XML Technology

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XML Technology

• Nizar Mabroukeh
• nizar_at_ccse.kfupm.edu.sa
• COE 445
• KFUPM April, 2001

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We will cover

• What is XML?
• Components of an XML Document
• Document Type Definition (DTD)
• XML Data Islands
• Parsing XML and DOM
• XML presentation with CSS, XSL and XSLT
• XPath, XML and Database Integration
• Why use XML?
• Creating your own XML vocabulary
• Review of XML Applications and Tools
• XML Resources

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What is XML?
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Markup Languages

• SGML
• Standard Generalized Markup Language
• Mother of Markup Languages
• HTML
• Most popular presentation language for web
• XML
• Draws heavily on the merits shortcomings of
  HTML SGML

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Issues with HTML

• Merits
• Very easy to use learn
• Presentation technology
• It is the most popular
• Shortcomings
• NOT a data technology
• Poor Searching
• There is no Intelligence of content/data
• We loose meaning association with content
• Data cannot be represented hierarchically
• Limited set of tags

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How does XML look?

• Simple XML data would look like
• ltbookgt
• lttitlegt XML Tech lt/titlegt
• ltauthorgt YAG lt/authorgt
• ltlevelgt Freshman lt/levelgt
• lt/bookgt
• ltbookgt Called the root node

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XML HTML

• Similar in appearance
• Both are based on SGML
• BUT
• XML describes data
• HTML displays data

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XML (eXtensible Markup Language)
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What Is XML?

• XML is a
• platform-independent,
• self-describing,
• expandable,
• standard data exchange format
• that can be used either independently or
• embedded and used within other solutions.

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Platform Independent

• Windows
• Unix
• Macintosh
• Mainframe

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Self-Describing

• Example
• ltDATEgtJuly 26, 1998lt/DATEgt
• Describes the information, not the presentation.
  Format flexible.

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Expandable Extensible

• HTML has a fixed set of tags
• ltH1gt, ltBgt, ltPREgt
• XML lets you have your own tags
• ltdangerous-substancegt, ltShakespearean-charactergt
  , ltcash-equivalentgt

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Standard

• W3C (World Wide Web Consortium) www.w3c.org
• XML 1.0 specification was issued as
  standards-based text format for interchange of
  data as of February 1998.
• W3C XML Working Group designed XML as a
  simplified subset of SGML

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Standard

• XML specification does not define any particular
  tag names (like HTML), instead it defines general
  syntactic rules enabling developers to create
  their own domain-specific vocabularies of tags.

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Context

• Greater context to the information
• Tree structure is natural in XML

ltbalance-sheetgt lttotal-assetsgt ltasset-type"cur
rent"gt ltamount-period"1998"gt ltamountgt
41,000,000 lt/amountgt lt/amount-periodgt
lt/asset-typegt lt/total-assetsgt lt/balance-sheetgt
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Freedom

• Extensible markup language
• Customized tags
• Tags give meaning to the content
• Separates data from style

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Why XML?

• Derived as a subset of SGML
• Allows you to define your own tags
• XML ltauthorgt YAG lt/authorgt
• HTML ltBgt YAG lt/Bgt
• Provides meaningful readable data
• Meaning searches can be performed
• Much simpler than SGML
• SGML spec 300 pages, XML 33 pages
• Purely a Data Technology
• Supports compound documents.

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XML Advantages

• Web based
• Extensible
• License-free
• Platform independent
• Single end-to-end IT solution for electronic
  information exchanges

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XML Documents

• Authoring XML

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XML Elements

• An XML element is made up of a start tag, an end
  tag, and data in between. The start and end tags
  describe the data within the tags, which is
  considered the value of the element.
• For example, the following XML element is a
  ltchairmangt element with the value Sadiq Sait"
• ltchairmangtSadiq Saitlt/chairmangt
• Elements can be empty, to represent an empty
  element ltchairman/gt

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XML Attributes

• An element can optionally contain one or more
  attributes. An attribute is a name-value pair
  separated by an equal sign ().
• Example
• ltCITY ZIP31261"gtDhahranlt/CITYgt
• Here, ZIP31261" is an attribute of the ltCITYgt
  element. Attributes are used as meta information

