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Advanced Multimedia Tech. eXtensible Mark-up Language Part I

Advanced Multimedia Tech. eXtensible Mark-up Language Part I. Prof. A. Taleb-Bendiab Room 605 a.talebbendiab@livjm.ac.uk http://www.cms.livjm.ac.uk/taleb/lectures/cmssem013. So far …. Dr. R. Pereira Module Workplan Schedule. In this Session…. Brief introduction to XML Definitions

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Advanced Multimedia Tech. eXtensible Mark-up Language Part I

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  1. Advanced Multimedia Tech.eXtensible Mark-up Language Part I Prof. A. Taleb-Bendiab Room 605 a.talebbendiab@livjm.ac.uk http://www.cms.livjm.ac.uk/taleb/lectures/cmssem013

  2. So far … • Dr. R. Pereira Module Workplan Schedule

  3. In this Session… • Brief introduction to XML • Definitions • Examples • XML and DTD • Web applications • Tutorial session in Lab • Exercise • This lecture is based on Mr. Mark Allen Lecture Notes.

  4. Web Page Example

  5. HTML Code <html > <head> <meta name="GENERATOR" content="Microsoft FrontPage 4.0"> <meta name="Microsoft Theme" content="global 101, default"> <meta name="Microsoft Border" content="tlrb, default"> <title>Home Page</title> </head> <body background="../../_themes/global/glotextb.gif" bgcolor="#FFFFCC" text="#510000" link="#999900" vlink="#CC9966" alink="#990066"> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr><td><font face="Arial, Helvetica"> <p align="center"><br> <font size="4" face="Arial">Student Learning Space</font></p> <p align="center"><a href="../Default.htm">Home</a>&nbsp;&nbsp; <a href="../cmssem011/Module%20specification.doc">Module <a href="http://www.cms.livjm.ac.uk/markallen/multi-media.htm">Tutorials</a> <a href="../cmssem011/indicative_references.htm"> Reading List</a></p> <p align="left"><font size="4">Contemporary issues in IT: Distributed Applications and E-Commerce <em>CMSCB3005</em><font size="4" face="Arial">&nbsp;</font></font></p> </html>

  6. Associated XML Code <?xml version="1.0"?>> <?xml-stylesheet type="text/xsl" href="..\xsl\ENR-change-table.xsl"?> <!DOCTYPE Components SYSTEM "Project6.dtd"> <head> <meta name="Microsoft Theme" content="global 101, default"> <title> Student Learning Space </title> </head> <body> <main> <page type=“html” href="../Default.htm"> <headings> <heading 1 href="../cmssem011/Module%20specification.doc"> <heading 2 href="http://www.cms.livjm.ac.uk/markallen/multi-media.htm"> <heading 3 href="../cmssem011/indicative_references.htm"> </headings> </main> </body> </xml>

  7. What is XML? • XML is • an eXtensible Markup Language for describing both structured and unstructured information, which could be usedon the web. • XML documents containing structured information including; • Content: words, pictures (vector graphics), e-commerce transactions, mathematical equations, object meta-data, server APIs, and other XML documents. • XML is a meta-language for defining other markup languages not like HTML or SGML • Unlike Html or SGML it provides; • extensible tag semantics • a facility to define tags and the structural relationships between them. • All of the semantics of an XML document will either be defined by the applications that process them or by stylesheets.

  8. XML System • An XML system consists of • XML Document • The content or information • Document Type Definition (DTD) • The structural definition • Defines the logical structure of the document • A Tree • XML Parser • Checks document for correctness. • Checks the document conforms to the DTD • XML Application • A program that does something useful with XML documents

  9. An Example of XML Document <?xml version = "1.0" ?> <!DOCTYPE RESTAURANTS SYSTEM "restaurant.dtd"> <?xml-stylesheet type="text/xsl" href="srt_restaurant.xsl"?> <!-- Define XSL Stylesheet to be used with current XML Document --> <RESTAURANTS> <RESTAURANT FOOD_GENRE="Chinese"> <NAME>Yin Yang</NAME> <FOOD_RATING>4</FOOD_RATING> <AMBIANCE_RATING>2</AMBIANCE_RATING> <AVERAGE_MEAL_COST>$6</AVERAGE_MEAL_COST> <REVIEW>Great food, but better to order take out than to eat in.</REVIEW> </RESTAURANT> <RESTAURANT FOOD_GENRE="Italian"> <NAME>Little Italy</NAME> <FOOD_RATING>3</FOOD_RATING> <AMBIANCE_RATING>4</AMBIANCE_RATING> <AVERAGE_MEAL_COST>$8</AVERAGE_MEAL_COST> <REVIEW>Romantic setting, great place to go with a date</REVIEW> </RESTAURANT> </RESTAURANTS>

