XML What It Means To You

1
XML - What It Means To You

• William J. Bill McCalpin
• EDPP, CDIA, MIT, LIT
• Principal
• MHE

2
Introduction

• The Hegelian Dialectic

3
Thesis, Antithesis, Synthesis

• In the philosophy of Hegel, these words show the
  inevitable transition of thought, by
  contradiction and reconciliation, from
  an initial conviction to its opposite and then to
  a new, higher conception that involves but
  transcends both of them

4
The Hegelian Dialetic

• Thesis Most business have well-established,
  productive legacy systems
• Antithesis XML is springing forth everywhere
• Synthesis XML will be integrated with legacy
  systems - enhancing some processes, changing many
  others, and eliminating some altogether
• In short, XML will affect what you do

5
How To Relate XML to Everyman

• You might think that XML is too esoteric for most
  people to understand
• But XML is based on the basic human need
  exchanging information
• XML couples the communication skills we have used
  over the last several thousand years to modern,
  Internet technology
• So how can you understand it?

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Sex And The Single Pixel

• Or, How To Explain XML Through Human Relationships

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Men Are From MarsWomen Are From Venus

• Author John Gray has the best selling book
  describing the difficulties of communication
• Why would there be such difficulties?

8
Communication Difficulty 1

• In order for any communication to take place,
  both parties must share the same fundamental
  mechanism which carries information
• For example, in writing, if a boy and girl dont
  even share the same writing schemes, they cant
  possibly understand...

9
Chinese Characters vs Latin Alphabet

• I Love You

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Underlying Structure of XML

• Text characters
• Tags are delimited by lt and gt, i.e. ltxmlgt
• Ending tags have /, e.g., lt/xmlgt
• Parameters are indicated by double quotes, e.g.,
  ltPAPER track"Application"gt
• XML is a series of tags and data, e.g.,
  ltSTATEgtTexaslt/STATEgt

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Communication Difficulty 2

• Once both parties agree to the fundamental
  syntax, then both parties must next agree to the
  words to be used
• In the case of XML, how do both parties know that
  ltSTATEgt means a political subdivision and not one
  of gas,liquid,solid?

12
A Date Gone Bad

• One evening in the hotel lobby bar, two young
  Italian men spend a while talking to an
  attractive Venezuelan girl...and her aunt
• They spoke Italian and she spoke Spanish, but
  they communicated passably

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A Date Still Going Bad

• However, the aunt wanted to go up to her room
  with her niece
• The Italians wanted to take the young lady out
  dancing...
• So they asked her

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Oops

• What the boys said
• Vuoi andare con noi sta sera?

• What the young lady needed to hear
• Quisieras ir con nosotros esta tarde?

15
Miscommunication

• Even though Italian and Spanish use the same
  sounds, the same grammar, and have a common
  ancestry in Latin, some words are different
• Unfortunately, the most common words in both
  languages are likely to be the most different

16
The Cost Of Data Differences

• NASA lost a 125 million Mars orbiter because
  one engineering team used metric units while
  another used English units for a key spacecraft
  operation... CNN 9/30/99

17
XML Words

• HTML has a certain number of fixed tags -
  everyone knows what they are, but they cant be
  augmented
• In XML, everyone can make up their own tags to
  suit their needs - but how do we avoid a Tower of
  CyberBabel?

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Communication Difficulty 3

• Even when you agree to common tags, you still
  need to agree to a common understanding
• In XML, the Schema (now replacing the DTD)
  defines what tags are allowed to describe a
  particular collection of data
• For example, in the field of human relations,
  what is a date?

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One DTD For A Date

• A woman thinks
• Invitation - formal
• Dress-up - nicely
• Eat out dinner with wine at nice restaurant
• Entertainment see a movie
• Private moment good night kiss

• lt!DOCTYPE Date
• lt!ELEMENT Date (Invitation, Dress, Meal,
  Entertainment, Intimacy) gt
• lt!ELEMENT Invitation (PCDATA) gt
• lt!ELEMENT Dress (PCDATA) gt
• lt!ELEMENT Meal (PCDATA) gt
• lt!ELEMENT Entertainment (PCDATA) gt
• lt!ELEMENT Intimacy (PCDATA) gt

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A Womans View Of A Date

• ltdategt
• ltinvitationgtTelephone calllt/invitationgt
• ltdressgtLong dresslt/dressgt
• ltmealgt4-star restaurantlt/mealgt
• ltentertainmentgtthe theatrelt/entertainmentgt
• ltintimacygtA passionate, romantic kisslt/intimacygt
• lt/dategt

