XML Schema includes another way of documenting schema components by using the xs:annotation and xs:documentation elements.
These elements can only appear at certain places within a schema, typically as the first element after a main 'keyword' such as xs:schema , xs:element , xs:attribute , xs:complexType , and xs:simpleType. Note that we have only included a single global element here.
A global element corresponds to an xs:element definition that is a child but not a grandchild etc. This is because any element defined by a global element is allowed to be the top-level element in a valid XML instance. Normally it is desired to have only one possible top-level element in an XML instance, and so this constraint is imposed in the schema by only having one global element definition.
Having selected an editor, follow these steps to create your first schema: If the outer most element of your XML instance is to be a sequence as described in 9. TODO: add the type TODO: Add additional elements as required TODO: Add additional referenced type definitions Add additional element definitions to the ' MyGlobalElementType ' as required. Add additional types to the referenced types section as required.
Save the schema to a file. Compile the schema using LMX. Integrate the generated code into your project! Thanks for letting us know! Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. There was an error. Tell us why! More from Lifewire. Your Privacy Rights. To change or withdraw your consent choices for Lifewire. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page.
These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification. Earlier, when we started looking at elements, we said you could define your own types instead of using one of the standard types such as xs:string or xs:integer, and that is exactly what were now doing.
Hopefully, the advantages are obvious. Instead of having to define Address twice once for Customer and once for Supplier we now have a single definition.
This makes maintenance simpler, i. An attribute provides extra information within an element. Attributes have name and type properties and are defined within an XSD as follows:.
An Attribute can appear 0 or 1 times within a given element in the XML document. Attributes are either optional or mandatory by default they are optional. The "use" property in the XSD definition is used to specify if the attribute is optional or mandatory. An attribute is specified within a xs:complexType, the type information for the attribute comes from a xs:simpleType either defined inline or via a reference to a built in or user defined xs:simpleType definition.
The Type information describes the data the attribute can contain in the XML document, i. Attributes can also be specified globally and then referenced but more about this later.
The default and fixed attributes can be specified within the XSD attribute specification in the same way as they are for elements. So far we have seen how an element can contain data, other elements and attributes. Elements can also contain a combination of all of these. You can also mix elements and data. You can specify this in the XSD schema by setting the mixed property.
The restriction element is more often used to apply restrictions to elements. Look at the following lines from the schema above:. This indicates that the value of the element or attribute must be a string, it must be exactly six characters in a row, and those characters must be a number from 0 to 9.
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Examples might be simplified to improve reading and learning.
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