XML: extensible Markup Language

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1 XML: extensible Markup Language Languages fr web SisInf Lab - Plytechnic University f Bari Master s Degree Curse in Cmputer Engineering

2 What is XML? XML is a subset f SGML aiming t enable generic dcument t be served, received, and prcessed n the Web XML describes a class f data bjects called XML dcuments and partially describes the behavir f cmputer prgrams which prcess them. The main design gals fr XML are: straightfrwardly usable ver the Internet supprt a wide variety f applicatins XML dcuments easy t create easy t write prgrams which prcess XML dcuments human-legible and reasnably clear 1996: develped by the XML Wrking Grup frmed under the auspices f the Wrld Wide Web Cnsrtium (W3C) SinInf Lab Plytechnic University f Bari Languages fr web: XML 2 f 22

3 XML Histry 1986: Standard Generalized Markup Language (SGML) ISO : XML W3C Wrking Draft 1998: XML 1.0, W3C Recmmendatin 2000: XML 1.0 (2nd Editin), W3C Recmmendatin 2004: XML 1.0 (3rd Editin), W3C Recmmendatin 2006: XML 1.1, W3C Recmmendatin 2006: XML 1.0 (4th Editin), W3C Recmmendatin 2006: Namespaces in XML 1.0 (2nd Editin), W3C Recmmendatin 2006: XML 1.1 (2nd Editin), W3C Recmmendatin 2006: Namespaces in XML 1.1 (2nd Editin), W3C Recmmendatin 2008: XML 1.0 (5th Editin), W3C Recmmendatin 2009: Namespaces in XML 1.0 (3rd Editin), W3C Recmmendatin SinInf Lab Plytechnic University f Bari Languages fr web: XML 3 f 22

XML Intrductin markup language designed t stre and transprt data self-descriptive, prlg defines the XML versin and the character encding <?xml versin="1.0" encding="utf-8"?

4 XML Intrductin markup language designed t stre and transprt data self-descriptive, prlg defines the XML versin and the character encding <?xml versin="1.0" encding="utf-8"?> infrmatin wrapped in tags n predefined tags but "invented" by the authr f the XML dcument data stred in plain text frmat simplify data exchange and availability exchanging data between incmpatible systems SinInf Lab Plytechnic University f Bari Languages fr web: XML 4 f 22

5 XML Tree Structure XML dcuments are frmed as element trees tree starts at a rt element and branches frm the rt t child elements all elements can have sub elements (child elements) <rt> <child_1> <subchild_1_1>text</subchild_1_1> </child_1> <child_2> <child_2> </rt> child_1 rt subchild_1_1 subchild_1_2 text text child_2 text SinInf Lab Plytechnic University f Bari Languages fr web: XML 5 f 22

6 XML Elements and Attributes element: everything frm (including) the start tag t (including) the end tag <price>29.99</price> an element can cntain text, attributes, ther elements, a mix f the abve empty element with n cntent <empty/></empty> <empty/> attribute: designed t cntain data related t a specific element <persn gender="female"> </persn> cannt cntain multiple values r tree structures (elements can) nt easily expandable (fr future changes) <nte day="10" mnth="01" year="2008" t="tve" frm="jani" heading="reminder " bdy="dn't frget me this weekend! > </nte> SinInf Lab Plytechnic University f Bari Languages fr web: XML 6 f 22

7 XML Syntax XML prlg ptinal, (if exists) it must cme first in the dcument tree dcuments must have a rt element all XML elements must have a clsing tag tags are case sensitive elements must be prperly nested this is a paragraph OR <empty/> <Message>This is incrrect</message> <message>this is crrect</message> this text is bld and italic this text is bld and italic elements can have quted attributes in name/value pairs ptinal cmments <nte date="12/11/2007"> </nte>  entity references, i.e. characters with special meaning <message>salary < 1000</message> <message>salary < 1000</message> SinInf Lab Plytechnic University f Bari Languages fr web: XML 7 f 22

