INTERNET PROGRAMMING XML

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1 INTERNET PROGRAMMING XML Software Engineering Branch / 4 th Class Computer Engineering Department University of Technology

2 OUTLINES XML Basic XML Advanced 2

JavaScript to program the behavior of web pages.

3 HTML & CSS & JAVASCRIPT & XML DOCUMENTS HTML to define the content of web pages. CSS to specify the layout of web pages. JavaScript to program the behavior of web pages. AJAX to update parts of a web page, without reloading whole page. XML to carry data. 3

4 ARCHITECTURE OF INTERNET database mysql server-side programming CGI, PHP ASP Perl Java Servlets network Protocols Application client-side programming HTML CSS JavaScript (AJAX) XML 4

data, not to display data XML tags are not predefined.

5 WHAT IS XML? XML stands for extensible Markup Language. XML is a markup language much like HTML XML was designed to describe data, not to display data XML tags are not predefined. You must define your own tags. XML is designed to be selfdescriptive XML is a W3C Recommendation. 5

6 THE DIFFERENCE BETWEEN XML & HTML XML is not a replacement for HTML. XML and HTML were designed with different goals: 1. XML was designed to describe data, with focus on what data is. 2. HTML was designed to display data, with focus on how data looks. HTML is about displaying information, while XML is about carrying information. 6

7 XML DOES NOT DO ANYTHING The following example is a note to Tove, from Jani, stored as XML: <?xml version="1.0" encoding="utf-8"?> <note> <to>tove</to> <from>jani</from> <heading>reminder</heading> <body>don't forget me this weekend!</body> </note> But still, this XML document does not DO anything. It is just information wrapped in tags. Someone must write a piece of software to send, receive or display it. 7

8 WITH XML YOU INVENT YOUR OWN TAGS XML is a complement to HTML. It is important to understand that XML is not a replacement for HTML. In most web applications, XML is used to describe data, while HTML is used to format and display the data. 8

XML DOCUMENTS FORM <root> <child> <subchild>..</subchild> </child> </root> The terms parent, child, and sibling are used to describe the relationships between elements.

9 XML DOCUMENTS FORM <root> <child> <subchild>..</subchild> </child> </root> The terms parent, child, and sibling are used to describe the relationships between elements. Parent elements have children. Children on the same level are called siblings (brothers or sisters). All elements can have text content and attributes (just like in HTML). 9

10 XML DOCUMENTS FORM 10

11 TREE STRUCTURE 11

12 XML SYNTAX All XML Elements Must Have a Closing Tag XML Tags are Case Sensitive <Message>This is incorrect</message> XML Elements Must be Properly Nested <b><i>this text is bold and italic</i></b> XML Documents Must Have a Root Element <root> <child> <subchild>...</subchild> </child> </root> XML Attribute Values Must be Quoted <note date="12/11/2007"> 12

13 XML SYNTAX Entity References <message>if salary < 1000 then</message> Comments in XML  White-space is Preserved in XML 13

14 XML ELEMENTS RULES XML elements must follow these naming rules: 1. Element names are case-sensitive 2. Element names must start with a letter or underscore 3. Element names cannot start with the letters xml (or XML, or Xml, etc) 4. Element names can contain letters, digits, hyphens, underscores, and periods 5. Element names cannot contain spaces 14

15 BEST NAMING PRACTICES Create descriptive names, like this: <person>, <firstname>, <lastname>. Create short and simple names, like this: <book_title> not like this: <the_title_of_the_book>. Avoid "-". If you name something "first-name", some software may think you want to subtract "name" from "first". Avoid ".". If you name something "first.name", some software may think that "name" is a property of the object "first". Avoid ":". Colons are reserved for namespaces (more later). Non-English letters like éòá are perfectly legal in XML, but watch out for problems if your software doesn't support them. 15

16 NAMING STYLES There are no naming styles defined for XML elements. But here are some commonly used: 16

17 XML ATTRIBUTES 17

18 VIEWING XML FILES 18

19 DISPLAYING XML WITH CSS * With CSS (Cascading Style Sheets) you can add display information to an XML document. 19

20 XML JAVASCRIPT x=new XMLHttpRequest(); x.open("get","books.xml",false); x.send(); xmldoc=x.responsexml; 20

21 XML ON THE SERVER XML files are plain text files just like HTML files. XML can easily be stored and generated by a standard web server. 21

22 STORING XML FILES ON THE SERVER XML files can be stored on an Internet server exactly the same way as HTML files. Start Windows Notepad and write the following lines: Save the file on your web server with a proper name like "note.xml". 22

23 GENERATING XML WITH ASP XML can be generated on a server without any installed XML software. To generate an XML response from the server - simply write the following code and save it as an ASP file on the web server: 23

24 GENERATING XML WITH PHP To generate an XML response from the server using PHP, use following code: 24

25 GENERATING XML FROM A DATABASE 25

26 XML IN REAL LIFE Some examples of how XML can be used to exchange information. 26

27 XML IN REAL LIFE 27

28 REFERENCES 28

29 Next Lecture PHP 29

markup language carry data define your own tags self-descriptive W3C Recommendation

markup language carry data define your own tags self-descriptive W3C Recommendation XML intro What is XML? XML stands for EXtensible Markup Language XML is a markup language much like HTML XML was designed to carry data, not to display data XML tags are not predefined. You must define