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XML is

• Case-sensitive

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Parts of an XML document

Version Declaration
Document Type Definition (DTD)
ltrootgt BODY lt/rootgt
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Version Declaration

• lt?xml version1.0 encodingUTF-8
  standaloneyes?gt
• Encoding
• Supports Unicode 8, Unicode 16 Others
• In short Provides for multi-lingual data
• Standalone
• Indicates whether the document has any markup
  declarations that are external to the document

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XML data

• This is how XML data would look like (the body of
  the document)
• ltbooksgt
• ltbookgt
• ltnamegt Codebook 6.0 lt/namegt
• ltauthorgt YAG lt/authorgt
• ltlevelgt Intermediate Advanced lt/levelgt
• lt/bookgt
• ltbookgt
• ltnamegt Jave for Beginners lt/namegt
• ltauthorgt Dale lt/authorgt
• ltlevelgt Beginner lt/levelgt
• lt/bookgt
• lt/booksgt

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XML Document Rules

• ltbooksgt
• ltbookgtlt/bookgt
• ltbook ISBN21-458-65-0gt
• ltpara id1 sid4gt
• lt?xml version1.0?gt

• ONE Root element
• ALL tags start AND end
• Tags cannot overlap and are case sensitive
• Attribute values enclosed in quotes
• Attributes not repeated in an element
• FIRST item must be

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Two types of XML documents

• Well-formed XML documents
• Valid XML documents

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Well-formed document

• Must contain one or more elements
• Must contain a uniquely named root element
• All other elements within the root element must
  be nested correctly
• An XML parser will reject malformed
  documents(the method of rejection will vary by
  parser author)
• Documents that contain XML and HTML tags are
  common
• HTML within an XML document must be well-formed

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Valid XML document

• The XML document must be well formed
• Should contain a Document Type Definition
• DTD is a schema which contains the constraints
  for the XML document
• It contains Element definitions and their
  Attributes
• Attributes should comply with the following rules
• Cannot contain lt, or a single or .
• Elements must be nested correctly

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Document Type Definition

• DTD is a text document that defines the lexicon
  of legal names for tags in a particular XML
  vocabulary
• It also defines how tags should be nested
• It can be written as code inside the XML file or
  specified externally as a separate text file with
  extension .dtd

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Sample DTD

• lt!-- Uses EBNF (Extended Backus Naur Form) --gt
• lt!DOCTYPE book
• lt!ELEMENT book(name,author,level)gt
• lt!ELEMENT name(PCDATA)gt
• lt!ELEMENT author(PCDATA)gt
• lt!ELEMTNT level(PCDATA)gt
• lt!ATTLIST author email CDATA IMPLIEDgt
• gt
• DTD may be specified externally with .dtd
  extension lt!DOCTYPE book SYSTEM book.dtdgt

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More on DTD

• Special software can help you build your DTD
  document visually instead of having to write all
  this weird code, example software package is XML
  Authority from Extensibility
• An XML document is associated with a
  corresponding DTD document for validation using
  the lt!DOCTYPEgt tag

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Why use a DTD?

• Application independent way of sharing data
• Industries or trading parties can agree on a
  standard for interchanging data
• Verification that data received from trading
  parties is valid.

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Complete XML document

• lt?xml version1.0 ?gt
• lt!DOCTYPE book
• lt!ELEMENT book(name,author,level?)gt
• lt!ELEMENT name(PCDATA)gt
• lt!ELEMENT author(PCDATA)gt
• lt!ELEMTNT level(PCDATA)gt
• gt
• ltbookgt
• ltnamegt Codebook 6.0 lt/namegt
• ltauthorgt YAG lt/authorgt
• ltlevelgt Intermediate Advanced lt/levelgt
• lt/bookgt

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OR

• lt?xml version1.0 ?gt
• lt!DOCTYPE book SYSTEM book.dtdgt
• ltbookgt
• ltnamegt Codebook 6.0 lt/namegt
• ltauthorgt YAG lt/authorgt
• ltlevelgt Intermediate Advanced lt/levelgt
• lt/bookgt

