Ali Kamandi kamandi@ce.sharif.edu Fall 2007 Sharif University of - PowerPoint PPT Presentation

��� Ali Kamandi kamandi@ce.sharif.edu Fall 2007 Sharif University of Technology �

��� � e X tensible M arkup L anguage � Metalanguage - used to create other languages � Has become a universal data-exchange format �

���������������������� ���������������� <bibliography> ����������������������� <paper ID= "object-fusion"> <authors> <author>Y.Papakonstantinou</author> <author>S. Abiteboul</author> <author>H. Garcia-Molina</author> </authors> <fullPaper source="fusion"/> <title>Object Fusion in Mediator Systems</title> <booktitle>VLDB 96</booktitle> </paper> ��������������� ��������������� ��������������� ��������������� ������������ ������������ ������������ ������������ </bibliography> �

����������������� � Human-readable � Machine-readable (easy to parse) � Standard format for data interchange � Possible to validate � Extensible � can represent any data � can add new tags for new data formats � Hierarchical structure (nesting) �

�������������������������� Element element name Content <bibliography> <paper ID="object-fusion"> element <authors> <author>Y.Papakonstantinou</author> Empty <author>S. Abiteboul</author> <author>H. Garcia-Molina</author> Element </authors> <fullPaper source="fusion"/> <title>Object Fusion in Mediator Systems</title> <booktitle>VLDB 96</booktitle> </paper> Character content </bibliography> �

�������������!���� Attribute name <bibliography> Attribute Value <paper ID="object-fusion"> <authors> <author>Y.Papakonstantinou</author> <author>S. Abiteboul</author> <author>H. Garcia-Molina</author> </authors> <fullPaper source="fusion"/> <title>Object Fusion in Mediator Systems</title> <booktitle>VLDB 96</booktitle> </paper> </bibliography>

����#$���% � Tags properly nested � Tag names case-sensitive � All tags must be closed � or self-closing � <foo/> is the same as <foo></foo> � Attributes enclosed in quotes � Document consists of a single (root) element "

'���()��������*�+���� � Well-Formed: � Structure follows XML syntax rules � Valid: � Structure conforms to a DTD &

-.���+�*����/ •HTML confuses presentation with content •No Explicit Structure, Semantics <DT> Author <IMG SRC= "greenball.gif" >&nbsp; <A NAME="object-fusion"></A> Y.Papakonstantinou, S. Abiteboul, H. Garcia-Molina. <A HREF="http://www-cse.ucsd.edu/~yannis/papers/fusion.ps"> "ObjectFusion in Mediator Systems".</A> In <I>VLDB 96.</I> </DT> Title Conference ,

����������� XML HTML � Extensible set of tags � Fixed set of tags � Content orientated � Presentation oriented � Standard Data � No data validation infrastructure capabilities � Allows multiple output � Single presentation forms �0

�������#���1���������#������1�� � XML Document Type Definitions (DTDs): � XML Schema � defines structure and data types � allows developers to build their own libraries of interchanged data types ��

������������������������������� � An XML document may have an optional DTD. � A grammar for XML documents � Defines � which elements can contain which other elements � which attributes are allowed/required/permitted on which elements ��

������������ � Consider an XML document: <db><person><name>Alan</name> <age>42</age> <email>agb@usa.net </email> </person> <person>………</person> ………. </db> ��

������������ � DTD for it might be: <!DOCTYPE db [ <!ELEMENT db (person*)> <!ELEMENT person (name, age, email)> <!ELEMENT name (#PCDATA)> <!ELEMENT age (#PCDATA)> <!ELEMENT email (#PCDATA)> ]> ��

������������ Occurrence Indicator: Indicator Occurrence (no indicator) Required One and only one ? Optional None or one * Optional, None, one, or repeatable more + Required, One or more repeatable ��

��������2�1��������� Authors followed by optional fullpaper, Sequence of 0 or followed by title, more paper followed by booktitle <!element book paper*> <!element paper (authors, fullPaper?, title, booktitle)> <!element authors author+> Sequence of 1 or <!element author (#PCDATA)> more author Character content �

����#1����3��%����� �������������������������������������������������������� ��������������������� <type name="Order" > <element name="name" type="string" /> <element name="street" type="string" /> <element name="zip" type="integer" /> <...> <attribute name="orderDate" type="date" /> </type> �"

����#1����3��%����� ������������������������������������������������������ <type name="personName"> <element name="title" minOccurs="0"/> <element name="forename" minOccurs="0" maxOccurs="*"/> <element name="surname"/> </type> <type name="extendedName" source="personName" derivedBy="extension"> <element name="generation" minOccurs="0"/> </type> <type name="simpleName" source="personName" derivedBy="restriction"> <restrictions> <element name="title" maxOccurs=“1"/> <element name="forename" minOccurs="1" maxOccurs="1"/> </restrictions> </type> �&