1. XML: New or Old? XML was not an extention of HTML That already existed! SGML (ISO 8879) XML was a simplification of SGML  80 / 20 rule  (80% of the features can be implemented in 20% of the time!)

2. Web Document Standards ApplicationStandard Based on ConstructionXMLSGML ISO 8879 FormattingXSLDSSSL ISO 10179 LinkingXLinkHyTime ISO 10744 PresentationSMILHyTime ISO 10744 DescriptionRDF-

3. XML Example (Viewed in Notepad) The Language of Science Danzig 5.95 3

4. XML Example (Viewed in IE)

5. XML Components Elements Attributes Entities Declarations Processing Instructions Document Type Definitions (DTDs)

6. XML Components - Elements Elements form a hierarchical decomposition Book Chapter Para

7. XML Components – Element Structure Elements form a tree book chapter para parent child ancestor descendant sibling

8. XML Components - Attributes Attributes label elements book chapter para number=1 number=2 type = info id = xyz

9. Entities contain document fragments Like files, web pages or ‘containers’ XML Components - Entities book chapter para ß

10. XML Components - misc Markup declaration defines entities, elements, attributes, DTDs, comments, marked sections. Processing instructions interpret elements and content DTDs constrain elements, attributes and content. DTDs provide a simple grammar.

11. XML Syntax (1) Elements  surrounded by start and end tags contents of foo element  empty element tag for no data equivalent to  names are case sensitive

12. Element content may be  data  mixed  element only Click here XML Syntax (2) Just text data Text and element data

13. XML Syntax (3) Element recognition  naked angle brackets cannot appear if(3 must appear as if(3 < 4)die("Math bug");…  applies to left angle bracket << right angle bracket >> ampersand &&

14. XML Syntax (4) Attributes  provide extra information Merge with Microsoft tomorrow!  both names and values are case sensitive  values MUST be quoted with " or '

15. XML Syntax (5a) Reserved attribute names  xml:lang Pretentious? Moi ? Surely not!

16. XML Syntax (5b) Reserved attribute names  xml:space ARRRGH!

17. XML Syntax (6) Declarations are surrounded by  entity declarations (in DTD, later)  character data sections  comments Processing instructions by

18. XML Syntax (7) Standard entities  predefined left angle bracket << right angle bracket >> ampersand && apostrophe '&apos; double quote ""  character entities decimal ASCII AA hexadecimal UNICODEéé