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    XML

    XML stands for extensible Markup Language.

    XML is designed to transport and store data.

    XML is important to know, and very easy to learn.

    HTML was designed to display data.

    What is XML?

    • XML stands for Extensible Markup Language

    • XML is a markup language muc like HTML

    • XML was designed to carry data, not to display data

    • XML tags are not predefined. !ou must define your own tags

    • XML is designed to be self"descriptive

    • XML is a #$% &ecommendation

    W3C Stands for  te #orld #ide #eb %onsortium.

    The Difference between XML and HTML

    XML is not a replacement for HTML.

    XML and HTML were designed wit different goals'

    • XML was designed to transport and store data, wit focus on wat data is

    • HTML was designed to display data, wit focus on ow data looks

    HTML is about displaying information, wile XML is about carrying information

    XML Does Not DO Anything

    Maybe it is a little ard to understand, but XML does not () anyting. XML was created

    to structure, store, and transport information.

    Te following example is a note to Tove, from *ani, stored as XML'

    +note+toTove+-to+from*ani+-from+eading&eminder+-eading

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    +body(ont forget me tis weekend/+-body+-note

    Te note above is 0uite self"descriptive. 1t as sender and receiver information, it alsoas a eading and a message body.

    2ut still, tis XML document does not () anyting. 1t is 3ust information wrapped intags. 4omeone must write a piece of software to send, receive or display it.

    With XML You n!ent Your Own Tags

    Te tags in te example above 5like +to and +from6 are not defined in any XMLstandard. Tese tags are 7invented7 by te autor of te XML document.

    Tat is because te XML language as no predefined tags.

    Te tags used in HTML are predefined. HTML documents can only use tags defined inte HTML standard 5like +p, +8, etc.6.

    XML allows te autor to define is-er own tags and is-er own document structure.

    XML is Not a "e#$ace%ent for HTML

    XML is a co%#$e%ent to HTML&

    1t is important to understand tat XML is not a replacement for HTML. 1n most webapplications, XML is used to transport data, wile HTML is used to format and display

    te data.

    My best description of XML is tis'

    XML is a software' and hardware'inde#endent too$ for carrying infor%ation&

    XML is a W() "eco%%endation

    XML became a #$% &ecommendation on 9ebruary 8:, 8;;

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    XML is used in many aspects of web development, often to simplify data storage andsaring.

    XML *e#arates Data fro% HTML

    1f you need to display dynamic data in your HTML document, it will take a lot of work toedit te HTML eac time te data canges.

    #it XML, data can be stored in separate XML files. Tis way you can concentrate onusing HTML for layout and display, and be sure tat canges in te underlying data willnot re0uire any canges to te HTML.

    #it a few lines of *ava4cript code, you can read an external XML file and update tedata content of your web page.

    XML *i%#$ifies Data *haring

    1n te real world, computer systems and databases contain data in incompatibleformats.

    XML data is stored in plain text format. Tis provides a software" and ardware"independent way of storing data.

    Tis makes it muc easier to create data tat can be sared by different applications

    XML *i%#$ifies Data Trans#ort

    )ne of te most time"consuming callenges for developers is to excange databetween incompatible systems over te 1nternet.

    Excanging data as XML greatly reduces tis complexity, since te data can be read bydifferent incompatible applications.

    XML *i%#$ifies +$atfor% )hanges

    =pgrading to new systems 5ardware or software platforms6, is always time consuming.Large amounts of data must be converted and incompatible data is often lost.

    XML data is stored in text format. Tis makes it easier to expand or upgrade to newoperating systems, new applications, or new browsers, witout losing data.

    XML Ma,es Your Data More A!ai$ab$e

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    (ifferent applications can access your data, not only in HTML pages, but also from XMLdata sources.

    #it XML, your data can be available to all kinds of 7reading macines7 5Handeldcomputers, voice macines, news feeds, etc6, and make it more available for blind

    people, or people wit oter disabilities.

    XML is used to )reate New nternet Languages

     > lot of new 1nternet languages are created wit XML.

