Title: SGML
1SGML
- 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
2HTML
- 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)
3W3C
- 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
4W3C 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
5What 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.
6Cascading 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
7Cascading 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
8eXtensible 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
9eXtensible 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
10eXtensible 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
11eXtensible 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 !
12eXtensible 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
13eXtensible 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.
14eXtensible 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.
15eXtensible Markup Language(XML) continued
16eXtensible Markup Language(XML) continued
17eXtensible 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
18eXtensible 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
19eXtensible 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
20eXtensible 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
21MathML
- 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
22VoiceXML
- 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.