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XML. Extensible Markup Language - XML. Meta-Language A language that can be used to create others (vocabularies) Universal Business Language (UBL) Extensible Business Reporting Language (XBRL) Application has sets of xml documents Instance Document .xml contains the data
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Extensible Markup Language - XML • Meta-Language • A language that can be used to create others (vocabularies) • Universal Business Language (UBL) • Extensible Business Reporting Language (XBRL) • Application has sets of xml documents • Instance Document .xml • contains the data • Schema Document .xsd • Describes allowed structure (data types, element names) of instance document • Stylesheet .xsl • Formatting instructions for data in the instance document • All XML documents must be well-formed....
XML Rules – A well formed document The first line of an XML document must contain the prologue. The main theme of the XML document – the root element - must enclose all the other elements in the document. There can be only one root element Every element must have an opening tag <> and a closing tag </> Elements must be properly nested, that is you close the tag that was opened last – think of tags as using a LIFO convention or more properly a LOFC Last Opened First Closed convention (though it doesn’t have quite the same ring to it). Elements can have attributes. Attribute values are enclosed with “ ” and can have no spaces.
XML Concepts Prolog the first line of any XML based document <?xml version="1.0" encoding="UTF-8"?> Element A Tag set (the tag name, its attribute and data) <StudentName campus=“main”>John Smith</StudentName> Element Hierarchy Root Element Contains (or encloses) all the other elements Parent Element Contains other elements Used to represent information about one Instance of an entity For example a customer order Child Element Enclosed by Parent element Represents attributes describing the Parent Element For example: customer name, date of order, items ordered, etc. Attributes used to modify or clarify the data in an element <elevation>130</elevation> <elevation measureUnit = “meter”>130</elevation>
Element Hierarchy <tourGuide> <city> <cityName>Belmopan</cityName> <adminUnit>Cayo</adminUnit> <country>Belize</country> <population>11100</population> <area>5</area> <elevation>130</elevation> <longitude>88.44</longitude> <latitude>17.27</latitude> <description>Belmopan is the capital of Belize</description> <history>Belmopan was established following the devastation of the former capital ,Belize City, by Hurricane Hattie in 1965. High ground and open space influenced the choice and ground-breaking began in 1966. By 1970 most government offices and operations had already moved to the new location. </history> </city> </tourGuide> Root Element Parent Element Child Elements
Root Element The first element tag after the prolog Encloses all other elements UBL defines what the root element name is <Catalogue> </Catalogue>
Parent Elements • Parent elements contain or enclose other elements • Root (<Catalogue> ) Parent of: • <ID> • <Name> • <IssueDate> • <ProviderParty> • <Party> • <PartyName> • <PostalAddress> • <ReceiverParty> • <Party> • <PartyName> • <PostalAddress> • <CatalogueLine> • What are the Parent elements within this element?
Reusable Elements • When possible UBL uses the same structure for elements in different documents • PostalAddress can be used in: • Catalogue • Purchase Order • Invoice • … • So it has the same structure • <StreetName>Main St.</StreetName> <BuildingNumber>56A</BuildingNumber> <CityName>Newark</CityName> <PostalZone>19716</PostalZone> <CountrySubentityCode>DE</CountrySubentityCode> <Country> • <IdentificationCode>USA</IdentificationCode> • </Country>
Element Attributes • Attributes are contained within an opening element tag <> • attributeName=“attribute value” • Name-pair value • <PriceAmount currencyID="USD">575.55</PriceAmount> <BaseQuantity unitCode="UNIT">1</BaseQuantity>
UBL document Rules • Each has a unique Root Element • Each has a required ID • Uniquely Identify document • Each has a required IssueDate • Determine when document is created • Optional IssueTime • Each has two Party elements • Provider/Receiver • Buyer/Seller • Each has at least one line element • CatalogueLine • OrderLine
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Lets Practice: XML Elements Lets look closely at the Catalogue Instance Document http://www.skipwhite.com/Guide2008/Chapter2/CatalogueItemExampleSimple.xml
Prolog and Comment Every XML document starts with a prolog It lets the XML enabled processor that this is an XML document to be processed <?xml version="1.0" encoding="UTF-8"?> Comment <!-- A simplified UBL Catalogue document: SkipWhite.com, April 2008 -->