    Here are some examples'

    • #4(L for describing available web services

    • #>? and #ML as markup languages for andeld devices

    • &44 languages for news feeds

    An -xa%#$e XML Docu%ent

    XML documents use a self"describing and simple syntax'

    +@xml versionA78.:7 encodingA714)"

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    +-note

    !ou can assume, from tis example, tat te XML document contains a note to Tovefrom *ani.

    -xa%#$e.

    Te image above represents one book in te XML below'

    +bookstore  +book categoryA7%))D1F7

      +title langA7en7Everyday 1talian+-title  +autorFiada (e Laurentiis+-autor  +yearG::B+-year  +price$:.::+-price  +-book  +book categoryA7%H1L(&E7  +title langA7en7Harry ?otter+-title  +autor* D. &owling+-autor  +yearG::B+-year  +priceG;.;;+-price  +-book  +book categoryA7#E27  +title langA7en7Learning XML+-title  +autorErik T. &ay+-autor  +yearG::$+-year  +price$;.;B+-price  +-book+-bookstore

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    Te root element in te example is +bookstore. >ll +book elements in te documentare contained witin +bookstore.

    Te +book element as C cildren' +title,+ autor, +year, +price.

    XML *yntax "u$es

    Te syntax rules of XML are very simple and logical. Te rules are easy to learn, andeasy to use.

    A$$ XML -$e%ents Must Ha!e a )$osing Tag

    XML Tags are )ase *ensiti!e

    XML -$e%ents Must be +ro#er$y Nested

    XML Docu%ents Must Ha!e a "oot -$e%ent

    XML Attribute /a$ues Must be 0uoted

    -ntity "eferences

    4ome caracters ave a special meaning in XML.

    1f you place a caracter like 7+7 inside an XML element, it will generate an error becausete parser interprets it as te start of a new element.

    Tis will generate an XML error'

    +messageif salary + 8::: ten+-message

    To avoid tis error, replace te 7+7 caracter wit an entity reference'

    +messageif salary ltI 8::: ten+-message

    There are 1 #redefined entity references in XML.

    ltI + less tangtI greater tan

    ampI ampersand

    aposI apostrope

    0uotI 7 0uotation mark

    Note. )nly te caracters 7+7 and 77 are strictly illegal in XML. Te greater tancaracter is legal, but it is a good abit to replace it.

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    )o%%ents in XML

    Te syntax for writing comments in XML is similar to tat of HTML.

    +/"" Tis is a comment ""

    XML Attributes

    XML elements can ave attributes, 3ust like HTML.

     >ttributes provide additional information about an element.

    XML Attributes

    1n HTML, attributes provide additional information about elements'

    +img srcA7computer.gif7+a refA7demo.asp7

     >ttributes often provide information tat is not a part of te data. 1n te example below,te file type is irrelevant to te data, but can be important to te software tat wants tomanipulate te element'

    +file typeA7gif7computer.gif+-file

    XML Attributes Must be 0uoted

     >ttribute values must always be 0uoted. Eiter single or double 0uotes can be used. 9or a persons sex, te person element can be written like tis'

    +person sexA7female7

    or like tis'

    +person sexAfemale

    1f te attribute value itself contains double 0uotes you can use single 0uotes, like in tisexample'

    +gangster nameAFeorge 74otgun7 Jiegler

    or you can use caracter entities'

    +gangster nameA7Feorge 0uotI4otgun0uotI Jiegler7

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    XML -$e%ents !s& Attributes

    Take a look at tese examples'

    +person sexA7female7

      +firstname>nna+-firstname  +lastname4mit+-lastname+-person

    +person  +sexfemale+-sex  +firstname>nna+-firstname  +lastname4mit+-lastname+-person

    1n te first example sex is an attribute. 1n te last, sex is an element. 2ot examples

    provide te same information.

    Tere are no rules about wen to use attributes or wen to use elements. >ttributes areandy in HTML. 1n XML my advice is to avoid tem. =se elements instead.

    My 2a!orite Way

    Te following tree XML documents contain exactly te same information'

     > date attribute is used in te first example'

    +note dateA78:-:8-G:: date element is used in te second example'

    +note  +date8:-:8-G::

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     >n expanded date element is used in te tird' 5TH14 14 M! 9>K)&1TE6'

    +note  +date  +day8:+-day

      +mont:8+-mont  +yearG:: 7#ell 9ormed7 XML document as corrects XML syntax.