  10. How Is XML Defined? • XML document is defined by a number of related specifications: • Extensible Markup Language (XML) 1.0 • Defining the syntax of XML. • XML Pointer Language (XPointer) and XML Linking Language (XLink) • Defining a standard way to represent links between resources. In addition to simple links, like HTML's <A> tag, XML has mechanisms for links between multiple resources and links between read-only resources. • XPointer describes how to address a resource, • XLink describes how to associate two or more resources. • Extensible Style Language (XSL) • Defines the standard stylesheet language for XML. • XQL -- Defines a standard query language for XML. • XUL -- Defines a standard user-interface language for XML.

  11. XML Markup #1 • Six kinds of markup are used in XML documents: • 1. Elements -- Delimited by angle brackets, most elements identify the nature of the content they surround. • It begins with a start-tag, <element>, and ends with an end-tag, </element>. • Attributes -- Attributes are name-value pairs that occur inside start-tags after the element name. • <div class="preface">is a div element with the attribute class having the value preface. • 2. entity references -- introduce markup into a document, some characters have been reserved to identify the start of markup. • entities are used to represent these special characters. Entities are also used to refer to often repeated or varying text and to include the content of external files. • Entity references begin with the ampersand and end with a semicolon.

  12. XML Markup #2 • For example, the lt entity inserts a literal < into a document. So the string <element> can be represented in an XML document as &lt;element>. • A special form of entity reference, called a character reference, can be used to insert arbitrary Unicode characters into your document. This is a mechanism for inserting characters that cannot be typed directly on your keyboard. • 3. Comments -- begin with <!-- and end with -->. • Comments can contain any data except the literal string. • 4. processing instructions(PIs) -- are an escape hatch to provide information to an application. • Processing instructions have the form: <?name pidata?>. The name, called the PI target, identifies the PI to the application. • 5. CDATA Sections – to instruct the parser to ignore most markup characters. • to prevent xml parser from evaluating a CDATA. • <![CDATA[ *p = &q; b = (i <= 3); ]]> 

  13. XML Markup #3 • Between the start of the section, <![CDATA[ and the end of the section, ]]>, all character data is passed directly to the application, without interpretation. • The only string that cannot occur in a CDATA section is ]]>. • 6. Document Type Declarations • XML allows you to create your own tag names. • DTD enables document to communicate their meta-information to the parser including; • allowed sequence and nesting of tags, • attribute values and their types • defaults, the names of external files that may be referenced • formats of some external (non-XML) data that may be referenced, • the entities that may be encountered.

  14. XML and DTD Syntax XML Syntax DTD Syntax • Elements & nesting • Attributes • XML document • Comments • Unicode • CDATA • Namespace • Processing Instructions • Elements declaration • Content model • Attribute declaration • Entities • - general/parameter • - internal/external • - parsed/unparsed • Notations => Parser sees meaningless element names => Parser differentiates parent-child structure => Application provides semantics

  15. DTD Declaration Examples • A set of rules • define the structure of a document • The DTD can be declared internally or externally <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE group SYSTEM "group.dtd"> <group> </group> <?xml version = "1.0" ?> <!DOCTYPE test [ <!ELEMENT name (#PCDATA)> <!ATTLIST name rating CDATA> ]> <test> </test>

  16. DTD Syntax #1 • <!ELEMENT name (content_model)> • <!ATTLIST name gender CDATA > • <!ENTITY icon SYSTEM “icon.jpg”> • ELEMENT SYNTAX • <!ELEMENT name (content_rule)> • <!ELEMENT name (a,b,c)> • <!ELEMENT name (a|b|c)> • <!ELEMENT name (#PCDATA)> • <!ELEMENT name EMPTY> • <!ELEMENT name ANY> • <!ELEMENT name (a,b?,c+,d*)> • <!ELEMENT name (a|b|c)*>

  17. DTD Syntax #2 • ATTRIBUTE SYNTAX #1 • <!ATTLIST e_name name definitions> • <!ATTLIST e_name name CDATA default> • <!ATTLIST e_name name type (a|b|c) default> • <!ATTLIST e_name name ENTITY default> • <!ATTLIST e_name name NMTOKEN default> • <!ATTLIST e_name name ID default> • Attribute Defaults • #REQUIRED -- Value must be supplied • #IMPLIED -- Value can be left blank • #FIXED -- Value is fixed • Default value supplied.