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Another DTD For A Date

• A man thinks
• Eat out six-pack
• Private moment necking

• lt!DOCTYPE Date
• lt!ELEMENT Date (Meal,Intimacy) gt
• lt!ELEMENT Meal (PCDATA) gt
• lt!ELEMENT Intimacy (PCDATA) gt

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A Mans View Of A Date

• ltdategt
• ltmealgtsix-pack of beerlt/mealgt
• ltintimacygtnecking
• lt/intimacygt
• lt/dategt

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When Men And Women Agree

• ltdategt
• ltinvitationgtTelephone calllt/invitationgt
• ltdressgtLong dresslt/dressgt
• ltmealgt4-star restaurantlt/mealgt
• ltentertainmentgtthe theatrelt/entertainmentgt
• ltintimacygtA passionate, romantic
  kisslt/intimacygt
• lt/dategt

• ltdategt
• ltinvitationgtHonking
• lt/invitationgt
• ltdressgtNot the shirt he changed the oil
  inlt/dressgt
• ltmealgtfood and beerlt/mealgt
• ltentertainmentgtrent a videolt/entertainmentgt
• ltintimacygtA passionate, romantic kiss while
  neckinglt/intimacygt
• lt/dategt

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Presentation

• In human relationships, its normal for someone
  to present themselves in the best light possible
• We try to minimize any deficiencies while
  maximizing our positive attributes
• Thus, we would like to present ourselves as

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Authors View
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Original Data
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XSL

• XSL - eXtended Style Language
• XSL is derived from CSS - Cascading Style Sheets
• XSL can enable the author to create one or many
  views of XML
• Since XSL can be separate from the XML object,
  the reader can apply the presentation information
  as well as the author

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Communication Difficulty 4

• When all we had was paper and film, the author
  alone controlled the presentation of the data
• One of the great advantages of electronic formats
  is that the presentation of data can now be put
  into the hands of the reader
• How can we describe this in the field of human
  relationships?

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Three Bachelors To Choose From

• Our contestant has to choose from 3 bachelors
• But if the information about the bachelors were
  on paper, then the information would be presented
  only one way

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How To Choose?

• But with XML (and other electronic formats like
  HTML), our contestant can view the information in
  different ways, to help her make her decision

• Bachelor List

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The Datamenttm
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The Datament

• Efforts to expand the meaning of document to
  include all manner of electronic formats have
  been unsuccessful
• Hence, we have invented the concept of the
  datamenttm, which is a organized collection of
  information in time which can be viewed by both
  human and machine

34
The Readers Of Dataments

• Because the datament is in XML, presentation
  information can be ignored and the data directly
  extracted from the appropriate tags
• Dataments can also carry one or more views of
  the data.
• One view should be the original static view
• Another view can allow the reader flexibility

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Why Multiple Views?

• Think of a 60,000 page phone bill - its
  impossible to make any sense of it without
  sorting, hiding, etc. like with a spreadsheet
• On the other hand, if one reader alters the view,
  then another reader might miss important
  information, hence there is a default view
• This default or author-centric view will also
  help satisfy regulatory authorities

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Communication Difficulty 5

• Without resorting to bars, how can people easily
  find compatible partners?
• Now think about all the classified ads you might
  have to pore through in order to find someone who
  interests you
• Fortunately, personals have a standard indexing
  method

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A Personal Ad

• DWF - divorced white female
• SBM - single black male
• WBFP - wood burning fireplace - oops
• This system works because there is a standard
  method of indexing personals
• If the authors of the classifieds made up their
  own indexes, think of the confusion

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Apples And Oranges

• nice DWM seeks girl who wants a good time
• cons w trvst in spc prog seeks swng aln to tk to
  their ldr

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Extending XML

• XML is not only a useful way to accurately
  describe people, er, information, but it can be
  use as the basis of many other standards
• For example, RDF stands for Resource
  Description Framework , that is, a framework for
  describing and interchanging metadata (i.e.,
  information about information).

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XML

• XML has a common underlying syntax
• Industries and groups can create XML tags which
  suit their needs
• XML enables both the author and the reader to
  control the presentation
• But lets digress...

