8/4/2019 XML Bradsher 4-30-03

1/30

XMLeXtensible Markup Language

Charles A. Bradsher

Defense Technical Information Center

8/4/2019 XML Bradsher 4-30-03

2/30

eXtensible Markup Language

World Wide Web Consortium (W3C)

I.E. Legal XML QueryXML, Voice XML

Promotes business to business exchange (B2B)

Does not describe Formatting -Its about content

Uses any kind of information any kind of content

8/4/2019 XML Bradsher 4-30-03

3/30

8/4/2019 XML Bradsher 4-30-03

4/30

What is XML?

eXtensible - By applying Identifiers for

elements of information in a neutral way,

stored in a neutral form, independent ofsystems, devices and applications.

Markup - For adding information to adocument relating to its structure and/or

content.

8/4/2019 XML Bradsher 4-30-03

5/30

What is XML?

Language - A standard methodology with

formal syntax..However

XML is not a language but a toolkit fordeveloping or defining languages

A common syntax for expressing structure

in data

8/4/2019 XML Bradsher 4-30-03

6/30

How are SGML, HTML & XML

Related? Standard Generalized Markup Language

HTML is an application of SGML

XML is a subset of SGML

8/4/2019 XML Bradsher 4-30-03

7/30

Tags

Mrs. Air

Documents

1234 Concord Street Anytown

VA

45678

8/4/2019 XML Bradsher 4-30-03

8/30

Content

Mrs. Air

Documents

1234 Concord Street Anytown

VA

45678

8/4/2019 XML Bradsher 4-30-03

9/30

XML is Tags and Content

A Hierarchical Data RepresentationA Tree Structure Data

Representation

8/4/2019 XML Bradsher 4-30-03

10/30

Why Do We Need XML?

Interoperability

Info can be separated from the way it is

presented

Information can be presented in a variety of

ways depending on the device the end user

has.

8/4/2019 XML Bradsher 4-30-03

11/30

Why Do We Need XML?

Future Web developments hinge on the use

of XML W3C

Dependence on a single, inflexible document type

(HTML) which was being abused for task for which it

was never designed

SGML was too complex to fill the gap

8/4/2019 XML Bradsher 4-30-03

12/30

HTML vs. XML

Mrs. Air Documents

1234 Concord Street

Anytown, VA 45678

Mrs. Air Documents

1234 Concord Street Anytown, VA 45678

8/4/2019 XML Bradsher 4-30-03

13/30

HTML vs. XML

Mrs.

Air

Documents

1234 Concord Street Anytown

VA

45678

8/4/2019 XML Bradsher 4-30-03

14/30

HTML vs. XML

Mrs. Air Documents

1234 Concord Street

Anytown, VA 45678

8/4/2019 XML Bradsher 4-30-03

15/30

Mrs Air Documents

1234 Concord Street

Anytown, VA 45678

Mrs AirDocuments1234 Concord Street

Anytown, VA 45678

OMB 24 t

8/4/2019 XML Bradsher 4-30-03

16/30

OMBs 24 e-governmentInitiatives

8/4/2019 XML Bradsher 4-30-03

17/30

Why is XML Important?

Does not need a specific application

Perpetual preservation of Information

Could be future standardized mechanism forthe exchange of data

8/4/2019 XML Bradsher 4-30-03

18/30

How Does It Work?

XML Parser

XML Processor

XML does not provide an application

programming interface (API). ( Just passes

data to the application)

8/4/2019 XML Bradsher 4-30-03

19/30

What is a DTD?

DTD - Document Type Definition

A set of syntax rules for tags

What tags you can use in a document

Where the tags appear

Which tags can appear inside other tags

A set of constraints for documents

8/4/2019 XML Bradsher 4-30-03

20/30

DTD vs. Schema

DTD content models are closed and cant reflect the

openness XML supports.

DTD doesnt support data types beyond the 10primitive types.

It cant express rich data types allowed in XML

Schema

8/4/2019 XML Bradsher 4-30-03

21/30

Schema

Microsoft proposed an alternative approachto DTDs called schema

Like DTDs, schema provide the rules of adocument and indicate what tags areused.

Unlike DTDs, schema can define datatypes.

Designed to replace and amplify DTDs

8/4/2019 XML Bradsher 4-30-03

22/30

Schema

date)>

quantity CDATA #REQUIRED>

month CDATA #REQUIRED

year CDATA #REQUIRED >

8/4/2019 XML Bradsher 4-30-03

23/30

Schema

8/4/2019 XML Bradsher 4-30-03

24/30

8/4/2019 XML Bradsher 4-30-03

25/30

8/4/2019 XML Bradsher 4-30-03

26/30

Schema

8/4/2019 XML Bradsher 4-30-03

27/30

Schema

Example

A DTD might have a tag designated as

, but the content contained within thattag could be a number or a character string. A

schema would force you to enter a number.

DTD Schema

8/4/2019 XML Bradsher 4-30-03

28/30

Stylesheets

Provides hints and algorithms for rendering or

transforming the data in the XML document.

XSLT Extensible Stylesheet Language cantransform from one XML format to another

including HTML or plain text.

8/4/2019 XML Bradsher 4-30-03

29/30

For More XML Information:

For basic Information on XML:

http://www.xml.org/xml/resources_focus_b

eginnerguide.shtml W3C: http://www.w3.org/

Robin Cover's extensive list of online

reference material and links to software:http://xml.coverpages.org/

8/4/2019 XML Bradsher 4-30-03

30/30

QUESTIONS?