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XML Document Pluses

• Tightly Structured
• Extensible
• Easily models data
• Useful for applications and transferbetween
  applications
• Interchangeable

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XML Data Islands

• XML inside HTML

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XML Data Islands

• A data island is an XML document that exists
  within an HTML page.
• It allows you to script against the XML document
  without having to load it through script or
  through the ltOBJECTgt tag.
• Almost anything that can be in a well-formed XML
  document can be inside a data island

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How to create XML data island

• The XML for a data island in HTML can be either
• Inline using ID,
• or called from an outside xml file using SRC,
• or created using a ltscriptgt tag

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Inline data island

• The ltXMLgt element marks the beginning of the data
  island, and its ID attribute provides a name that
  you can use to reference the data island.
• ltXML ID"XMLID"gt
• ltcustomergt
• ltnamegtMark Hansonlt/namegt ltcustIDgt81422lt/custIDgt
  
• lt/customergt
• lt/XMLgt

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XML referenced from outside file

• referenced through a SRC attribute on the ltXMLgt
  tag
• ltXML ID"XMLID" SRC"customer.xml"gtlt/XMLgt

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Created using ltscriptgt tag

• ltSCRIPT LANGUAGE"xml" ID"XMLID"gt ltcustomergt
  
• ltnamegtMark Hansonlt/namegt ltcustIDgt81422lt/cust
  IDgt
• lt/customergt
• lt/SCRIPT gt

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Parsing XML
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What is XML Parsing

• For a computer program to access the structured
  information in the document in a meaningful way,
  parsing is required
• The parser first reads the stream of characters
  and recognizes the syntactic details of elements,
  attributes and text in the document
• Then, the parser exposes the hierarchical set of
  information in the document as a tree of related
  elements, attributes and text items

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• The logical tree of information items created
  after parsing the XML document, is called the
  Information Set or Infoset
• This can then be manipulated in different ways
  and data extracted for usage in applications,
  databases,etc

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XML Parsers

• Always check for well-formedness
• Can be validating or non-validating
• Validation required association with DTD document
• Included in Microsoft Internet Explorer 5.0
• Language-neutral programming model
• By using W3C XML 1.0 and XML DOM it supports
  JavaScript, VBScript, Java, C, Perl

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Manipulating XML using the DOM

• W3C provides a standard API called the Document
  Object Model (DOM) to access an XML documents
  infoset
• The DOM API provides a complete set of operations
  to programmatically manipulate the node tree
  including navigating the nodes in the hierarchy,
  creating and appending new nodes, removing nodes,
  etc.

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• Once you are done with making changes to the node
  tree you can save it and serialize the infoset
  back into an XML document
• xml infoset

parsing
serialization
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DOM Properties Methods

• An XML document object is created when an XML
  data island is loaded and parsed. and it has
  Properties Methods
• XMLDocument Returns a reference to the
  XML DOM exposed by the object
• documentElement Returns the root element
• childNodes Returns a node list containing
  children (if any)
• item(id) Access individual nodes through an
  index (zero based)
• text Returns the text content of the node
• Lets look at an example

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DOM Example

• ltXML ID"xmlDocument"gt
• ltclassgt
• ltstudent studentID"13429"gt
• ltnamegtJane Smithlt/namegt
• ltGPAgt3.8lt/GPAgt
• lt/studentgt
• lt/classgt
• lt/XMLgt
• All of the below begin with xmlDocument.documentEl
  ement.childNodes.item(0)
• .childNodes.item(0).text Returns "James Smith"
• .childNodes.item(1).text Returns "3.8"
• .text Returns "James Smith 3.8" i.e.
  name GPA
• Note Everything is case sensitive here

Data Island
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XML Presentation

• Viewing XML

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Viewing XML

• Unlike HTML, XML does not predefine display
  properties for specific elements.
• C Data Source Object (DSO)
• Binds XML to HTML and gives better performance,
  built in IE 5.0
• Cascading Style Sheets (CSS)
• Extended Stylesheet Language (XSL)

