Session Date: April 17, 2006

1
Internet Supply Chain Management ECT 481
Spring 2006
Session Number 4

• Session Date April 17, 2006
• Session Outline
• Midterm Exam Highlights
• Project Info
• Session Topics XML
• XML Defined
• XML as a Content Development Tool

2
Administrative Items

• Midterm Exam Highlights
• Project Teams Project Instructions

3
XML - Mission Critical Terminology

• XML Defined
• A markup language for documents containing
  structured information.
• XML is really a meta-language for describing
  markup languages. XML provides a facility to
  define tags and the structural relationships
  between them.

4
XML Mission Critical Terminology (continued)

• Elements define common components of an XML
  document.
• Elements fall into three categories.
• those that define the structure of a document.
• those that specify the content of a document.
• those that apply formats to parts of documents.
• Attributes - is a specified behavioral
  characteristic of an element.
• Entity a named segment or piece of information
  that can range from a single character to an
  entire book consisting of packaged as one file.

5
XML Mission Critical Terminology (continued)

• Markup - commands that define attributes, such
  as formats enhancements, and describe the
  documents.
• Processing Instructions - part of the markup
  that tells the XML processor or browser how to
  handle an upcoming statement (or statements).
• Style Sheets a set of instructions with which
  document is formatted.
• Document Type Declaration a declaration in an
  XML document that points to or refers to a
  document type definition (DTD).
• Document Type refers to a class of documents,
  including memos, letters, reports, manuals, etc.
• Root Element is the top-level element in an
  XML document.

6
XML Essentials Documents, Elements,
Attributes

• XML is specified in XML documents.
• Elements are the fundamental building blocks of
  XML documents.
• Attributes specify the characteristics of
  elements.
• XML documents are made up of markup and
  character data.
• Markup is the instruction to the programs that
  process and build XML documents.
• Character data is everything else.

7
XML Distinctions from SGML HTML (continued)

• SGML, HTML, XML share certain characteristics
• similar syntax
• the use of bracketed tags.
• XML HTML are descendants of SGML.
• XML is defined as an application profile of
  SGML. SGML is the Standard Generalized Markup
  Language defined by ISO 8879.

8
XML Distinctions from SGML HTML

• SGML (Standard Generalized Markup Language)
  provides arbitrary structure.
• SGMLs too difficult to implement for a web
  browser.
• HTML comes bound with a set of semantics
• HTML does not provide arbitrary structure.
• XML is being designed to deliver structured
  content over the web.
• XML (unlike HTML) is strict and requires that
  you follow specific W3C design guidelines.

9
XML A Familiar Example

• Assume you have access to a computer that can
  make food
• The computer has stored in it the following
  details
• about the ingredients,
• how to cook things,
• how to serve, etc.
• Assume you loaded (scanned and OCRs) into the
  computer a text version of an old-fashioned,
  Good Housekeeping recipe, the computer may or
  may not be able to read and decipher it.

10
XML An Example (continued)
But if you gave loaded something like the
following, a smart XML parser in the computer
would know what ingredients to look for and then
know how to put them together and cook them.
ltrecipegt (has the makings of a root
element) lttitlegtDoughlt/titlegt
ltingredientsgt ltingred_amtgt1
cuplt/ingred_amtgt ltingredgtflourlt/ingredgt
ltingred_amtgt1 tsp.lt/ingred_amtgt lt
ingredgtsaltlt/ingredgt ltingred_amtgt1/2
cuplt/ingred_amtgt ltingredgtwaterlt/ingredgt
lt/ingredientsgt ltdirectionsgt
ltlistgt ltelementgtMix flour and salt.lt/elementgt
ltelementgtSlowly stir in
water until dough is moist.lt/elementgt
ltcookinggt ltelementgtPut in microwave safe
bowl.lt/elementgt
ltelementgtltmethodgtMicrowavelt/methodgt on
lttempgthighlt/tempgt for lttimegt10
minuteslt/timegtlt/elementgt
lt/cookinggt lt/listgt lt/directionsgt lt/recipegt
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XML Essentials DTDs

• A Document Type Definition (DTD) is a set of
  syntax rules for tags.
• DTDs tells you what each element means and how
  to use it.
• DTDs describe
• what tags you can use in a document.
• what order they should appear in.
• which tags can appear inside other ones.
• which tags have attributes.
• etc.
• DTDs can be internal to an XML document, but
  it's usually a separate document or series of
  documents.
• A DTD is not required for an XML document to be
  used in a web page, but DTDs add structure and
  logic to an XML document.