    Te syntax rules were described in te previous capters'

    • XML documents must ave a root element

    • XML elements must ave a closing tag

    • XML tags are case sensitive

    • XML elements must be properly nested

    • XML attribute values must be 0uoted

    +@xml versionA78.:7 encodingA714)"

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    /a$id XML Docu%ents

     > 7Kalid7 XML document is a 7#ell 9ormed7 XML document, wic also conforms to terules of a (ocument Type (efinition 5(T(6'

    +@xml versionA78.:7 encodingA714)"

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      +xs'element nameA7body7 typeA7xs'string7-  +-xs'se0uence+-xs'complexType+-xs'element

    A 3enera$ XML /a$idator 

    To elp you ceck te syntax of your XML files, we ave created an XML validator tosyntax"ceck your XML.

    /a$idate Your XML Against a DTD

    1f you know (T(, and you run 1nternet Explorer, you can validate your XML in te textarea below.

    *ust add te ()%T!?E declaration to your XML and click te 7Kalidate7 button'

    +@xml versionA78.:7 @

    +/()%T!?E note

      +/ELEMET note 5to,from,eading,body6

      +/ELEMET to 5?%(>T>6

      +/ELEMET from 5?%(>T>6

      +/ELEMET eading 5?%(>T>6

      +/ELEMET body 5?%(>T>6

    N

    +note

    +toTove+-to

    +from*ani+-from

    +eading&eminder+-eading

    +message(ont forget me tis weekend/+-message

    +-note

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    XML Na%es#aces

    XML amespaces provide a metod to avoid element name conflicts.

    Na%e )onf$icts

    1n XML, element names are defined by te developer. Tis often results in a conflictwen trying to mix XML documents from different XML applications.

    Tis XML carries HTML table information'

    Na%e )onf$icts

    1n XML, element names are defined by te developer. Tis often results in a conflictwen trying to mix XML documents from different XML applications.

    Tis XML carries HTML table information'

    +table  +tr  +td>pples+-td  +td2ananas+-td  +-tr+-table

    This XML carries infor%ation about a tab$e 4a #iece of furniture5.

    +table  +name>frican %offee Table+-name  +widtn XML parser will not know ow to andle tese differences.

    *o$!ing the Na%e )onf$ict 6sing a +refix

    ame conflicts in XML can easily be avoided using a name prefix.

    Tis XML carries information about an HTML table, and a piece of furniture'

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    +'table  +'tr  +'td>pples+-'td  +'td2ananas+-'td  +-'tr

    +-'table

    +f'table  +f'name>frican %offee Table+-f'name  +f'widtfrican %offee Table+-f'name  +f'widt

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    amespaces can be declared in te elements were tey are used or in te XML rootelement'

    +rootxmlns'A7ttp'--www.w$.org-T&-tmlC-7

    xmlns'fA7ttp'--www.w$scools.com-furniture7

    +'table  +'tr  +'td>pples+-'td  +'td2ananas+-'td  +-'tr+-'table

    +f'table  +f'name>frican %offee Table+-f'name

      +f'widt 6nifor% "esource dentifier  5=&16 is a string of caracters wic identifies an1nternet &esource.

    Te most common =&1 is te 6nifor% "esource Locator  5=&L6 wic identifies an1nternet domain address. >noter, not so common type of =&1 is te 6ni!ersa$"esource Na%e 5=&6.

    1n our examples we will only use =&Ls.

    Defau$t Na%es#aces

    (efining a default namespace for an element saves us from using prefixes in all tecild elements. 1t as te following syntax'

    xmlnsA7namespaceURI 7

    Tis XML carries HTML table information'

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    +table xmlnsA7ttp'--www.w$.org-T&-tmlC-7  +tr  +td>pples+-td  +td2ananas+-td  +-tr

    +-table

    Tis XML carries information about a piece of furniture'

    +table xmlnsA7ttp'--www.w$scools.com-furniture7  +name>frican %offee Table+-name  +widt

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    Te basic #eb services platform is XML O HTT?.

    XML provides a language wic can be used between different platforms andprogramming languages and still express complex messages and functions.

    Te HTT? protocol is te most used 1nternet protocol.