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CSS

• Separate file with a .css extension
• object, property nameproperty value
• DIV colorred font-size16pt
• / Comments are entered the C way here /

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Displaying XML with CSS

• paragraph
• COLOR red
• FONT-FAMILY 'Book Antiqua'
• FONT-VARIANT small-caps
• FONT-WEIGHT bolder
• preamble
• COLOR blue
• FONT-FAMILY 'Book Antiqua'
• FONT-VARIANT small-caps
• FONT-WEIGHT bolder
• lt?xml-stylesheet type"text/css"
  href"const.css"?gt

• Modify the presentation of XML Documents
• Follow normal CSS syntax
• Referenced in the XML source document

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XSL

• eXtended Stylesheet Language
• Syntax is similar to XML
• In fact, XSL is written in XML

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• The aim of XSL is to provide a simple but
  powerful stylesheet syntax, which can be used to
  define how XML documents should appear on the
  screen.
• An XSL stylesheet transforms an XML document into
  a suitable form for presentation
• It allows us to control how and which parts of
  the documents should be shown to the user.

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• The XSL processor takes an XML document as input,
  and translates it into a different XML document
  suitable for output. This resultant XML document
  can be passed through a separate tool to add the
  finishing touches ready for presentation.

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Displaying XML with XSL

• ltxslfor-each selectbooks/book"
  order-byauthor"gt
• ltTR VALIGN"top" gt ltTDgt
• ltxslvalue-of select"name"/gt
• lt/TDgt
• ltTDgt
• ltxslvalue-of selectauthor"/gt
• lt/TDgt
• lt/TRgt
• lt/xslfor-eachgt

• More powerful than CSS
• XSL documents are XML documents

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XSL Styling Tools
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Integrated use of XML
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XSLT

• eXtended Stylesheet Language for Transformations
• Transforms XML from one tree-based structure to
  another

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Advantages of XSLT

• Convert between XML vocabularies used by
  different applications
• Present data from an XML document by transforming
  it into HTML, or another format thats
  appropriate to the user or special device
  requesting the data

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Database Integration

• Query and Search XML documents

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XPath

• XML Path Language is a W3C standard
• It is a declarative language
• Used to interrogate an XML document to select
  subsets of information

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• XPath provides a method for addressing parts of
  an XML document.
• Allows string, number and boolean manipulation
• Treats XML document as set of nodes, allows
  matching
• It is called a Path language because it is design
  like the path notation in URLs and files in
  directories

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XPath Example

• /MovieList/Movie/Cast/Actor/ returns all info
  about all actors
• /MovieList/Movie/Cast/ returns all info about
  Cast including
• that of Director and Actor and
• Actress
• To find attributes instead of elements we use _at_
• /MovieList/Movie/_at_Title returns titles of all
  movies
• //Actress/_at_Role returns the Role of
  any Actresses
• anywhere in the document

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• Find the Cast of any movies directed by
• Minghella with a running time greater than
• 130 minutes
• /MoiveList/MovieDirector/LastManghella and
  _at_RunningTime gt130/Cast

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Where to Use XPath
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Using XPath

• Create an XPath for each unit of information
• Carry the XPaths with the information as it is
  transformed into other formats
• Use XPaths to link language strings and labels
  with the information they describe
• Generate an XSL stylesheet that uses the XPaths
  to generate the outgoing message

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You should be using XML

• More reasons for you to use XML

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Why should I use XML

• XML enables a data web of information services
  it is vendor-neutral, platform-neutral,
  language-neutral technology
• Simplifies application integration, consider the
  following example ?

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Simplifies Integration

• If a company has
• Machines running OS from Sun, HP, IBM
• Databases from Oracle, IBM, Microsoft
• Packaged applications from Oracle, SAP
• An XML-based representation of data and the HTTP
  protocol might be the only things these various
  systems can ever hope to have in common!
• Especially if you want to integrate them over the
  Internet

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Why should I use XML

• XML also simplifies Information Publishing and
  Reuse
• With XML and XSLT you can easily
• Separate data from presentation, allowing you to
  change the look of information without affecting
  application code
• Publish the same data using output styles
  specific to each kind of requesting device
  browser, cell phone, PDA or another computer,
  etc.

