This document discusses different types of components in WebObjects, including standard components, non-synchronizing components, stateless components, and dynamic components. It provides examples of how to implement each type of component by subclassing the appropriate base classes and overriding specific methods. The document also includes information on performance considerations for each type of component and recommendations for when each type should be used.

1. MONTREAL JUNE 30, JULY 1ST AND 2ND 2012
Dynamic Elements
Johann Werner
NUREG GmbH

2. Outline
• What are components
• Different common types
• Dynamic components

3. Components
• reusable pieces of representation + functionality
• WebObjects comes with many
(e.g. WOBody, WORepetition, WOString, …)
• Wonder adds a whole bunch
(e.g. AjaxModalContainer, ERXLocalizedString, …)

4. Components
Component API
Code
Template
Binding declarations
Info file

5. Standard Component
• subclass of WOComponent
• automatic push/pull of binding values
• preserves state

6. Standard Component
Parent Code Template
[…] public class MyString extends WOComponent { <wo:str value="$value" />
<wo:MyString value="Hello World" /> public String value;
[…]
public MyString(WOContext context) {
super(context);
}
}

7. Non-Synchronizing Component
• manual push/pull of binding values
➡ less overhead
• preserves state

8. Non-Synchronizing Component
Parent Code Template
[…] public class MyString extends WOComponent { <wo:str value="$value" />
<wo:MyString value="Hello World" /> public MyString(WOContext context) {
[…] super(context);
}
@Override
public boolean synchronizesVariablesWithBindings() {
return false;
}
public String value() {
return (String) valueForBinding("value");
}
}

9. Non-Synchronizing Component
Parent Code Template
[…] public class MyString extends WOComponent { <wo:str value="$^value" />
<wo:MyString value="Hello World" /> public MyString(WOContext context) {
[…] super(context);
}
@Override
public boolean synchronizesVariablesWithBindings() {
return false;
}
}

10. Stateless Component
• manual push/pull of binding values
➡ less overhead
• no state
• single shared instance*
➡ less memory, fewer Java object-creations

11. Stateless Component
Parent Code Template
[…] public class MyString extends WOComponent { <wo:str value="$^value" />
<wo:MyString value="Hello World" /> public MyString(WOContext context) {
[…] super(context);
}
@Override
public boolean isStateless() {
return true;
}
}

12. Stateless Component
Parent Code Template
[…] public class MyString extends WOComponent { <wo:str value="$^value" />
<wo:MyString value="Hello World" /> private Object myVar;
[…]
public MyString(WOContext context) {
super(context);
}
@Override
public boolean isStateless() {
return false;
}
@Override
public void reset() {
super.reset();
myVar = null;
}
}

13. Dynamic Component
• subclass of WODynamicElement
• no template
➡ less memory, faster
• direct access to bindings (WOAssociation)
• direct access to children elements
• must be thread-safe!

14. Dynamic Component
Parent Code
[…] public class MyString extends WODynamicElement {
<wo:MyString value="Hello World" /> private WOAssociation value;
[…]
public MyString(String name, NSDictionary<String, WOAssociation> associations, WOElement template) {
super(name, associations, template);
value = associations.get("value");
}
@Override
public void appendToResponse(WOResponse response, WOContext context) {
WOComponent component = context.component();
response.appendContentString((String) value.valueInComponent(component));
}
}

15. Demo

16. Demo Results
• The more specialized component class the faster it is
• Stateless and dynamic components create less Java objects

17. When should I use…
Standard components
• for pages, big blocks
Non Synchronizing components
• smaller components that are used often
• binding has
• different name as the variable to hold it
• no variable counterpart

18. When should I use…
Stateless components
• no state necessary
• memory optimization
Dynamic components
• no state necessary
• complex output generation
• access to child elements

19. Component Class Tree
Object
WOElement
WODynamicElement WOHTMLBareString WOComponent
WODynamicGroup AjaxComponent D2WComponent ERXComponent JSComponent
WOHTMLDynamic- D2WStateless- ERXNonSynchronizing-
AjaxDynamicElement
Element Component Component
WOHTMLURLValued- ERXStateless-
WOInput
Element Component

20. Component Class Tree
Object
WOElement
WODynamicElement WOHTMLBareString WOComponent
WODynamicGroup AjaxComponent D2WComponent ERXComponent JSComponent
WOHTMLDynamic- D2WStateless- ERXNonSynchronizing-
AjaxDynamicElement
Element Component Component
WOHTMLURLValued- ERXStateless-
WOInput
Element Component

21. Component Class Tree
Object
ERXLoremIpsum,
ERXWOSwitch, …
WOElement
AjaxHighlight,
ERXWORepetition, …
WODynamicElement WOHTMLBareString WOComponent
AjaxHyperlink, AjaxFunctionLink,
AjaxSubmitButton, … ERXJavaScript, …
WODynamicGroup AjaxComponent D2WComponent ERXComponent JSComponent
WOBody,
WOHTMLDynamic-
WOFrame, …
D2WStateless- ERXNonSynchronizing-
AjaxDynamicElement
Element Component Component
ERXSubmitButton,
WOHTMLURLValued-
WOInput
WOCheckBox, ERXStateless-
…
Element Component

22. Component Class Tree
Object
WOElement
WODynamicElement WOHTMLBareString WOComponent
WODynamicGroup AjaxComponent D2WComponent ERXComponent JSComponent
WOHTMLDynamic- D2WStateless- ERXNonSynchronizing-
ERXDynamicElement
Element Component Component
WOHTMLURLValued- ERXStateless-
AjaxDynamicElement WOInput
Element Component

23. Dynamic Base Classes
• ERXDynamicElement in ERXExtensions
• AjaxDynamicElement in Ajax

24. DEMO

25. Creating Dynamic Element
• extend ERXDynamicElement / AjaxDynamicElement
• appendToResponse
• response.appendContentString(…)
• appendTagAttributeToResponse(response, name, value)
• appendChildrenToResponse(response, context)

26. Creating Dynamic Element
• xxxValueForBinding(name, [default,] component)
• ContextData
• beforeProcessing(context)
• afterProcessing(context)

27. MONTREAL JUNE 30, JULY 1ST AND 2ND 2012
Q&A