Already reported above
       false
     case e: Exception =>
       // If this is the only thing that throws, it's a gross error
       println(e)
       false
   }
 }

}</lang>

Sidef

Translation of: Perl

<lang ruby>require('XML::LibXML')

func is_valid_xml(str, schema) { 

   var parser    = %O<XML::LibXML>.new
   var xmlschema = %O<XML::LibXML::Schema>.new(string => schema)

   try {
       xmlschema.validate(parser.parse_string(str))
       true
   } catch {
       false
   }

}

var good_xml = '<a>5</a>' var bad_xml = '<a>5foobar</a>'

var xmlschema_markup = <<'END' <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

 <xsd:element name="a" type="xsd:integer"/>

</xsd:schema> END

[good_xml, bad_xml].each { |xml| 

   say "is_valid_xml(#{xml.dump}) : #{is_valid_xml(xml, xmlschema_markup)}"

}</lang>

Output:
is_valid_xml("<a>5</a>") : true
is_valid_xml("<a>5<b>foobar</b></a>") : false

Visual Basic .NET

Compiler: Roslyn Visual Basic (language version >= 14, e.g. with Visual Studio 2015)

Works with: .NET Core version 2.1

<lang vbnet>Option Compare Binary Option Explicit On Option Infer On Option Strict On

Imports System.Xml Imports System.Xml.Schema

Module Program 

   Function GetValidationErrors(doc As XDocument, schemaSet As XmlSchemaSet) As IList(Of ValidationEventArgs)
       GetValidationErrors = New List(Of ValidationEventArgs)
       doc.Validate(schemaSet, Sub(sender, e) GetValidationErrors.Add(e))
   End Function

   Sub Main()
       ' These functions are declared in another module found below.
       Dim schema = GetSchema()
       Dim document = GetDocument()

       Dim schemaSet As New XmlSchemaSet()
       schemaSet.Add(XmlSchema.Read(schema.CreateReader(), Nothing))

       Dim errors = GetValidationErrors(document, schemaSet)
       For Each e In errors
           Console.WriteLine($"Validation {e.Severity}:{vbCrLf}{e.Message}")
       Next

       If errors.Count = 0 Then Console.WriteLine("The document is valid.")
   End Sub

End Module</lang>

Output:
Validation Error:
The 'an-attribute' attribute is invalid - The value 'wrong' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'wrong' is not a valid Boolean value.

An alternative is to use XmlReader (like the C# and F# examples [as of 2019-08-06]).

<lang vbnet> Function GetValidationErrorsXmlReader(doc As XDocument, schemaSet As XmlSchemaSet, warnings As Boolean) As IList(Of ValidationEventArgs) 

       GetValidationErrorsReader = New List(Of ValidationEventArgs)

       Dim settings As New XmlReaderSettings()
       With settings
           .ValidationType = ValidationType.Schema
           .Schemas = schemaSet
           If warnings Then .ValidationFlags = .ValidationFlags Or XmlSchemaValidationFlags.ReportValidationWarnings
       End With

       AddHandler settings.ValidationEventHandler, Sub(sender, e) GetValidationErrorsReader.Add(e)

       Using reader = XmlReader.Create(doc.CreateReader(), settings)
           Do While reader.Read() : Loop
       End Using
   End Function</lang>

Creating the documents (same as F#) from strings (does not handle syntax errors):

<lang vbnet>Module Constants 

   Const SCHEMA As String =

"<?xml version='1.0'?> <xs:schema id='an-element' targetNamespace='example' xmlns:mstns='example' xmlns='example' xmlns:xs='http://www.w3.org/2001/XMLSchema' attributeFormDefault='unqualified' elementFormDefault='qualified'> 

   <xs:element name='an-element'>
       <xs:complexType>
           <xs:sequence minOccurs='0' maxOccurs='unbounded'>
               <xs:element name='another-element' nillable='true'>
                   <xs:complexType>
                       <xs:simpleContent>
                           <xs:extension base='xs:string'>
                               <xs:attribute name='an-attribute' form='unqualified' type='xs:boolean'/>
                           </xs:extension>
                       </xs:simpleContent>
                   </xs:complexType>
               </xs:element>
           </xs:sequence>
       </xs:complexType>
   </xs:element>

</xs:schema>" 

   Const DOCUMENT As String =

"<?xml version='1.0'?> <an-element xmlns='example'> 

   <another-element an-attribute='false'>...</another-element>
   <another-element an-attribute='wrong'>123</another-element>

</an-element>" 

   Function GetSchema() As XDocument
       Return XDocument.Parse(SCHEMA)
   End Function

   Function GetDocument() As XDocument
       Return XDocument.Parse(DOCUMENT)
   End Function

End Module</lang>

Alternatively, we can be cheeky and use VB's XML literals...

<lang vbnet>Module Constants 

   Function GetDocument() As XDocument
       Return _
       <?xml version="1.0"?>
       <an-element xmlns="example">
           <another-element an-attribute="false">...</another-element>
           <another-element an-attribute="wrong"> 123</another-element>
       </an-element>
   End Function

   Function GetSchema() As XDocument
       Return _
       <?xml version="1.0"?>
       <xs:schema id="an-element" targetNamespace="example" xmlns:mstns="example" xmlns="example" xmlns:xs="http://www.w3.org/2001/XMLSchema" attributeFormDefault="unqualified" elementFormDefault="qualified">
           <xs:element name="an-element">
               <xs:complexType>
                   <xs:sequence minOccurs="0" maxOccurs="unbounded">
                       <xs:element name="another-element" nillable="true">
                           <xs:complexType>
                               <xs:simpleContent>
                                   <xs:extension base="xs:string">
                                       <xs:attribute name="an-attribute" form="unqualified" type="xs:boolean"/>
                                   </xs:extension>
                               </xs:simpleContent>
                           </xs:complexType>
                       </xs:element>
                   </xs:sequence>
               </xs:complexType>
           </xs:element>
       </xs:schema>
   End Function

End Module</lang>

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