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• WML Wireless Markup Language for cell phones and
  PDAs
• SVG Scalable Vector Graphics language for
  rendering rich, data-driven images
• XSL Formatting Objects for high-quality printed
  output

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Creating your own XML Vocabulary
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XML Vocabulary

• The set of XML elements and attributes for a
  certain application is called an XML Vocabulary
• Can be used in more than one XML document for the
  same application

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Create your own

• Begin each document with an XML decleration
• lt?xml version1.0?gt (case-sensitive)
• Use only one top-level document element
• cannot be repeated
• Match opening and closing tags properly (notice
  case-sensetivity)

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• Add comments between
• lt!-- and --gt characters
• Start element and attribute names with a letter.
  Cannot contain spaces
• Put attributes in the opening tag
• Enclose attribute values in matching quotes

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• Use only simple text as attribute values
• Use lt and amp instead of lt and for literal
  less-than and ampersand characters
• Write empty elements as ltElementName/gt
• If you follow these rules then your document will
  be a well-formed XML document

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Review of Applications and Tools
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XML Tools

• Help author the grammars (Schema, Filter,
  Updates)
• View, Edit Manage XML
• Define mappings between XML logical views
  Databases.

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How is XML used?

• Publishing
• Create once, use many
• Database Management
• Database integration
• e-Business
• Key driver

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XML Creation Tools

• Two schools
• Data centric
• Document centric

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Microsoft XML Notepad
msdn.microsoft.com/xml/notepad

• Free
• Tree-based
• Great search

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CueSoft eXML
www.cuesoft.com

• Tree or source view
• Attribute handling
• No search
• No nav bar in source view

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Techno2000 Clip!

• Powerful
• Flexible
• Wizards
• DTD creation

http//www.t2000-usa.com/download/download_index.h
tml
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Vervet Logic XML Pro

• More expensive

www.vervetlogic.com
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Document Oriented

• Examples
• SoftQuad XMetaL
• Corel WordPerfect 9
• Arbortext Adept Editor
• Not as good for data development
• Require DTD or equivalent

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XSL Tester
www.vbxml.com

• Free
• Open source
• VB

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XML Authority from Extensibility
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XML Authority from Extensibility

• DTDs
• Schema

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Other Choices

• Web-based
• DTD Generator
• www.pault.com/Xmltube/dtdgen.html
• IBM Suite
• Visual DTD
• Visual XML Transformation

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Utilities

• File manipulation
• XML Junction
• www.xmljunction.com
• ODBC2XML

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Security

• IBMs XML Security Suite
• www.alphaworks.ibm.com/tech/xmlsecuritysuite

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Programming and XML

• Programming tools and environments
• Java including JAXP
• Visual Basic (VB) and Visual Basic for
  Applications (VBA)
• Databases and other tools
• Document vs. event driven processing (DOM vs. SAX)

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Resources for XML
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Software Sources

• Interesting sites
• www.xmlsoftware.com
• alphaworks.ibm.com
• www.garshol.priv.no/download/xmltools/std_ix.html

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WebSites

• The Mother Ship
• www.w3c.org/xml
• Heavy Stuff
• www.ibm.com/developer/xml
• msdn.microsoft.com/xml
• www.oracle.com/xml/
• java.sun.com/xml/

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More Resources

• XML Information sites
• www.xmlinfo.com
• www.xml.com
• www.xml.org
• www.xmlelephant.com
• metalab.unc.edu/xml/
• www.ucc.ie/xml/
• XML Tutorials
• www.xml101.com

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More Resources

• XSL Information
• http//www.mulberrytech.com/xsl/xsl-list
• VB XML Information
• mailtovbxml-subscribe_at_onelist.com

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And finally

• Were only at the very start of the Web
  revolution.
• XML is the fundamental building block
• XML technology is moving forward, and Standards
  are rapidly evolving

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Thank You