8 XML Namespace cnflict when mix XML dcuments frm different XML applicatins elements can have different cntent and/r meaning <curses> <curse cfu= 9 >Infrmatin Systems</curse> <curse cfu= 12 >Operating Systems</curse> </curses> <curses> <curse>artificial Intelligence</curse> <curse>languages fr Web</curse> </curses> slving the name cnflict using a prefix qualified name <lif:curses> <lif:curse cfu= 9 >Infrmatin Systems</lif:curse> <lif:curse cfu= 12 >Operating Systems</lif:curse> </lif:curses> <mif:curses> <mif:curse>artificial Intelligence</mif:curse> <mif:curse>languages fr Web</mif:curse> </mif:curses> a namespace fr the prefix must be defined: xmlns:prefix="uri xmlns:lif= xmlns:mif= SinInf Lab Plytechnic University f Bari Languages fr web: XML 8 f 22

9 XML Validatr XML dcument with crrect syntax is called well-frmed (parser, syntax checker) XML dcument validated against a schema is bth well-frmed and valid (validating parser) a schema defines the structure f an XML dcument verify that XML data received frm the utside wrld is valid Schema languages Dcument Type Definitin (DTD) XML Schema Definitin Language (XSD) SinInf Lab Plytechnic University f Bari Languages fr web: XML 9 f 22

10 DTD: Dcument Type Definitin DOCTYPE declaratin used t refer t an external DTD file <?xml versin="1.0" encding="utf-8"?> <!DOCTYPE nte SYSTEM schema.dtd"> <nte> <t>tve</t> <frm>jani</frm> <heading>reminder</heading> <bdy>dn't frget me this weekend!</bdy> </nte> <!DOCTYPE nte [ <!ELEMENT nte (t,frm,heading,bdy)> <!ELEMENT t (#PCDATA)> <!ELEMENT frm (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT bdy (#PCDATA)> ]>!DOCTYPE nte defines that the rt element f the dcument is nte!element nte defines that the nte element must cntain the elements: "t, frm, heading, bdy"!element t defines the t element t be f type "#PCDATA" (parse-able text data)!element frm defines the frm element t be f type "#PCDATA"!ELEMENT heading defines the heading element t be f type "#PCDATA"!ELEMENT bdy defines the bdy element t be f type "#PCDATA" SinInf Lab Plytechnic University f Bari Languages fr web: XML 10 f 22

11 DTD Syntax (1/2) Element: <!ELEMENT element-name cntent-mdel> cntent-mdel EMPTY <!ELEMENT br EMPTY> ANY <!ELEMENT nte ANY> Element cntent <!ELEMENT nte (t,frm,heading,bdy)> Mixed cntent <!ELEMENT nte (#PCDATA e1 e2... en)* > Attribute List: <!ATTLIST element-name attribute-definitins> attribute-type CDATA character data (v1 v2...) list f values ID unique identifier in the dcument IDREF/IDREFS crrespnding t an ID ENTITY shrtcuts t special characters/strings attribute-name attribute-type default-value SinInf Lab Plytechnic University f Bari Languages fr web: XML 11 f 22

DTD Syntax (2/2) default-value ptinal attribute mandatry attribute default value defined value #FIXED value default value NOT defined #IMPLIED #REQUIRED Examples: <!

12 DTD Syntax (2/2) default-value ptinal attribute mandatry attribute default value defined value #FIXED value default value NOT defined #IMPLIED #REQUIRED Examples: <!ATTLIST p align (left center right justify) #IMPLIED> <!ATTLIST recipe id ID #REQUIRED > <!ATTLIST html xmlns CDATA #FIXED <!ATTLIST frm actin CDATA #REQUIRED nsubmit CDATA #IMPLIED methd (get pst) "get" Enctype CDATA "applicatin/x-www-frm-urlencded" > SinInf Lab Plytechnic University f Bari Languages fr web: XML 12 f 22

