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XML Technology

XML Technology. Emerging Importance of XML. HTML-tagging is display oriented. XML-based content tagging has important uses: data mining role-oriented display customization intelligent searching and other value added elements Wide spread industry support for this new open standard

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XML Technology

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  1. XML Technology

  2. Emerging Importance of XML • HTML-tagging is display oriented. • XML-based content tagging has important uses: • data mining • role-oriented display customization • intelligent searching and other value added elements • Wide spread industry support for this new open standard • Microsoft • Netscape • W3C is pushing the standardization efforts • Complementary technology to HTML-based web browsers

  3. Requirements best addressed by XML • Customizing front-end applications - easy presentation of what users want to see • Data mining - ala altavista-type search • Synthesis type applications - combining multiple information sources • Electronic commerce-type applications

  4. XML Markup • Elements and attributes • Entity References • Comments • Processing Instructions • Marked Sections • Document Type Definitions (DTDs)

  5. Elements • Bounded by start and end tags • Sample markup <Patient> <FirstName> Frank</FirstName> <LastName> Foster</LastName> </Patient> • Patient, LastName, FirstName are all entity tags.

  6. Attributes • Name-value pairs included as part of start tags. • Sample markup <APatient patientID=“123” FirstName=“Frank” LastName=“Foster”> <Insurance> Blue Cross </Insurance> <Insurance> HMO </Insurance> </APatient> • FirstName and LastName in the example above are attribute declarations.

  7. XML Aspects • Entity References • used to represent special characters • to include content of external files • to represent blocks of repeated text • to insert unicode characters • to use an entity such as &amp e.g. “O’Reilly &amp; Associates, Inc.” • Comments <!-- this is how a comment starts and ends -->

  8. XML Aspects Continued • Processing Instructions <?name pidata?> where ?name is an application that needs to run and pidata? is parameters that needs to be passed to the application. • CDATA sections • like <PRE> tag in HTML <![CDATA[ unprocessed text goes here….. ]]>

  9. Document Type Definitions • Allows the expression of constraints on tags • Defines sequencing and nesting of tags • Defines attributes and values and defaults • Allows specification of external file references • Four kinds of declarations in XML • Element declarations • Attribute List declarations • Entity declarations • notation declarations

  10. DTD Element Declarations <!Element Patient (FirstName, LastName, Insurance?)> Says that Patient info is composed of FirstName, LastName and optionally Insurance information. <!Element Insurance (#PCDATA)> Says element Insurance is composed of parse-able character data.

  11. DTD Attribute List Declaration <!ATTLIST Apatient patientID ID #required FirstName CDATA LastName CDATA >

  12. Other aspects of DTD • Entity declarations (sort of macro capabilities) • DTDs can be included with the tagged document or referred to externally. • Distinction between “well-formed” and “valid” documents • Well-formed: satisfy XML markue constraints - no associated DTD. • Valid documents: XML markup that adhere to the constraints specified in a DTD.

  13. XML’s evolving family of standards • XML Linking Specification (XLL) • Resource Directory Framework (RDF) • Style sheets • DSSSL - Document Style Semantics and Specification Language • CSS Cascading Style sheets • XSL XML Style Specification Language • Document Object Model • Document Content Descriptors and Schemas

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