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2017, Fall Pusan National University Ki-Joune Li
XML 2017, Fall Pusan National University Ki-Joune Li
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XML – Basic Concepts XML (eXtensible Markup Language
A variation of HTML (Not only presentation but also description) A standard language for contents Designed to store and transport data Self-Descriptive using Tags (like HTML) W3C standard Syntax is very similar with HTML <?xml version="1.0" encoding="UTF-8"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
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XML, HTML, Databases, and Java Instances
System A Representing and Storing Data Display to Users via Web Browser Databases HTML document Conversion To HTML Conversion To DB XML document System B Exchange Data XML Serialization Instances from Java Class Objects from C++ Class
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Nested – Tree Structure
Example <?xml version="1.0" encoding="UTF-8"?> <breakfast_menu> <food> <name>Strawberry Belgian Waffles</name> <price>$7.95</price> <description> Light Belgian waffles covered with strawberries and whipped cream </description> <calories>900</calories> </food> <food> <name>French Toast</name> <price>$4.50</price> <description> Thick slices made from our homemade sourdough bread </description> <calories>600</calories> </food> </breakfast_menu> Element Nested – Tree Structure
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Syntax - basics Very simple and logical XML Prolog – like HTML Header
Data with Tags Must Contain one Root Element Open Close Tag (case sensitive) May be nested No predefined tags Attribute of Elements XML Prolog – like HTML Header <note> <date> <year>2008</year> <month>01</month> <day>10</day> </date> <to>Tove</to> <from>Jani</from> </note> <root> <child> <subchild>.....</subchild> </child> </root> <note date="12/11/2007"> <to>Tove</to> <from>Jani</from> </note> <?xml version="1.0" encoding="UTF-8"?>
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Syntax - Elements Element: An XML element
everything from (including) the element's start tag to (including) the element's end tag. Contains text attributes other elements or a mix of the above <bookstore> <book category="children"> <title>Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="web"> <title>Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> </bookstore>
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One Solution: use prefix
Name Conflicts Tags in XML – User-defined may cause conflicts <table> <tr> <td>Apples</td> <td>Bananas</td> </tr> </table> <table> <name>African Coffee Table</name> <width>80</width> <length>120</length> </table> XML XML (HTML) <h:table> <h:tr> <h:td>Apples</h:td> <h:td>Bananas</h:td> </h:tr> </h:table> <f:table> <f:name>African Coffee Table</f:name> <f:width>80</f:width> <f:length>120</f:length> </f:table> One Solution: use prefix
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Name Conflicts – Namespaces (xmlns)
When using prefixes, a namespace for the prefix must be defined. The namespace can be defined by an xmlns attribute in the start tag The namespace declaration has the following syntax. xmlns:prefix="URI". <root xmlns:h=" xmlns:f=" <h:table> <h:tr> <h:td>Apples</h:td> <h:td>Bananas</h:td> </h:tr> </h:table> <f:table> <f:name>African Coffee Table</f:name> <f:width>80</f:width> <f:length>120</f:length> </f:table> </root> Another Solution: xmlns
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XML Schema Definition of XML Structures that are frequently used
It is a XML document Like class definition <?xml version="1.0"?> <xs:schema xmlns:xs=" <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> </xs:schema> Complex Element Type Simple Element Type Instance document <?xml version="1.0"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
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Xlink XLink is used to create hyperlinks in XML documents
no browser support but can be converted to <a href=“…”> of HTML <?xml version="1.0" encoding="UTF-8"?> <bookstore xmlns:xlink=" <book title="Harry Potter"> <description xlink:type="simple“ xlink:href="/images/HPotter.gif" xlink:show="new"> As his fifth year at Hogwarts School of Witchcraft and </description> </book> <book title="XQuery Kick Start"> <description xlink:type="simple“ xlink:href="/images/XQuery.gif" xlink:show="new"> XQuery Kick Start delivers a concise introduction </description> </book> </bookstore>
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