13 XSD: XML Schema Definitin describes the structure f an XML dcument (just like a DTD) XML-based alternative t DTD dn't have t learn a new language reuse XML editr and parser mre pwerful, supprt data types and namespaces data types supprt useful t: define restrictins n data validate the crrectness f data cnvert data between different data types <xs:element name="nte"> <xs:cmplextype> <xs:sequence> <xs:element name="t" type="xs:string"/> <xs:element name="frm" type="xs:string"/> <xs:element name="heading" type="xs:string"/> <xs:element name="bdy" type="xs:string"/> </xs:sequence> </xs:cmplextype> </xs:element> <!DOCTYPE nte [ <!ELEMENT nte <!ELEMENT t <!ELEMENT frm <!ELEMENT heading <!ELEMENT bdy ]> (t,frm,heading,bdy)> (#PCDATA)> (#PCDATA)> (#PCDATA)> (#PCDATA)> SinInf Lab Plytechnic University f Bari Languages fr web: XML 13 f 22

14 XML Schema 1.1 XML Schema Definitin Language (XSD) 1.1 Part 1: Structures describing the structure and cnstraining the cntents f XML dcuments extends the capabilities f DTD XML Schema Definitin Language (XSD) 1.1 Part 2: Datatypes defining datatypes t be used in XML Schemas Feature DTD XSD Syntax wn frmat XML Ntatin cmpact verbse Data type simple (PCDATA, CDATA) advanced Namespace nt supprted supprted SinInf Lab Plytechnic University f Bari Languages fr web: XML 14 f 22

15 XSD Syntax <xs:schema> element is the rt element f every XML Schema <xs:schema xmlns:xs=" targetnamespace=" xmlns=" elementfrmdefault="qualified"> xmlns:xs, reference XSD namespace targetnamespace, reference XML namespace fr all bjects defined by the schema xmlns, default XML namespace elementfrmdefault, all elements must be namespace qualified/unqualified an XML dcument refers t an XML Schema as: xmlns:xsi=" xsi:schemalcatin=" nte.xsd" namespace t use XSD path SinInf Lab Plytechnic University f Bari Languages fr web: XML 15 f 22

16 XSD: Simple Elements and Attributes <xs:element name="xxx" type="yyy"/> element name built-in XSD data type Examples: <xs:element name="age" type="xs:integer"/> <xs:element name="datebrn" type="xs:date"/> <xs:element name="clr" type="xs:string" default="red"/> <xs:element name="clr" type="xs:string" fixed="red"/> <xs:attribute name="xxx" type="yyy"/> attribute name built-in XSD data type Examples: <xs:attribute name="lang" type="xs:string" default="en"/> SinInf Lab Plytechnic University f Bari Languages fr web: XML 16 f 22

17 XSD: Simple Types with restrictins used t define acceptable values fr XML elements r attributes restrictins n XML elements are called facets <xs:element name="age"> <xs:simpletype> <xs:restrictin base="xs:integer" > <xs:mininclusive value="0"/> <xs:maxinclusive value="120"/> </xs:restrictin> </xs:simpletype> </xs:element> <xs:element name="car" type="cartype" /> <xs:simpletype name="cartype"> <xs:restrictin base="xs:string"> <xs:enumeratin value="audi"/> <xs:enumeratin value= Mercedes"/> <xs:enumeratin value="bmw"/> </xs:restrictin> </xs:simpletype> SinInf Lab Plytechnic University f Bari Languages fr web: XML 17 f 22

18 XSD: Restrictins fr Datatypes Cnstraint enumeratin Descriptin Defines a list f acceptable values fractindigits Specifies the maximum number f decimal places allwed. Must be equal t r greater than zer length maxexclusive maxinclusive maxlength minexclusive mininclusive minlength pattern ttaldigits whitespace Specifies the exact number f characters r list items allwed. Must be equal t r greater than zer Specifies the upper bunds fr numeric values (the value must be less than this value) Specifies the upper bunds fr numeric values (the value must be less than r equal t this value) Specifies the maximum number f characters r list items allwed. Must be equal t r greater than zer Specifies the lwer bunds fr numeric values (the value must be greater than this value) Specifies the lwer bunds fr numeric values (the value must be greater than r equal t this value) Specifies the minimum number f characters r list items allwed. Must be equal t r greater than zer Defines the exact sequence f characters that are acceptable Specifies the exact number f digits allwed. Must be greater than zer Specifies hw white space (line feeds, tabs, spaces, and carriage returns) is handled SinInf Lab Plytechnic University f Bari Languages fr web: XML 18 f 22

