Fall Semester, 2004
Web App Intro & Some Seaside
© 2004, All Rights Reserved, SDSU & Roger Whitney
San Diego State University -- This page last updated 21-Sep-04
|
|
Emerging Technology
Fall Semester, 2004 Web App Intro & Some Seaside |
|
|---|---|---|
|
© 2004, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 21-Sep-04 |
CS 683 Emerging Technologies Fall Semester, 2004 Doc 11 Web App Intro & Some Seaside
Session & Database Storage of Transaction state
Copyright ©, All rights reserved. 2004 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent ( http://www.opencontent.org/opl.shtml) license defines the copyright on this document.
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 2 |
1. In Seaside WAHtmlRenderer and its parent class WAAbstractHtmlBuilder contain methods to generate html pages. Find the methods that generate the common html elements like p, h1, h2, table, div, form, input, button, textarea, ul and li.
2. In Seaside create a web app with the root component Seaside.WAAllTests. That application displays a number of tabs, each tab a different example. Look at the examples “Input”, “Html”, “Error”, “Exception” and “Callbacks”. Find the classes used by those examples and make sure you understand how they work.
Seaside – A Multiple Control Flow Web Application Framework, Ducasse, Lienhard, Renggli, ESUG, Sept 6-10, 2004
http://www.iam.unibe.ch/~scg/Archive/Papers/Duca04eSeaside.pdf
Seaside Source code
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 3 |
All requests from Web Browser repeat this process
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 4 |
Common ways to dynamically generate web pages
Web request is passed to a program
VeryBasicServlet>>doGet: aRequest response: aResponse
aResponse write: '<HTML><BODY>
Hello world</BODY></HTML>'.
Code is embedded in html pages
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<title>Hi</title>
</head>
<body>
<% response write: 'Hello World'. %>
</body>
</html>
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 5 |
Information (state) from one page must be saved for next page
Information can be stored in
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 6 |
Data is stored by client
Server can forget about client
<form action="fooBar" method="post" name="Sample"> <input type="hidden" name="name" value="Whitney"> <input type="hidden" name="cart" value="world peace"> <input type="text" name="Credit Card Number" size="40"> <input type="submit" name="submit"> </form> <a href="bar/foo/index.html" title="Help information">Help</a>
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 7 |
Must insure all paths retain data
Pages are coupled
Code depends on order of pages Reduces code reuse
Name clashes
Field names must be different all other pages in transaction
Security Issues
Presentation & domain logic mixed
<form action="fooBar" method="post" name="Sample">
<% response
write: 'input type="hidden" name="name" value="'.
userName ifNotNil: [ response write: userName printString].
response
write: '">';
write: '<input type="hidden" name="cart" value="';
cartItems
do: [:each | response write: each printString]
separatedBy: [response write: ', '].
response
write: '">'.
%>
etc.
</form>
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 8 |
Require session key stored on client side
Store session key in
http://www.amazon.com/exec/obidos/subst/home/home.html/103-0893119-0972637
Go to http://www.amazon.com/ and notice that the url changes and ends in a long number. Now look at all the links on the page and notice that they all contain the same long number.
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 9 |
No overview of Control Flow
Mixing of application & component logic
Difficulty in composing control flows
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 10 |
Smalltalk.Seaside defineClass: #WACounter
superclass: #{Seaside.WAComponent}
instanceVariableNames: 'count '
count ^ count
decrease count := count - 1
increase count := count + 1
initialize self session registerObjectForBacktracking: self. count := 0
renderContentOn: html html heading: count. html anchorWithAction: [self increase] text: '++'. html space. html anchorWithAction: [self decrease] text: '--'
http://bismarck.sdsu.edu/cs683/seaside/go/counter
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 11 |
public class WACounter extends WAComponent {
int count;
increment() { count = count + 1; }
decrement() { count = count - 1; }
renderContentOn(WAHtmlRenderer html) { html.title( “Counter Example”);
html.heading( count);
html.anchorWithAction(increment, “++”);
html.space();
html.anchorWithAction(decrement, “--”);
}
initialize() {
WASession session = session();
session.registerObjectForBacktracking(this);
count = 0;
}
| CS 683 Fall 04 | Doc 11, Web App Intro & Some Seaside Slide # 12 |
Smalltalk.Seaside defineClass: #WAMultiCounter
superclass: #{Seaside.WAComponent}
indexedType: #none
instanceVariableNames: 'counters '
children
^counters
initialize
counters := (1 to: 5) collect: [:i | WACounter new]
renderContentOn: html
counters
do: [:ea | html render: ea]
separatedBy: [html horizontalRule]
http://bismarck.sdsu.edu/cs683/seaside/go/multi
Copyright ©, All rights reserved.
2004 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA.
OpenContent license defines the copyright on this document.