WebObjects

1
WebObjects

• Matt Aguirre
• Lally Singh

2
What Is It?

• A Java based development platform specifically
  designed for database-backed web applications.

3
What Does It Have?

• Scalability built in load balancing among a
  dynamically configurable set of servers
• Industry standards support JSP/J2EE/JNDI support
  built in
• Multiple client type support Web Browser, Java
  Client Application, XML, SMIL, WAP
• Easy extensibility add new web components for
  immediate reuse.

4
Architectural Overview
5
Architecture In Depth
6
Web Components

• Three Parts
• HTML file
• Bindings file
• Java code
• Embeddable within themselves follows the
  Composite design pattern
• Embeddable within JSP pages
• Communicate to each other Enterprise Objects
  (EOs) through Key-Value coding

7
Example Web Component

• A simple form containing two items a textbox and
  a submit button
• User hits Submit and the name is shown in
  System.out.
• Not very useful

8
The HTML

• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"gt
• ltHTMLgt
• ltHEADgt
• ltMETA NAME"generator" CONTENT"WebObjects
  5"gt
• ltTITLEgtUntitledlt/TITLEgt
• lt/HEADgt
• ltBODY BGCOLORFFFFFFgt
• ltwebobject nameForm1gtSample Form
• ltpgtName ltwebobject nameTextField1gtlt/webo
  bjectgtlt/pgt
• ltpgtltwebobject nameSubmitButton1gtlt/webobje
  ctgtlt/pgt
• lt/webobjectgt
• lt/BODYgt
• lt/HTMLgt

9
The Bindings

• Form1 WOForm
• SubmitButton1 WOSubmitButton
• action submit
• TextField1 WOTextField
• value name

10
The Java File

• public class Main extends WOComponent
• protected String name
• public Main(WOContext context)
• super(context)
• name new String()
• public WOComponent submit()
• System.out.println("name"name)
• return null // default - means we go
  back to same page

11
What Happens?

• When the page is requested, the value for name is
  taken from the Components instance via Key-Value
  Coding
• The page is displayed to the user
• The user types in something into the textbox
• The user hits submit
• WO updates the value of name with what the user
  put in the textbox
• WO then calls Mains submit() method
• submit() prints out the string the user typed in

12
Key Value Coding

• A method to access data in classes without
  relying on their interfaces
• Implemented through the KeyValueCoding Java
  interface
• The default implementation scans through
  reflection.
• Ex to set the key foo, the following will be
  checked in order

1. setFoo() 4. _isFoo
2. _setFoo() 5. foo
3. _foo 6. isFoo