  18. DTD Syntax #3 • ATTRIBUTE SYNTAX #2 • <!ATTLIST car number CDATA #REQUIRED> • <!ATTLIST person gender CDATA #IMPLIED> • <!ATTLIST person mood CDATA #FIXED “Happy”> • <!ATTLIST car colour (red|green|blue) “green”> • <!ATTLIST car colour CDATA “green”> • ENTITIES • Text Substitution • <!ENTITY author “Mark” • &author; • Reference to external entity. • <!ENTITY picture SYSTEM “mark.jpg”> • &picture;

  19. DTD Syntax #4 • Processing Instructions • Specific to an Application • <?xml version =“1.0”?> • <?processor specific_instruction=“value”?>

  20. DTD Example <!ELEMENT RESTAURANTS (RESTAURANT*)> <!ELEMENT RESTAURANT (NAME,FOOD_RATING,AMBIANCE_RATING,AVERAGE_MEAL_COST,REVIEW)> <!ATTLIST RESTAURANT FOOD_GENRE CDATA #REQUIRED> <!ELEMENT NAME (#PCDATA)> <!ELEMENT FOOD_RATING (#PCDATA)> <!ELEMENT AMBIANCE_RATING (#PCDATA)> <!ELEMENT AVERAGE_MEAL_COST (#PCDATA)> <!ELEMENT REVIEW (#PCDATA)>

  21. Validation • Two categories of XML documents: • Well-formed Documents • it obeys the syntax and the grammar of XML documents. • A document that includes sequences of markup characters that cannot be parsed or are invalid cannot be well-formed. • not well-formed document -- is not XML document. • Checked against XML syntax • well-formed and valid: • well-formed document is valid only if it contains a proper document type declaration and if the document obeys the constraints of that declaration. • Checked against DTD

  22. XML Document Parsing DTD No Yes Yes XML Well- DTD Valid? Document formed? Required? No No Structural XML Non-conformance Syntax Error Message Error Message Stop Processing / Edit XML and/or DTD / Re-initiate Parsing Well-formed XML XML Document Further processing of Well-formed & Valid XML PARSER

  23. XML Processing and Rendering DTD SAX Application Script/Program PARSER DOM XML API XML Document XSL XSL-based Processing layer Other Markup Languages WML Scalable Vector Graphics (SVG) RDF, XMI Etc. RTF (MS Word) PDF HTML Output Output • XML Document/DTD/Parser • Document Object Model (DOM) • Script/Programming (manipulation of objects) • XSL (render ready transformation) • Browser/Display Application • (rendering)

  24. Why XML is so popular? Web Layer Request Data source Response

  25. What use is it? • Standardised Data Communication. • Multiple views of the same data. • Client and server-side processing. • Improved Searching. • Scalability and open standards. • Compressibility. • For defining other mark-up languages

  26. Example Applications #1 • SpeechML • MathML • MathML http://www.w3.org/TR/REC-MathML/ • SMIL • Synchronised Multimedia Integration Language • SMIL http://www.w3.org/TR/REC-smil/ • SAML • Security Assertion Markup Language • WSDL • Web Services Description Languages • Useful Links includes • XML http://www.w3.org/TR/REC-xml/ • XSL http://www.w3.org/TR/WD-xsl/

  27. Example Applications #2 • XML in Server-Side Technology for thin client architecture • Applications Integration

  28. Combining Java and XML Communication Fire Fighter RDBMS Login System Mobilisation tool C&C Operator Search Engine Admin tools System Admin. Reporting tools

  29. Target System Architecture

  30. Next Session… • Introduction to eXtensible Styling Language • Definitions • Examples • Tutorial session • Exercise

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