From http://www.w3schools.com (Copyright Refsnes Data)

XML Validation

previous next

XML with correct syntax is "Well Formed" XML.

XML validated against a DTD is "Valid" XML.


Well Formed XML Documents

A "Well Formed" XML document has correct XML syntax.

The syntax rules were described in the previous chapters:

<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>


Valid XML Documents

A "Valid" XML document is a "Well Formed" XML document, which also conforms to the rules of a Document Type Definition (DTD):

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE note SYSTEM "Note.dtd">
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note> 

The DOCTYPE declaration in the example above, is a reference to an external DTD file. The content of the file is shown in the paragraph below.


XML DTD

The purpose of a DTD is to define the structure of an XML document. It defines the structure with a list of legal elements:

<!DOCTYPE note [
  <!ELEMENT note (to,from,heading,body)>
  <!ELEMENT to      (#PCDATA)>
  <!ELEMENT from    (#PCDATA)>
  <!ELEMENT heading (#PCDATA)>
  <!ELEMENT body    (#PCDATA)>
]>

If you want to study DTD, you will find our DTD tutorial on our homepage.


XML Schema 

W3C supports an XML based alternative to DTD called XML Schema:

<xs:element name="note">
<xs:complexType>
  <xs:sequence>
    <xs:element name="to"      type="xs:string"/>
    <xs:element name="from"    type="xs:string"/>
    <xs:element name="heading" type="xs:string"/>
    <xs:element name="body"    type="xs:string"/>
  </xs:sequence>
</xs:complexType>

</xs:element>

If you want to study XML Schema, you will find our Schema tutorial on our homepage.


A General XML Validator

To help you check the syntax of your XML files, we have created an XML validator to syntax-check your XML.

Please see the next chapter.


previous next

From http://www.w3schools.com (Copyright Refsnes Data)