XML

1
XML

• A Language Presentation

2
Outline

• 1. Introduction
• 2. XML
• 2.1 Background
• 2.2 Structure
• 2.3 Advantages
• 3. Related Technologies
• 3.1 DTD
• 3.2 Schemas and Data Types
• 3.3 XSL, XQL and CSS
• 3.4 XLink and XPointer
• 4. Conclusions
• 5. Questions

3
1. Introduction

• XML eXtensiable Markup Language
• Special way of transferring data
• Plain text with meaningful structure
• Platform and application independent
• Many technologies built on top of XML

4
2. XML

• A sample XML document

5
2.1 Background

• Created by the SGML editorial Review Board in
  1996
• Specific design goals
• Subset of the Standard Generalized Markup
  Language or SGML
• Looks similar to HTML

6
2.2 Structure

• Uses storage units called entities, such as
  elements and attributes
• Tree layout root, parents and children
• All entities are defined by explicit markup
• Strict rules for defining syntax

7
2.2 continued

• Unlike HTML, XML elements and attributes are
  defined by the author
• Namespaces help avoid name collisions
• Usually, authors web page is used
• Namespaces can be applied to specific parts of
  the document and not others

8
2.3 Advantages

• Data is independent of applications
• Can be interpreted in anyway the author intends
• The way the data is viewed/styled is independent
• An XML document is self describing

9
3. Related Technologies

• How is XML used by or with applications?

10
3.1 Document Type Definition (DTD)

• Defines structure
• Allows parsers and applications to read the
  document
• Can be with the document or in an external file
• DTDs are an important part of XML documents

11
3.2 Schemas and Data Types

• Alternate to DTDs
• Required to define data for applications
• Can define data types
• Scope exists
• Inheritance and sub-classing

12
3.2 continued

• A sample Schema

13
3.3 XSL, XQL and CSS

• Define how the data is displayed
• Can filter or sort data
• Used to manipulate, create, control, or manage
  document and data
• Transformations into HTML or other XML documents

14
3.4 XLink and XPointer

• Creates links to other documents
• Creates links to specific parts of documents or
  other resources
• Can be used to create documents very similar to
  HTML
• Vital aid due to the lack of predefined elements

15
4. Conclusions

• Simple platform and application independent way
  of transferring data
• General purpose, is it a language?
• Many related and important technologies
• Gives author/interpreter complete control
• Appearing everywhere, have you seen it?

16
5. Questions?