    #eb services platform elements'

    • 4)>? 54imple )b3ect >ccess ?rotocol6

    • =((1 5=niversal (escription, (iscovery and 1ntegration6

    • #4(L 5#eb 4ervices (escription Language6

    #eb 4ervices ave Two Types of =ses

    "eusab$e a##$ication'co%#onents&

    Tere are tings applications needs very often. 4o wy make tese over and overagain@

    #eb services can offer application"components like' currency conversion, weaterreports, or even language translation as services.

    )onnect existing software&

    #eb services can elp to solve te interoperability problem by giving differentapplications a way to link teir data.

    #it #eb services you can excange data between different applications and differentplatforms.

    #eb 4ervices ave tree basic platform elements' 4)>?, #4(L and =((1.

    #eb 4ervices ave tree basic platform elements' 4)>?, #4(L and =((1.

    #at is 4)>?@

    4)>? is an XML"based protocol to let applications excange information over HTT?.

    )r simpler' 4)>? is a protocol for accessing a #eb 4ervice.

    • 4)>? stands for 4imple )b3ect >ccess ?rotocol

    • 4)>? is a communication protocol

    • 4)>? is a format for sending messages

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    • 4)>? is designed to communicate via 1nternet

    • 4)>? is platform independent

    • 4)>? is language independent

    • 4)>? is based on XML

    • 4)>? is simple and extensible

    • 4)>? allows you to get around firewalls

    • 4)>? is a #$% standard

    #at is #4(L@

    #4(L is an XML"based language for locating and describing #eb services.

    • #4(L stands for #eb 4ervices (escription Language• #4(L is based on XML

    • #4(L is used to describe #eb services

    • #4(L is used to locate #eb services

    • #4(L is a #$% standard

    #at is =((1@

    =((1 is a directory service were companies can register and searc for #eb services.

    • =((1 stands for =niversal (escription, (iscovery and 1ntegration

    • =((1 is a directory for storing information about web services

    • =((1 is a directory of web service interfaces described by #4(L

    • =((1 communicates via 4)>?

    • =((1 is built into te Microsoft .ET platform

     >ny application can ave a #eb 4ervice component.

    #eb 4ervices can be created regardless of programming language.

    #eb 4ervices 4ummary

    Tis tutorial as taugt you ow to convert your applications into web"applications.

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    !ou ave learned ow to use XML to send messages between applications.

    !ou ave also learned ow to export a function 5create a web service6 from yourapplication.

    ow !ou Dnow #eb 4ervices, #ats ext@

    Te next step is to learn about #4(L and 4)>?.

    W*DL

    #4(L is an XML"based language for describing #eb services and ow to access tem.

    #4(L describes a web service, along wit te message format and protocol details forte web service.

    *OA+

    4)>? is a simple XML"based protocol tat allows applications to excange informationover HTT?.

    )r more simply' 4)>? is a protocol for accessing a web service.

    W*DL 4Web *er!ices Descri#tion Language5 is an XML'based $anguage for

    describing Web ser!ices and how to access the%

    #4(L is an XML"based language for describing #eb services and ow to access tem.

    W*DL Describes Web *er!ices

    #4(L stands for #eb 4ervices (escription Language.

    #4(L is a document written in XML. Te document describes a #eb service. 1t

    specifies te location of te service and te operations 5or metods6 te serviceexposes.

    #4(L document is 3ust a simple XML document.

    1t contains set of definitions to describe a web service.

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    Te #4(L (ocument 4tructure

     > #4(L document describes a web service using tese ma3or elements'

    -$e%ent Defines

    +types Te data types used by te web service

    +message Te messages used by te web service

    +portType Te operations performed by te web service

    +binding Te communication protocols used by te web service

    Te main structure of a #4(L document looks like tis'

    +definitions

    +types  definition of types........+-types

    +message  definition of a message....+-message

    +portType  definition of a port.......+-portType

    +binding  definition of a binding....+-binding

    +-definitions

     > #4(L document can also contain oter elements, like extension elements, and aservice element tat makes it possible to group togeter te definitions of several webservices in one single #4(L document.

    #4(L ?orts

    Te 7#ortTy#e8 element is te most important #4(L element.

