XML validation

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[edit]

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.

 
#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;
}

Output, files used from the W3 Schools page :

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

C#[edit]

 
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);
	}
}

F#[edit]

Using an inline stylesheet:

open System.Xml
open System.Xml.Schema
open System.IO
 
let xml = @"<root>
<!--Start of schema-->
<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 of 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

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[edit]

Library: libxml2(Go)

This uses the w3schools test data linked to above.

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!")
}

Output:

Validation of shiporder.xml against shiporder.xsd successful!

Groovy[edit]

Translation of: Java

Solution:

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
    }
}

Test:

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'}"

Java[edit]

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;
		}
	}
}

Julia[edit]

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()

Kotlin[edit]

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.

// 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()
}

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[edit]

#!/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>5<b>foobar</b></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';
        }
    };
}

Output:

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

Python[edit]

#!/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>5<b>foobar</b></a>", parser)
	except lxml.etree.XMLSyntaxError as err:
		print (err)

Output:

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

Raku[edit]

(formerly Perl 6)

Translation of: Perl

 
# Reference: https://github.com/libxml-raku/LibXML-raku
 
use v6.d;
use LibXML;
use LibXML::Schema;
 
my $good_xml         = '<a>5</a>';
my $bad_xml          = '<a>5<b>foobar</b></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() ;
}

Output:

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

Scala[edit]

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
    }
  }
}

Sidef[edit]

Translation of: Perl

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>5<b>foobar</b></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)}"
}

Output:

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

Visual Basic .NET[edit]

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

Works with: .NET Core version 2.1

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

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]).

    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

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

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

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

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