XML

1
XML

• Ahmet Sentürk
• CmpE-587

2
Content

• XML
• XML Syntax
• XML Core Technologies
• WebDAV
• XML Web Services

3
What is XML

• self-describing documents
• textual markup (tags)
• a simplified version of SGML
• more suitable for use on the Web
• HTML provides rich facilities for display, it
  does not provide any standards-based way to
  manage data as data
• XML provides a data standard that can encode the
  content, semantics, and schemata for a wide
  variety of cases
• offers a universal way to describe and work with
  data

4
Benefits Of XML

• provides a universal ,powerful, flexible format
  for expressing data
• data delivered to the desktop can be manipulated
  locally
• Unicode
• a description of the structure of the data
• the data is now separate from the presentation
• XML offers a mechanism for adding meta-data or
  meta-content to HTML
• enables wide array of business applications to be
  implemented on the Internet

5
XML Syntax

• for describing your data
• ltbook nameThe Lord Of The Rings" lowfat"J.R.R.
  Tolkien"/gt
• begin and end tags and attributes
• case-sensitive
• text-based (similar to HTML)
• white space
• considered well-formed if it contains exactly one
  root element and all the child elements are
  nested properly within each other

6
XML Syntax

• store and transmit data
• an unlimited set of tags
• Strictly a Tree
• An example well-formed XML document
• lt?xml version"1.0"?gt
• lthamburgersgt
• lthamburger lowfat"dream on"gt
  ltnamegtCowBurgerlt/namegt ltdescriptiongtG
  reasy and good.lt/descriptiongt
  ltpricegt2.99lt/pricegt lt/hamburgergt
• lt/hamburgersgt

7
XML Namespaces

• provide a context for your XML document elements
• resolve elements to a particular implementation
  semantic
• Price Sale price or purchase price
• lt?xml version"1.0"?gt
• lthamburgers
• xmlnspurchase"http//fastfood.org/franchise/pr
  ices" xmlnssales"http//fastfood.org/custome
  r/prices"gt
• lthamburger lowfat"dream on"gt
• ltnamegtCowBurgerlt/namegt
• ltdescriptiongtGreasy and good.lt/descriptiongt
  ltpurchasepricegt0.99lt/pricegt
• ltsalespricegt2.99lt/pricegt
• lt/hamburgergt
• lt/hamburgersgt

8
XML Core Technologies

• Validation Technologies
• Schemas
• a formal specification of the rules of an XML
  document
• Document Type Definitions
• lt!DOCTYPE hamburgers SYSTEM "hamburger.dtd"gt

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Hamburger.dtd

• lt!ELEMENT hamburgers(hamburger)gt
• lt!ELEMENT hamburger(name, description, price)gt
• lt!ATTLIST hamburgerlowfat CDATA IMPLIEDgt
• lt!ELEMENT name(PCDATA)gt
• lt!ELEMENT description(PCDATA)gt
• lt!ELEMENT price(PCDATA)gt
• PCData (parsed character data)

10
XML Core Technologies

• XML-Data
• lt?xml version"1.0"?gt
• ltSchema xmlns"schemas-microsoft-comxml-data"gt
• ltElementType name"name" /gt
• ltElementType name"description" /gt
• ltElementType name"price" /gt
• ltAttributeType name"lowfat" /gt
• ltElementType name"hamburger" /gt
• ltelement type"name" maxOccurs"1" /gt
• ltelement type"description" maxOccurs"1" /gt
  
• ltelement type"price" maxOccurs"1" /gt
• ltattribute type"lowfat" maxOccurs"1" /gt
• lt/ElementTypegt
• ltElementType name"hamburgers" model"closed"gt
  
• ltelement type"hamburger" maxOccurs"" /gt
• lt/ElementTypegt
• lt/Schemagt

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XML Core Technologies

• Processor (API) Technologies
• DOM
• in-memory tree representation of the XML document

