SGML

1
SGML

• SGML stands for
• Standard Generalized Markup Language
• In 1960, three IBM employees were exploring a way
  to interchange documents of different file
  formats
• Solution System-independent common format
• Use a mark-up language
• How?
• Identify a structure of a document
• In 1974, IBM employee found a way to analyze the
  structure and syntax of a document
• i.e. parser
• In 1986, SGML was adopted as an international
  standard

2
HTML

• In 1989, Tim Berners-Lee began exploring a way to
  develop a technology for sharing information
  using hyperlinked text documents
• He based this technology on SGML and called it
  HyperText Markup Language (HTML)

3
W3C

• October 94 Tim Berners-Lee founded World Wide
  Web Consortium (W3C)
• Aim develop interoperable technologies
• Make the web universally accessible regardless of
  language, culture, etc
• W3C serves as a standardization organization.
• Web technologies standardized by W3C are called
  Recommendations
• Current Recommendations include
• HTML, CSS, XML, etc

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W3C continued

• What are recommendations?
• They are not an actual software
• Documents that specify the role, syntax, rules,
  etc.., of a technology (i.e. HTML)
• W3C is inspired by
• MIT (USA)
• INRIA (France),
• Keio University (Japan), and
• other members

5
What is DTD?

• The document type definition (DTD) is the method
  used to define all markup languages.
• DTD specifies the syntax (grammatical structure)
  of a web page
• While HTML predefines set of tags guaranteed to
  be understood and displayed in a uniform fashion
  in a web browser, XML allows the document creator
  to define any set of tags he or she wishes to.
• This set of tags is grouped into a set of rules
  known as the Document Type Definition.

6
Cascading Style Sheets (CSS)

• CSS enables you to specify the style of your page
  elements
• i.e. spacing, margins, mouse-over colors, etc
• separately from the structure of a document
• Advantage
• Separate structure from presentation
• Manageability
• Changing style of a document is more dynamic

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Cascading Style Sheets (CSS)continued

• Declaring styles in a document
• Inline Style
• within an element (i.e. HTML elements)
• Style Element
• through style element (i.e. apply to all elements
  within a document)
• External document
• Linking an external style sheet

8
eXtensible Markup Language(XML)

• XML is a technology that allows developers to
  describe data of any type in a structured manner
• XML, unlike HTML, allows authors to describe data
  more precisely by creating new tags.
• XML serves as basis for creation of other markup
  languages (i.e. WSDL) used for describing data

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eXtensible Markup Language(XML) continued

• Sample XML document i.e. books.xml
• lt?xml version "1.0"?gt
• ltBooksgt
• ltBookgt
• ltISBNgt0596007647lt/ISBNgt
• ltAuthorgtElliotte Rusty Harold, W. Scott Means
  lt/Authorgt
• ltTitlegtXML in a Nutshell, Third Edition lt/Titlegt
• ltPublishergtO'Reilly Media, Inclt/Publishergt
• lt/Bookgt
• lt/Booksgt

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eXtensible Markup Language(XML) continued

• lt?xml version "1.0"?gt
• ltBooksgt
• ltBookgt
• ltISBNgt0596007647lt/ISBNgt
• ltAuthorgtElliotte Rusty Harold, W. Scott Means
  lt/Authorgt
• ltTitlegtXML in a Nutshell, Third Edition lt/Titlegt
• ltPublishergtO'Reilly Media, Inclt/Publishergt
• ltEdition ver2/gt
• lt/Bookgt
• lt/Booksgt

root element
opening tag
empty tag
closing tag
attribute value
attribute
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eXtensible Markup Language(XML) continued

• A software called XML Parser is required for
  processing XML documents.
• XML Parser
• Reads XML document
• Checks the syntax
• Reports any errors
• XML is case sensitive !

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eXtensible Markup Language(XML) continued

• For accessing XML documents, parsers can support
• Document Object Model (DOM)
• Builds a tree structure containing the XML
  documents data in memory
• Simple API for XML (SAX)
• When text, comments etc.. are processed, the SAX
  generates events in the form of data
• i.e. notifications to the applications

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eXtensible Markup Language(XML) continued

• Parsing with MSXML
• When a document is loaded into IE, the document
  is processed and parsed by msxml.
• If the document is free of errors, the parser
  makes the documents data available to the
  application (i.e. IE).
• The application can render and format the data
  and performs other processing.

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eXtensible Markup Language(XML) continued

• When books.xml is loaded into IE, the msxml
  parses the XML document and makes the data
  available.
• A stylesheet that formats and colors the markup
  almost identically to the original document is
  used.

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eXtensible Markup Language(XML) continued

• IE output

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eXtensible Markup Language(XML) continued

• Firefox output

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eXtensible Markup Language(XML) continued

• Markup
• ltimg srctest.gifgt
• In HTML, this code is correct, but in XML it is
  not. The ending tag must also be supplied
• ltimg srctest.gifgtlt/imggt
• This type of element is called empty element
  because it does not contain any content (i.e.
  data between the tags). Alternatively, empty tags
  can be written as
• ltimg srctest.gif/gt
• forward slash for termination

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eXtensible Markup Language(XML) continued

• Elements define structure
• An element may or may not contain content
• Attributes describe elements
• i.e. ltimg src width heightgt
• An element may have zero, one, or more
  attributes.
• Attributes are placed within the elements start
  tag
• Values for attributes are enclosed in quotes
• Example
• ltBookInfo authorSome Name isbn 1223232
  publisherOReillygt

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eXtensible Markup Language(XML) continued

• CDATA Sections
• These are sections that can contain text,
  reserved characters, and whitespace characters.
• Character data in the CDATA section are not
  processed by the XML parser.
• Common use for CDATA is JavaScript, VBScript,
  etc

Whitespace characters are Spaces, tabs, and
carriage returns are characters commonly
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eXtensible Markup Language(XML) continued

• Namespaces
• Since authors have the ability to create their
  own tags, a collision can occur
• Collision two different elements having the same
  name
• Namespaces provides authors with the means to
  prevent collisions

21
MathML

• Presenting mathematical expressions and equations
  in web documents is usually difficult
• Most systems support only the basic symbols for
  operators such as ,-,, /
• MathML, the Math Markup Language, meets the needs
  of a broad set of users including scientists,
  teachers, publishing industry, etc
• MathML allows you to create and manipulate
  mathematical expressions

22
VoiceXML

• VoiceXML is used to define voice catalogs
• i.e. interactive phone-based banking system for
  accessing account
• i.e. Registering for services
• i.e. Checking your balance
• VoiceXML uses interactive voice systems that read
  content to you loud over the phone.
• It relies on infrastructure like the Internet
  Interactive Voice Response (IVR) devices, and
  VoiceXML gateways to deliver content.