12
XML An Example (continued)

• Using the recipe example, we can create the
  foundation of a DTD.

lt!DOCTYPE recipe lt!ELEMENT recipe (ingredients,
directions, body)gt lt!ELEMENT ingredients
(ingred_amt, ingred)gt lt!ELEMENT ingred_amt
(PCDATA)gt lt!ELEMENT ingred
(PCDATA)gt lt!ELEMENT directions (mix_instr,
cook_instr, method)gt lt!ELEMENT mix_instr
(PCDATA)gt lt!ELEMENT cook_instr
(PCDATA)gt lt!ELEMENT method
(PCDATA)gt lt!ENTITY wig Wow! Its good so easy
to make!gt gt ltrecipegt lttitlegtDoughlt/titlegt
ltingredientsgt ltingred_amt
gt1 cuplt/ingred_amtgt ltingredgtflourlt/ingredgt
ltingred_amtgt1
tsp.lt/ingred_amtgt ltingredgtsaltlt/ingredgt .
(etc.) . lt/recipegt
13
XML Toolkit

• Authoring DTD Creation Tools
• Markup Tools
• Parsers
• Browsers
• Office Suites
• Application Development Environments

14
XML Toolkit (continued) Product Options
15
XML Application Development Process

• There are three steps to writing an XML
  application.
• First, identify which XML documents will be used
  and how they will be accessed in the application.
  
• Each XML document can define its own set of
  elements or tags.
• Second, decide how the application will process
  the XML document.
• open the XML document and read it directly as a
  file.
• access the document through an XML parser (most
  common approach).
• note the parser usually makes the XML document
  available as an event stream or as a tree
  structure.
• Finally, write the business logic that operates
  on either the contents or the structure of the
  XML data. For example
• application that extracts email addresses from a
  contact list.
• application that simply reorder the elements of
  each entry in the contact list.

16
XML Application Development Process (continued)

• You can use a standard text editor to create
  tags and content of your XML document or, you can
  use an XML authoring tool.
• If you load an XML document into IE5 with no
  stylesheet at all, you get a nice tree-structured
  display with little /- icons that you can click
  to hide subtrees.

17
XML Application Development Process (continued)

• You can use a standard text editor to create
  tags and content of your XML document or, you can
  use an XML authoring tool.
• Display the document in an XML-friendly browser.
  
• If you load an XML document into IE5 with no
  stylesheet at all, you get a nice tree-structured
  display with little /- icons that you can click
  to hide sub trees.
• Supply display format instructions for the XML
  document.
• There are primarily two ways to format the
  display of an XML document
• Extensible Style Sheet (XSL), and
• Cascading Style Sheets (CSS)
• If you want to use style sheets, you have to
  link the stylesheet to the document
• For CSS lt?xml-stylesheet
  type"text/css" hrefa_stylesheet.css" ?gt
• For XSL lt?xml-stylesheet
  type"text/xsl" hrefa_stylesheet.xsl" ?gt

18
XML Application Scenarios

• Typically three types of XML applications
• Content Document Applications documents used to
  exchange info.
• Business Document Applications documents
  representing business entities to be used by
  people and in other business applications.
• Protocol Document Applications documents
  primarily used for the exchange of info among
  applications.

19
XML Application Scenarios Content Document
Applications

• XML used as substitute for HTML.
• Humans are principal consumers of these
  documents.
• Enables users to search metadata provided by XML
  tags.
• Enhances capability to personalize online
  document delivery.
• Enables users/viewers to perform local processing
  on document content.
• Development process resembles that of traditional
  web applications.
• Display style and format is very important.
• Examples include document archives, online news
  service (I.e., WSJ Interactive), real estate
  listing.

20
XML Application Scenarios Business Document
Applications

• XML docs contain info about fundamental business
  entities like customer, order, invoice, etc.
• Humans and software apps are principal consumers
  of business docs.
• Enables and facilitates document workflow
  automation.
• Enables synthesis of actual documents from
  existing business software.
• Encourages standardization of inter-organizational
  business document.
• Requires tools to map XML elements to current
  data models.
• Development process heavily influenced by
  business object modeling
• Display style and format important but not as
  much as in content apps.
• Back-end system integration takes on more
  importance.
• Example applications include ERP/HR integration,
  purchase authorization process automation,
  academic research repository and info transfer.