12
XML Core Technologies

• Processor (API) Technologies
• SAX
• event-driven XML parsing
• doesn't require the entire XML file to be loaded
  into memory
• event handlers to just-in-time process

13
XML Core Technologies

• Transformation Technologies
• XSL Patterns
• /hamburgers/hamburger_at_lowfat"yes"/price
• XSL
• XML File
• lt?xml version"1.0"?gt
• lthamburgersgt
• lthamburger lowfat"dream on"gt
  ltnamegtCowBurgerlt/namegt ltdescriptiongtGreasy
  and good.lt/descriptiongt ltpricegt2.99lt/pricegt
• lt/hamburgergt
• lt/hamburgersgt

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XML Core Technologies

• XSL Transformation
• lt?xml version"1.0"?gt
• ltxslstylesheet xmlnsxslhttp//www.w3.org/TR/W
  D-xsl "gt
• ltxsltemplate match"/"gt
• lthtmlgt
• ltbodygt
• lth1gthamburgerslt/h1gt
• ltxslfor-each select"hamburgers_at_lowfat"dream
  on"gt ltligtltxslvalue-of
  select"name"/gt, ltxslvalue-of select"price"/gt,
  
• ltxslvalue-of select"description"/gtlt/ligt
  
• lt/xslfor-eachgt
• lt/bodygt
• lt/htmlgt
• lt/xsltemplategt
• lt/xslstylesheetgt

15
XML Core Technologies

• HTML Output
• lthtmlgt
• ltbodygt
• lth1gthamburgerslt/h1gt
• ltolgt
• ltligtCowBurger, 2.99, Greasy and good.lt/ligt
• lt/olgt
• lt/bodygt
• lt/htmlgt

16
XML Core Technologies

• Linking Technologies
• XLink
• lthamburger xmllink"simple" HREF
  "http//fastfood.org/hamburger.htm"gtlt/hamburgergt
• XPointer
• child(2,hamburger)
• Other Technologies
• Mathematical Markup Language (MathML)
• Synchronized Multimedia Integration Language
  (SMIL)
• Vector Markup Language (VML)

17
WebDAV

• Web Distributed Authoring and Versioning
• Communicating XML Data over the Web
• an important communication protocol for the Web
  as an extension to HTTP 1.1
• useful in client/server architecture

18
WebDAV

• Protocol Problem
• HTTP for static documents intended for viewing
• lost update problem
• Three major major concerns of collaborative
  authoring in WebDAV
• Overwrite Protection
• Resource Management
• Document Properties

19
The Format of WebDAV Requests

• set of methods that clients can use to
  communicate with servers
• Options, Head, and Trace
• Get
• Put and Post
• Delete
• Mkcol
• PropFind and PropPatch
• Copy and Move
• Lock and Unlock

20
What XML Means to WebDAV

• HTTP communicate with headers
• WebDAV require a great deal of information to be
  associated with both requests and responses
• Because of its inherent extensibility, XML was
  chosen to describe how these instructions are
  communicated
• A method of formatting instructions describing
  how data is to be handled.
• A method of formatting complex responses from the
  server.
• A method of communicating customized information
  about the collections and resources handled.
• A flexible vehicle for the data itself.

21
XML Web Services

• fundamental building blocks in the move to
  distributed computing on the Internet
• communication and collaboration among people and
  applications
• application integration
• constructed using multiple XML Web services
• from various sources
• work together
• regardless of where they reside or how they were
  implemented
• primary advantages
• allows programs written in different languages on
  different platforms to communicate with each
  other in a standards-based way

22
XML Web Services

• many definitions
• XML Web Services expose useful functionality to
  Web users through a standard Web protocol, SOAP.
• XML Web services provide a way to describe their
  interfaces in enough detail to allow a user to
  build a client application to talk to them,
  called a Web Services Description Language (WSDL)
  document
• XML Web services are registered so that potential
  users can find them easily, with Universal
  Discovery Description and Integration (UDDI).