    1t describes a web service, te operations tat can be performed, and te messagestat are involved.

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    Te +portType element can be compared to a function library 5or a module, or a class6in a traditional programming language.

    #4(L Messages

    Te 7%essage8 element defines te data elements of an operation.

    Eac message can consist of one or more parts. Te parts can be compared to teparameters of a function call in a traditional programming language.

    #4(L Types

    Te 7ty#es8 element defines te data types tat are used by te web service.

    9or maximum platform neutrality, #4(L uses XML 4cema syntax to define data types.

    #4(L 2indings

    Te 7binding8 element defines te message format and protocol details for eac port.

    #4(L Example

    Tis is a simplified fraction of a #4(L document'

    +message nameA7getTerm&e0uest7  +part nameA7term7 typeA7xs'string7-+-message

    +message nameA7getTerm&esponse7  +part nameA7value7 typeA7xs'string7-+-message

    +portType nameA7glossaryTerms7  +operation nameA7getTerm7

      +input messageA7getTerm&e0uest7-  +output messageA7getTerm&esponse7-  +-operation+-portType

    1n tis example te 7#ortTy#e8 element defines 7glossaryTerms7 as te name of a#ort, and 7getTerm7 as te name of an o#eration.

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    Te 7getTerm7 operation as an in#ut %essage called 7getTerm&e0uest7 and anout#ut %essage called 7getTerm&esponse7.

    Te 7%essage8 elements define te #arts of eac message and te associated datatypes.

    %ompared to traditional programming, glossaryTerms is a function library, 7getTerm7 is afunction wit 7getTerm&e0uest7 as te input parameter, and getTerm&esponse as tereturn parameter.

     > #4(L port describes te interfaces 5legal operations6 exposed by a web service.

    #4(L ?orts

    Te 7#ortTy#e8 element is te most important #4(L element.

    1t defines a web ser!ice, te o#erations tat can be performed, and te %essages tat are involved.

    Te port defines te connection point to a web service. 1t can be compared to a functionlibrary 5or a module, or a class6 in a traditional programming language. Eac operationcan be compared to a function in a traditional programming language.

    =niversal (escription, (iscovery and 1ntegration 5=((16 is a directory service were

    businesses can register and searc for #eb services.

    What is 6DD

    =((1 is a platform"independent framework for describing services, discoveringbusinesses, and integrating business services by using te 1nternet.

    • =((1 stands for =niversal (escription, (iscovery and 1ntegration• =((1 is a directory for storing information about web services

    • =((1 is a directory of web service interfaces described by #4(L

    • =((1 communicates via 4)>?

    • =((1 is built into te Microsoft .ET platform

    What is 6DD 9ased On?

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    =((1 uses #orld #ide #eb %onsortium 5#$%6 and 1nternet Engineering Task 9orce51ET96 1nternet standards suc as XML, HTT?, and (4 protocols.

    =((1 uses #4(L to describe interfaces to web services

     >dditionally, cross platform programming features are addressed by adopting 4)>?,known as XML ?rotocol messaging specifications found at te #$% #eb site.

    =((1 2enefits

     >ny industry or businesses of all siPes can benefit from =((1.

    2efore =((1, tere was no 1nternet standard for businesses to reac teir customersand partners wit information about teir products and services. or was tere ametod of ow to integrate into eac oters systems and processes.

    ?roblems te =((1 specification can elp to solve'

    • Making it possible to discover te rigt business from te millions currently online

    • (efining ow to enable commerce once te preferred business is discovered

    • &eacing new customers and increasing access to current customers

    • Expanding offerings and extending market reac

    • 4olving customer"driven need to remove barriers to allow for rapid participation in

    te global 1nternet economy

    (escribing services and business processes programmatically in a single, open,and secure environment

    • How can =((1 be =sed• 1f te industry publised an =((1 standard for fligt rate cecking and

    reservation, airlines could register teir services into an =((1 directory. Travelagencies could ten searc te =((1 directory to find te airlines reservationinterface. #en te interface is found, te travel agency can communicate witte service immediately because it uses a well"defined reservation interface.

    • #o is 4upporting =((1@

    • =((1 is a cross"industry effort driven by all ma3or platform and software

    providers like (ell, 9u3itsu, H?, Hitaci, 12M, 1ntel, Microsoft, )racle, 4>?, and4un, as well as a large community of marketplace operators, and e"businessleaders.

