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Declare a Schema File I

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Declare a Schema File

• A collection of semantic validation rules designed to constrain XML data values

• Reasons to choose Schema over DTDs

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Declare a Schema File

• The syntax of schema

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An Example

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Schema

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Add a Comment

• Comment cannot appear in

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Contain Other Elements

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Contain Other Elements

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Contain Other Elements

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Contain Other Elements

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Declare One-Time Element

• A given element is associate with one – and only one – value at runtime

• Also called a required element

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Declare One-Time Element

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Declare One-Time Element

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Declare Optional Elements

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Declare Optional Elements

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Declare Repeatable Elements

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Declare Repeatable Elements

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Contain Character Data

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Contain Character Data

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Contain Character Data

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Contain Character Data

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Declare Empty Element

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Declare Empty Element

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Declare Empty Element

• Conceptually, elements represent data, while attributes represent metadata, or “data about data.”

• In other word, elements model essential information; attributes model descriptive information.

• Associating attributes with an element defined as empty is fairly common practice.

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Declare Empty Element

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Contain Mixed Value

• Declare a schema validation rule that allow an XML element to contain both– Character data– Other predefined elements

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Contain Mixed Value

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Contain Mixed Value

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