23
What Can I Do With XML Web Services

• information sources that you could easily
  incorporate into applications
• more powerful applications that use XML Web
  services as building blocks

24
SOAP

• communication protocol for XML Web services
• defines the XML format for messages
• Remote Procedure Calls
• SOAP message containing a callable function
• parameters to pass to the function, is sent from
  the client
• server returns a message with the results of the
  executed function
• define security for web services

25
Why Should I Use SOAP?

• implemented on many different hardware and
  software
• can be used to link separate systems
• RPC
• HTTTP

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WSDL

• a WSDL file is an XML document that describes a
  set of SOAP messages and how the messages are
  exchanged
• based on the XML Schema
• defines where the service is available and what
  communications protocol is used to talk to the
  service

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WSDL Document Structure

• Abstract Definitions (define SOAP messages )
• Types Machine- and language-independent type
  definitions
• Messages Contains function parameters or
  documentdescripttions
• PortTypes function signatures (operation name,
  input parameters, output pameters
• Concrete Descriptions
• Bindings Specifies binding(s) of each operation
  
• Services Specifies port address(es) of each
  binding, syntax for calling methods

28
UDDI

• yellow pages of Web services
• Search web service
• Read about it
• Get more information about service
• to reach a significant market, you need UDDI
• an XML file that describes a business and the
  services it offers

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UDDI

• 3 parts of an entry in UDDI
• white pages describe the company offering the
  service
• yellow pages include industrial categories
• green pages describe the interface to the
  service
• UDDI directory includes several ways to search
  for the services

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What XML Do You Post?

• SOAP Envelope
• lt?xml version'1.0' encoding'UTF-8'?gt
• ltEnvelope xmlns'http//schemas.xmlsoap.org/soap/
  envelope/'gt
• ltBodygtlt/Bodygt
• lt/Envelopegt
• Contents of body can be any query
• ltfind_business generic"1.0" xmlns"urnuddi-org
  api"gt ltnamegtMicrosoftlt/namegt
• lt/find_businessgt

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How Do You Post the XML?

• Form a Jscript file or HTML page by XMLHTTP
• http new ActiveXObject("Microsoft.XMLHTTP")
  http.open("POST", url, false)
  http.setRequestHeader("Accept","text/xml")
  http.setRequestHeader("Cache-Control","no-cache")
  http.setRequestHeader("SOAPAction",'""')
  http.send(msg)

32
What Do You Get Back?

• XML of course
• ltbusinessList generic"1.0" operator"Microsoft
  Corporation" truncated"false"
  xmlns"urnuddi-orgapi"gt
• ltbusinessInfosgt
• ltbusinessInfo businessKey"0076B468-EB27-42E5-AC
  09-9955CFF462A3"gt
• ltnamegtMicrosoft Corporationlt/namegt
• ltdescription xmllang"en"gtEmpowering people
  through great software - any time, any place
  and on any device is Microsofts vision. As the
  worldwide leader in software for personal and
  business computing, we strive to produce
  innovative products and services that meet our
  customer's lt/descriptiongt
• ltserviceInfosgt
• ltserviceInfo businessKey"0076B468-EB27-42E5-AC
  09-9955CFF462A3" serviceKey"1FFE1F71-2AF3-45FB-
  B788-09AF7FF151A4"gt
• ltnamegtWeb services for smart searchinglt/namegt
  lt/serviceInfogt

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.NET application architecture

• multiple Web Services that work together to
  provide data and services for the application

34
Generic Architecture for a Web Service
35
Reliable XML Web Services

• Standards Based
• Acknowledged Delivery
• Ordered Delivery
• Symmetric Conversations
• Promotes Asynchronous Processing

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Synchronous Messaging

• The connection may be broken by an external
  source, dropping either the request or response
• The server may timeout because it is offline or
  overloaded
• The server process may be dependant upon down
  stream services that have uncontrollable response
  times.

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Synchronous Messaging
38
Asynchronous Model