41
What Is A Document?

• The American Heritage Dictionary defines a
  document as information in writing placed on a
  medium such as paper, often used as a record.
• Documents have been placed on clay tablets, gold
  leaf, animal skins, all types of paper,
  microfilm, optical storage, and so on

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Information And Presentation

• In every case, the document represents a
  fundamental union of information and presentation
• But presentation presumes that the primary
  audience for the document is a human being
• With the coming of the Internet, this is no
  longer the case

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The Curse Of Presentation

• Composition products require that you specify a
  printer, even before you know where the document
  will print

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Why Are Print, Image, And Presentation Formats
Incompatible?
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Printing And Imaging Formats

• Many printing formats AFP, Metacode, DJDE, XES
  (UDK), PostScript, PCL, etc.
• All formats use external resources like fonts,
  forms, graphics, etc., although sometimes
  inconsistently
• Most are escape-sequence based, some are formal
  data architectures, and some are almost
  programming languages

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Printing And Imaging Formats

• Many imaging formats - while most used CCITT
  Group 4 for image compression, most also had
  proprietary data wrappers
• Later systems adopted text-based formats such as
  PDF, although storing other print streams is not
  unknown
• Systems which store text-based formats must
  wrestle with resource issues

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Different Print Formats

• Why do printers have different formats? Because
  of physical constraints imposed by the hardware
• resources reduce the amount of data sent through
  pipeline to printer
• pages must be imaged in less than a fraction of a
  second
• complex graphics can be developed on the printer,
  but this needs a special language

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Different Imaging Formats

• Why do imaging systems have different formats
  because of physical constraints imposed by the
  hardware
• Mass storage was expensive
• Indexing schemes were too close to the
  application
• Text is avoided sometimes because of resource
  issues
• Interoperability with other products an issue

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Result

• In each case, data architecture decisions were
  made in order to enhance some aspect of
  legibility of the stored objects.
• If there were no requirement to present the
  information (to a human reader), then the
  requirement for custom data formats for each
  vendor would probably disappear!

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Universal Literacy

• Whos reading our documents?

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The Road To Universal Literacy

• First, only the few could read
• After the printing press, the many began to read
• Eventually, educational reforms brought the
  ability to read to all

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Literacy In The Internet Age

• Can there be a spread of literacy beyond all?
• How many webpages have you ever read?
• You will never be able to keep up with the Web
  alone
• There are already an estimated 98,685,000 host
  computers on the Internet (www.mids.org)

53
Intelligent Agents

• Just around the corner is software that will read
  the Web for us not search, but read
• So we have to spread literacy to an audience
  beyond all people, that is
• Does increased quality in presentation mean
  better computer literacy?

54
Noise On The Net

• Think of the average webpage
• three dimensional spinning objects
• marquees scrolling across the bottom
• multiple frames bookmarks
• audio
• These items are all designed to attract the eye
  your eye
• This does nothing for the machine reading the
  webpage

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Two Important Truths

• There are two important truths of the Internet
  era
• Documents which are read by humans need to be
  dynamic in their presentation
• Documents which are read by computers dont need
  any presentation information at all
• XML totally divorces presentation from
  information!

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What Have We Learned About XML?
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XML Summary

• XML uses tags to describe data
• ltstategtTexaslt/stategt
• Businesses and non-profits join together to build
  DTD/Schemas to describe data objects in their
  spaces
• lt?xml version"1.0" encoding"ISO-8859-1"?gt
• lt!DOCTYPE claim

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XML Summary

• An XML document contains information for a
  particular event or transaction which can be
  understand by both parties
• XML documents can be intended for two types of
  readers human and machine

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XML Summary

• XML documents intended for a machine do not
  require any presentation information
• XML dataments carry the information which
  enables both static (author-centric) and dynamic
  (reader-centric) presentations, using XSL

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What Will You Tell Your Boss?

• Well, this dude named Hegel met Drew Carey while
  speaking Spanish in an Italian bar when they met
  a transvestite space alien who was looking for a
  missing NASA satellite who told them that women
  were not either from Venus and that Mimi and
  Pierce Brosnan were on a date but each was
  reading different versions of the same menu
  because it was a datament in XML.

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Reference

• www.w3c.org - the official World Wide Web
  Consortium site (youll find links to the XML
  spec here)

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William J. Bill McCalpin

• EDPP, CDIA, MIT, LIT
• Principal, MHE
• 1400 Cheyenne Dr.
• Richardson, Texas 75080-3921
• 972-231-3660 (v) 972-690-4521 (f)
• mccalpin_at_mhe-consulting.com