XML Attributes

Attributes are the part of the Xml Elements. An Element contains multiple attributes. All are unique.
By the use of attributes we can add the information about the element.
XML attributes enhance the properties of the elements.

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Syntax

 <tag attibuteName=“attributeValue”>

<author bookType="Classical">
//else
<author bookType=‘Classical’>

Metadata should be stored as attribute and data should be stored as element.

<author bookType="Classical">
		<name>Venkat</name>
		<nationality>Indian</nationality>
</author>

Attributes are part of markup, while sub elements are part of the basic document contents.

In the below code bookType is an attribute

<author bookType="Classical">

In the below code bookType is an element

<author>
     <bootType>Classical</bookType>
</author>

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An attribute name must be appear once in the same start-tag or empty-element tag.
The value of the attributes within the quotation mark.
They used either single or double quotes.

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Attributes must contain a value. Some HTML coders does provide the attribute name without a value or it will equal true. This is not allowed in XML.
The values must not contain direct or indirect entity references to external entities.
Using an Attribute-List Declaration , an attribute must be declared in the Document Type Definition (DTD).

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Attributes doesn’t have multiple values but child elements can have multiple values.
Attributes cannot contain tree structure but child element can.
Attributes are not easily expandable. If you want to change in attribute's vales in future, it may be complicated.
Attributes cannot describe structure but child elements can.
Attributes are more difficult to be manipulated by program code.
Attributes values are not easy to test against a DTD, which is used to define the legal elements of an XML document.

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