XSD - The <schema> Element
The <schema> element is the root element of every XML Schema.
The <schema> Element
The <schema> element is the root element of every XML Schema:
<?xml version="1.0"?>
<xs:schema>
...
...
</xs:schema>
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The <schema> element may contain some attributes. A schema declaration often looks
something like this:
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.w3schools.com"
xmlns="http://www.w3schools.com"
elementFormDefault="qualified">
...
...
</xs:schema>
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The following fragment:
xmlns:xs="http://www.w3.org/2001/XMLSchema"
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indicates that the elements and data types used in the schema come from the "http://www.w3.org/2001/XMLSchema"
namespace. It also specifies that the elements and data types that come from the
"http://www.w3.org/2001/XMLSchema" namespace should be prefixed with
xs:
This fragment:
targetNamespace="http://www.w3schools.com"
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indicates that the elements defined by this schema (note, to, from, heading,
body.) come from the "http://www.w3schools.com" namespace.
This fragment:
xmlns="http://www.w3schools.com"
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indicates that the default namespace is "http://www.w3schools.com".
This fragment:
elementFormDefault="qualified"
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indicates that any elements used by the XML instance document which were
declared in this schema must be namespace qualified.
Referencing a Schema in an XML Document
This XML document has a reference to an XML Schema:
<?xml version="1.0"?>
<note xmlns="http://www.w3schools.com"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3schools.com note.xsd">
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
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The following fragment:
xmlns="http://www.w3schools.com"
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specifies the default namespace declaration. This declaration tells the
schema-validator that all the elements used in this XML document are declared in
the "http://www.w3schools.com" namespace.
Once you have the XML Schema Instance namespace available:
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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you can use the schemaLocation attribute. This attribute has two values. The first value is the namespace
to use.
The second value is the location of the XML schema to use for that
namespace:
xsi:schemaLocation="http://www.w3schools.com note.xsd"
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