1. Chapter 2: Well-Formed XML

2. Chapter 2 Objectives How to create SML elements using start- tags and end-tags How to further describe elements with attributes How to declare your document as being XML How to send instructions to applications that are processing the XML document Which characters aren’t allowed in XML – and how to use them in your documents anyway!

3. Parsing XML

4. Tags and Text and Elements, Oh My! John Fitzgerald Johanson Doe is a start-tag is and end-tag John is an element

5. Try It Out Creating a Distribution Process

6. Rules for Elements ❑ Every start-tag must have a matching end-tag, or be a self- closing tag. ❑ Tags can’t overlap; elements must be properly nested. ❑ XML documents can have only one root element. ❑ Element names must obey XML naming conventions. ❑ XML is case sensitive. ❑ XML will keep whitespace in your PCDATA.

7. Rules for Elements Bad Example John Jane Good Example John Jane

8. Rules for Elements Names can start with letters, no numbers After first character, numbers, hyphens and periods are allowed Names can’t contain spaces There are reserved characters like “:” Names can’t start with the letters “xml”, “XML”, or “Xml”, or any other combination No spaces after the “ ” if desired

9. Rules for Elements These are two different elements John

10. Rules for Elements Whitespace stripping takes place in HTML… This is a paragraph. It has a whole bunch of space. …but not in XML Example This is a paragraph. It has a whole Bunch of space. This is a paragraph. It has a whole Bunch of space.

11. Rules for Elements Windows uses both the line feed and the carriage return UNIX uses only line feed XML parsers will convert all Windows “line feed and carriage returns” to just line feed characters to standardize end-of-line logic

12. Rules for Elements This is some XML This is known as extraneous whitespace in the markup.

13. Attributes John Fitzgerald Johansen Doe

14. Why use attributes There is nothing that an attribute can do that an element can’t, but not vice-versa They can be handy for “meta” data Suppose you wanted to include the number of individual orders? They are smaller than elements, but Attributes are unordered Some people just like them

15. Try It Out Adding Attributes to Our Orders

16. Comments John Doe

17. Try It Out Some Comments on Orders

18. Empty Elements John Doe

19. XML Declaration John Doe

20. Try It Out Declaring Our Orders to the World

21. Processing Instructions John Doe

22. Illegal PCDATA Characters 6 is 6

23. Escaping Characters 6 is < 7 & 7 > 6

24. CDATA Sections <![CDATA[ function myFunc() { if(0 < 1 && 1 < 2) alert(“Hello”); } ]]>

25. Try It Out Talking about HTML in XML

26. Errors in XML Errors Violations May recover Continue processing Fatal errors Draconian error handling Not allowed to continue

27. Try It Out Adding Attributes to Our Orders Some Comments to Our Orders Declaring Our Orders To The World An Order To Be Processes Talking About HTML in XML