xml schema
TRANSCRIPT
XML SCHEMABy D.AKSHAYAIII B.TECH IT-A
WHAT IS XML?Extensible Markup
Language (XML) is a markup language that defines a set of rules for encoding documents in a formatwhich is both human-readable and machine-readable
XML was designed to carry data, not to display data
XML HTML Used to carry data Can create own tags Platform independent and language
independent Tags and attributes are case sensitive &
must be quoted XML elements must be properly nested All XML elements must have a closing
tag XML is used to create new internet
languages. Here are some examples: ◦ WSDL for describing available web services ◦ WAP and WML as markup languages for
handheld devices ◦ RSS languages for news feeds ◦ RDF and OWL for describing resources and
ontology ◦ SMIL for describing multimedia for the web
Used to display dataCant create own tagsNot language
independentTags are not case
sensitive & quotes is not complusory
WHERE AND WHY XML?SCENARIOA web service client or server written in java must convert between its internal representation of data and character strings appropriate for representing the data in a SOAP document(or any kind of doc used for displaying the data in the web)Eg: Currency convertor From dollars : web service has to convert the java double value to represent the amount in string
Contd..What would be the constraints in
this process??Data range decisionValue constraintsUsage of scientific notationPrecision issues and etc..
Solution???XML SCHMEA (XML
VOCABULARY):
It has a definition of collection of standard data types.
It has the range of values that could be used for a particular data type and then datas on how to represent the values
XML SCHEMAWELL FORMED XML DOCUMENTXML with correct syntax is "Well Formed" XML.
XML validated against a DTD is "Valid" XML.
Example for XML Document <?xml version="1.0" encoding="ISO-8859-1"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me! </body></note>
XML ELEMENT & VOCABULARY XML Element An XML element is everything from (including) the
element's start tag to (including) the element's end tag. An element can contain: other elements text attributes Or a mix of all of the above... XML vocabulary XML vocabulary is used to define element and attribute names element content Semantics of elements and attributes Some of the xml vocabularies are XHTML, RSS, XSL, DTD,
and Schema
Xml schema and DTD
DTD SCHEMA Defines the structure with a list
of defined elements in the xml document.
<!DOCTYPE note[<!ELEMENT note (to,from,heading,body)><!ELEMENT to (#PCDATA)><!ELEMENT from (#PCDATA)><!ELEMENT heading (#PCDATA)><!ELEMENT body (#PCDATA)>
]>Extension: .dtdHas only two data types: CDATA & PDATA
It is an alternative to DTD to define the structure of an XML document.
<xs:element name="note"><xs:complexType> <xs:sequence> <xs:element name="to" type="xs:string"/> <xs:element name="from" type="xs:string"/> <xs:element name="heading" type="xs:string"/> <xs:element name="body" type="xs:string"/> </xs:sequence></xs:complexType></xs:element>
This definition file is stored with .xsl extension.
Can have primitive and complex data types.
DATA TYPES IN XML SCHEMA
DATA TYPES
SIMPLE
PRIMITIVE(BUILT-IN) USER DEFINED
COMPLEX
PRIMITIVE(BUILT-IN) USER DEFINED
A quick comparison..SIMPLE DATA TYPEValues are
represented in xml doc by character data
Used to represent individual values
COMPLEX DATA TYPEValues are
represented using mark up.
Used to represent structured data(highly organised).
Built in data type..
Sim
ple
built
in d
ata
type
sThe data types defined by xml schema specification itself are called built-in data types.Eg: <latitude xsi:type=“xsd:decimal”>40.28</latitude>Xsd decimal is a reference to XML schema
Xml schema type is similar to java ‘s primitive types. Except for booleanXML schema types appear as type and message elements.Within types, user defined data types are the building blocks for user-defined types.Within message elements built in types are used to declare data type for an operation parameter or return value.
XML NAMESPACESIt is a collection of element and
attributes names associated with an XML vocabulary. XML Namespaces provide a method to avoid element name conflicts.
doc1• <table>
<tr> <td>Apples</td> <td>Bananas</td> </tr></table>
Doc 2•<table> <name> Coffee Table</name> <width>80</width> <length>120</length></table>
Namespace usage
• <h:table> <h:tr> <h:td>Apples</h:td> <h:td>Bananas</h:td> </h:tr></h:table>
<f:table> <f:name>African Coffee Table</f:name> <f:width>80</f:width> <f:length>120</f:length></f:table>
USER DEFINED TYPES..USER DEFINED SIMPLE
TYPES<simpleType
name=“memberType”><restriction base=“string”> <enumeration value=“platinum”/> <enumeration value=“gold”/></restriction></simpleType>Facets of simple data type: length,minlength,maxlength
USER DEFINED COMPLEX TYPE
<anExchangeValue xsi:type=“ExchangeValues”>
<dollars>1.0</dollars>
<euros>0.7468</euros>
</anExchangeValue>
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