    • )ver GG: companies are members of te =((1 community.

    4)>? Tutorial

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    • 4)>? is a simple XML"based protocol to let applications excange information

    over HTT?.• 1n our 4)>? tutorial, you will learn wat 4)>? is, and ow it uses XML to

    excange information between applications.

    4)>? is a simple XML"based protocol to let applications excange information overHTT?.

    )r more simply' 4)>? is a protocol for accessing a #eb 4ervice.

    #at !ou 4ould >lready Dnow

    2efore you study 4)>? you sould ave a basic understanding of XML and XMLamespaces.

    #at is 4)>?@

    • 4)>? stands for 4imple )b3ect >ccess ?rotocol• 4)>? is a communication protocol

    • 4)>? is for communication between applications

    • 4)>? is a format for sending messages

    • 4)>? communicates via 1nternet

    • 4)>? is platform independent

    • 4)>? is language independent

    • 4)>? is based on XML

    • 4)>? is simple and extensible

    • 4)>? allows you to get around firewalls

    • 4)>? is a #$% recommendation

    4)>? 2uilding 2locks

     > 4)>? message is an ordinary XML document containing te following elements'

    •  >n Envelope element tat identifies te XML document as a 4)>? message

    •  > Header element tat contains eader information

    •  > 2ody element tat contains call and response information

    •  > 9ault element containing errors and status information

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    4yntax &ules

    Here are some important syntax rules'

    •  > 4)>? message M=4T be encoded using XML

     > 4)>? message M=4T use te 4)>? Envelope namespace

    •  > 4)>? message M=4T use te 4)>? Encoding namespace

    •  > 4)>? message must )T contain a (T( reference

    •  > 4)>? message must )T contain XML ?rocessing 1nstructions

    • Te 4)>? Envelope element is te root element of a 4)>? message.

    X4LT

    X4L stands for Extensible 4tyle seet Language, and is a style seet language for XMLdocuments.

    X4LT stands for X4L Transformations. 1n tis tutorial you will learn ow to use X4LT totransform XML documents into oter formats, like XHTML.

    X*L Languages

    1t started wit X4L and ended up wit X4LT, X?at, and X4L"9).

    t *tarted with X*L

    X4L stands for Extensible *tyle seet Language.

    Te #orld #ide #eb %onsortium 5#$%6 started to develop X4L because tere was aneed for an XML"based 4tyle seet Language.

    X*L ' More Than a *ty$e *heet Language

    X4L consists of tree parts'

    • X4LT " a language for transforming XML documents

    • X?at " a language for navigating in XML documents

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    • X4L"9) " a language for formatting XML documents

    X4LT

    X4LT is a language for transforming XML documents into XHTML documents or to oter XML documents.

    X?at is a language for navigating in XML documents.

    What is X*LT?

    • X4LT stands for X4L Transformations

    • X4LT is te most important part of X4L

    • X4LT transforms an XML document into anoter XML document

    • X4LT uses X?at to navigate in XML documents

    • X4LT is a #$% &ecommendation

    X*LT : X*L Transfor%ations

    X4LT is te most important part of X4L.

    X4LT is used to transform an XML document into anoter XML document, or anotertype of document tat is recogniPed by a browser, like HTML and XHTML. ormallyX4LT does tis by transforming eac XML element into an 5X6HTML element.

    #it X4LT you can add-remove elements and attributes to or from te output file. !oucan also rearrange and sort elements, perform tests and make decisions about wicelements to ide and display, and a lot more.

     > common way to describe te transformation process is to say tat X*LT transfor%san XML source'tree into an XML resu$t'tree.

    X*LT 6ses X+ath

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    X4LT uses X?at to find information in an XML document. X?at is used to navigatetroug elements and attributes in XML documents.

    X0uery

    XQuery is to XML wat 4QL is to database tables.

    XQuery was designed to 0uery XML data.

    ntroduction to X0uery

    XQuery is to XML wat 4QL is to database tables.

    XQuery is designed to 0uery XML data " not 3ust XML files, but anyting tat can appear as XML, including databases.