WHAT THE HELL IS XML?
What the Hell is XML? What the hell is XML? Markup Language Derived from SGML (Standardized General Markup Language) Describes the CONTENT (stylesheet has to be applied to format content) Structured documents, can be used like a database that you can send to your clients/suppliers They can then use the data in any XML-supporting database/app
What the Hell is XML? Like HTML? Both based on SGML Both use tags In both, tags enclose content.. ..content.. In both, tags have attributes..
What the Hell is XML? Like HTML? XML MUST have closing tags This is a paragraph This is invalid in XML MUST have quotation marks around attributes No quotes CaSE senSiTivE! This will not close XML has a strict syntax Documents must be well-formed! XML documents must start with an xml tag..
What the Hell is XML? Object Modelling Irfan Michelle In a database, Apogee would be the database name, Employee would be the Table, Name and Phone would be columns In object models, Employee would be the object, Name and Phone would be Properties
What the Hell is XML? Attributes Irfan Joel Debate over when to use attributes and when to use elements MS XML tends to use attributes by default (faster to process?) Standard XML used elements more
What the Hell is XML? XML – The Rules Document Type Definitions (DTDs) Give the rules for validating documents A bit like a database schema/object model Describes the rules of the structure Relationships between elements (e.g. one to many) Which elements contain which other elements In Backus Naur Form (BNF) – obscure? XML Schemas For a similar purpose to DTDs Are taking over from DTDs Are expressed in XML …
What the Hell is XML? XML – The Rules Referencing a DTD The above is the strict DTD for DHTML (HTML 4)
What the Hell is XML? XML Editors Schema Editors Some allow you to turn a DTD into a schema XML Spy Turbo XML Schema Verifiers Only check the doc is well formed Expat Schema Validator World Wide Web Consortium XML Parser Xerces Java