21

XML Application Scenarios Protocol Document
Applications

• XML docs serve as the data encoding framework for
  business protocols.
• Software applications are primary consumers of
  XML documents.
• Heavy reliance on agreed-upon DTDs.
• Very low to non-existent display and formatting
  requirement.
• Development process resembles that for networked
  file system I/O apps.
• Typically document distribution engines serving
  higher-level apps.
• Example applications include electronic software
  distribution (ESD), remote help desks.

22
XML Development - The Basics

• Include an XML declaration as the first
  statement in an XML document.
• One tag (the root element) contains all of the
  other tags.
• Every element must have a start and an end tag.
• Empty elements must end in /gt
• (Empty elements do not hold content between the
  start and end tags)
• Nesting of tags follow the LIFO rule last tag
  defined is the first tag closed.
• All attribute values are closed in quotes.
• Tags and entities always begin the same way.
• Tags begin with less than (lt) sign.
• Entities begin with an ampersand () sign.

23
XML Essentials DTD Composition

• DTDs consist of the following
• XML declaration tells the processor which
  version of XML to use.
• Document type declaration Tell the processor
  where the DTD is located.
• Element type declaration Defines the element
  type.
• Attribute list declaration defines the name,
  data type, and default value (if any) of each
  attribute associated with an element.
• Entity declaration defines a set of
  information that can be called by using its
  entity name.
• Notation declaration associates a notation
  name with information that can help find an
  interpreter of the notation.

24
XML Entities (continued) Parameter Entity
Example
lt!- Segment from sample Order Form DTD -gt lt!-
Document Structure -gt lt!ELEMENT order (addresses,
lineitems, payment)gt . . lt!- Payment Structure
-gt lt!ELEMENT payment (card PO)gt . .lt!- Card
Structure -gt lt!ELEMENT card (cardholder, number,
expiration)gt lt!ELEMENT cardholder
(PCDATA)gt lt!ELEMENT number (PCDATA)gt lt!ELEMENT
expiration (PCDATA)gt . . lt!- Attribute Rules
-gt lt!ATTLIST card CARDTYPE (VISA Mastercard
Amex) REQUIREDgt
CARDTYPE might show up later in the document as
follows . . ltpaymentgt ltcard
CARDTYPEVISAgt ltcardholdergtJoe
Blowlt/cardholdergt ltnumbergt41280000000000lt/
numbergt ltexpirationgt01/03lt/expirationgt
lt/cardgt lt/paymentgt . . lt/ordergt
25
XML Entities

• In general, an entity is used like an
  abbreviation.
• Entities are primarily structural elements.
• Whereas elements attributes enable
  specification of logical meaning.
• Associates an entity name with a content
  fragment.
• Four types
• Internal parsed allows definition of an alias
  for text fragment.
• External parsed enables inclusion of an entire
  file as part of a document.
• Unparsed enables insertion of arbitrary data
  into a document.
• Parameter enables creation of reusable and
  extensible design elements in a DTD.

26
Creating an XML Document

• Open an empty text file in a your text editor
  (Notepad, Word, WordPad, Visual Studio text
  editor, etc.)
• Type in the contents/elements of your XML file.
• Save the file with a .xml extension.
• Double click the file to display it under IE5
  (provided the extension is assigned to that
  application).
• IE5 has a built-in parser which will analyze
  the document and display error detection
  messages.
• IE5 parser only checks to confirm well-formed
  documents, not validity.
• IE5 can be updated to provide validation. Go to
  the following MS MSDN link.
• Revise the file as needed.