19 XSD: Cmplex Types (1/2) XML element cntaining ther elements and/r attributes fur kinds f cmplex elements: empty elements elements that cntain nly ther elements elements that cntain nly text elements that cntain bth ther elements and text XSD <xs:element name="emplyee"> <xs:cmplextype> <xs:sequence> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> </xs:sequence> </xs:cmplextype> </xs:element> XML <emplyee> <firstname>jhn</firstname> <lastname>smith</lastname> </emplyee> SinInf Lab Plytechnic University f Bari Languages fr web: XML 19 f 22

20 XSD: Cmplex Types (2/2) Cmplex Type XSD XML Empty Elements Only Text Only Mixed Cntent <xs:cmplextype name="prdtype"> <xs:attribute name="prdid" type="xs:psitiveinteger"/> </xs:cmplextype> <xs:cmplextype name="persntype"> <xs:sequence> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> </xs:sequence> </xs:cmplextype> <xs:cmplextype name="shetype"> <xs:simplecntent> <xs:extensin base="xs:integer"> <xs:attribute name="cuntry" type="xs:string" /> </xs:extensin> </xs:simplecntent> </xs:cmplextype> <xs:cmplextype name="lettertype" mixed="true"> <xs:sequence> <xs:element name="name" type="xs:string"/> <xs:element name="rderid" type="xs:psitiveinteger"/> <xs:element name="shipdate" type="xs:date"/> </xs:sequence> </xs:cmplextype> <prduct prdid="1345" /> <persn> <firstname>jhn</firstname> <lastname>smith</lastname> </persn> <shesize cuntry="france"> 35 </shesize> <letter> Dear Mr.<name>Jhn Smith</name>. Yur rder <rderid>1032</rderid> will be shipped n <shipdate> </shipdate>. </letter> SinInf Lab Plytechnic University f Bari Languages fr web: XML 20 f 22

21 XSD Indicatrs Order indicatrs: xs:all any rder xs:chice either ne child element r anther xs:sequence specific rder Occurrence indicatrs: maxoccurs maximum number f times an element can ccur minoccurs minimum number f times an element can ccur <xs:element name="child_name" type="xs:string" maxoccurs="10" minoccurs="0"/> Grup indicatrs: element grup attribute grup <xs:grup name="persngrup"> <xs:sequence> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> <xs:element name="birthday" type="xs:date"/> </xs:sequence> </xs:grup> <xs:grup ref="persngrup"/> <xs:attributegrup name="persnattrgrup > <xs:attribute name="firstname" type="xs:string"/> <xs:attribute name="lastname" type="xs:string"/> <xs:attribute name="birthday" type="xs:date"/> </xs:attributegrup> <xs:attributegrup ref="persnattrgrup"/> SinInf Lab Plytechnic University f Bari Languages fr web: XML 21 f 22

22 XML References W3C XML Specificatin ( Extensible Markup Language (XML) 1.0 (Fifth Editin) W3C Recmmendatin, 26 Nvember Extensible Markup Language (XML) 1.1 (Secnd Editin) W3C Recmmendatin, 16 August XML Schema 1.1 Status Examples frm: SinInf Lab Plytechnic University f Bari Languages fr web: XML 22 f 22

XML extensible Markup Language

XML extensible Markup Language extensible Markup Language Eshcar Hillel Sources: http://www.w3schools.com http://java.sun.com/webservices/jaxp/ learning/tutorial/index.html Tutorial Outline What is? syntax rules Schema Document Object