27
XML An Example (reprise)

• Using the recipe example, we can create the
  foundation of a DTD.

lt!DOCTYPE recipe lt!ELEMENT recipe (title,
ingredients, directions, body)gt lt!ELEMENT Title
(PCCHAR) lt!ELEMENT ingredients (ingred_amt,
ingred)gt lt!ELEMENT ingred_amt
(PCDATA)gt lt!ELEMENT ingred
(PCDATA)gt lt!ELEMENT directions (mix_instr,
cook_instr, method)gt lt!ELEMENT mix_instr
(PCDATA)gt lt!ELEMENT cook_instr
(PCDATA)gt lt!ELEMENT method
(PCDATA)gt lt!ENTITY wig Wow! Its good so easy
to make!gt gt ltrecipegt lttitlegtDoughlt/titlegt
ltingredientsgt ltingred_amt
gt1 cuplt/ingred_amtgt ltingredgtflourlt/ingredgt
ltingred_amtgt1
tsp.lt/ingred_amtgt ltingredgtsaltlt/ingredgt .
(etc.) lt/recipegt
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Displaying an XML Document

• Display instructions are kept separate from the
  XML document.
• Benefits are enhanced flexibility and greater
  change control.
• There are primarily two ways to format the
  display of an XML document
• Cascading Style Sheets (CSS)
• a file that contains element formatting
  instructions.
• enables display of XML document w/o using HTML.
• Exstensible Stylesheet Language (XSL)
• Like CSS, XSL stylesheets provide a set of rules
  for displaying tags.
• XSL stylesheets are XML documents.
• XSL stylesheets require DTDs and act in similar
  ways as other XML documents.

29
Displaying an XML Document (continued)

• There are at least two other ways to display
  XML documents.
• Using Data Binding techniques
• Allows you to link an XML document to n HTML
  page
• You can then bind standard HTML elements (i.e.,
  SPANs, TABLEs, etc.) to individual XML elements.
• The bound HTML elements will then automatically
  display the contents of the XML elements.
• Using Document Object Model scripts
• Allows you to access an XML document that has
  been linked to an HTML page using the Document
  Object Model.

30
XML Options for Displaying XML
31
Distinguishing Well-formed Valid XML Documents

• XML puts a premium on the organization and
  structure of documents.
• Well-formed XML documents are well-organized and
  accurate.
• Well-formed documents provide a convenient means
  for converting HTML to XML without writing and
  conforming to a DTD.
• Well-formed XML documents are not required to
  meet some of the extra criteria to be discerned
  as a valid XML document.
• The main difference between a well-formed and
  valid XML document is the absence or presence of
  a DTD.
• A valid XML document is well-formed (i.e.,
  accurate can be parsed by a non-validating
  parser)
• and it must also include a DTD.
• The structure of the valid document must be
  defined by the DTD.

32
Distinguishing Well-formed Valid XML Documents
(continued)
Example of a Well-formed XML document
lt?xml version 1.0?gt ltMEMOgt ltTITLEgt Memo with
Logolt/TITLEgt ltLOGO srcsmalllogo.gif/gt ltTOgtECT
481 Studentslt/TOgt ltFROMgtEllis Conferlt/FROMgt ltSUBJE
CTgtMy Errorlt/SUBJECTgt ltBODYgt Somehow I
accidentally deleted the MEMO /MEMO tags from
the original display of this XML example. It is
fixed now.gt lt/BODYgt lt/MEMOgt
33
Distinguishing Well-formed Valid XML Documents
(continued)
Example of a valid XML document
lt?xml version 1.0?gt lt!DOCTYPE MEMO
lt1ELEMENT MEMO (LOGO, TO, FROM, SUBSET,
BODY)gt lt!ELEMENT LOGO EMPTYgt lt!ELEMENT
TO (PCDATA)gt lt!ELEMENT FROM (PCDATA)gt lt!ELEMEN
T SUBJECT (PCDATA)gt lt!ELEMENT
BODY (PCDATA)gt gt ltMEMOgt ltTITLEgt Memo with
Logolt/TITLEgt ltLOGO srcsmalllogo.gif/gt ltTOgtECT
481 Studentslt/TOgt ltFROMgtEllis Conferlt/FROMgt ltSUBJE
CTgtMy Errorlt/SUBJECTgt ltBODYgt Somehow I
accidentally deleted the MEMO /MEMO tags from
the original display of this XML example. It is
fixed now.gt lt/BODYgt lt/MEMOgt
Inclusion of the DTD yields an XML document that
is not only well-formed but also valid.
34
Next Session Highlights

• Midterm Administered
• XML (continued)
• Next Session Reading Assignment
• Review chapter 2 of Fitzgerald text
• Review articles (available thru the class notes
  web site)
• XML Matters (required)
• Free XML Tools by Category (FYI)
• Web sites (linked thru the class notes web site)
• Key XML Links