The document discusses stateful controllers in Direct To Web (D2W) applications built with WebObjects. It provides background on D2W and how controllers were traditionally implemented using ERDBranchDelegate and NextPageDelegate. Stateful controllers improve upon this by allowing controller classes to be reused across multiple pages while maintaining state between pages. This is done by overriding branchChoicesForContext to programmatically define branch choices and storing necessary objects like the editing context. The document provides examples of how stateful controllers can implement common page flows and interactions through utility methods while keeping code DRY and reusable.

1. D2W Stateful Controllers
Fuego Digital Media QSTP-LLC
Daniel Roy

2. • Using WebObjects since 2004
• Work with government agencies, private companies and various
foundations globally
• Fuego Content Management System & Fuego Frameworks
• Presence in North America and Middle East
Fuego History

4. • 42% of community uses D2W
• “D2W is to WebObjects apps as the assembly line is to automobiles...you
provide customization directions (D2W rules) to the assembly line (D2W) to
build your end products (WOComponent pages).”
• Flow is controlled by delegates that manage the actions and direction of the
application
• Use ERDBranchDelegate to define the actions displayed on the page by rules
or via introspection
Direct To Web

5. The Basics
query select edit save

6. Start/Stop
Confirm
Edit
Confirm
Confirm
saveForLater
Save
Delete
edit
Edit CommentreadyToSubmit*
readyToSubmit*
saveAndSubmit
Submit
delete*
confirmDeletion
approveDeletion
confirm
edit*
List Expense
Claims
select
cancel
Notes:
- Cancel is present on all pages, but only
shown for first.
- Any branches with * are optional
and are shown based on business logic
- Any branches with the same name,
are the same page configuration, but
with different branches
Needs to enter
comment?
NO
Edit Comment
YES
WHAT?
WHAT???
??

7. Back in the day...
• Without Project Wonder, rely on nextPageDelegate and
nextPage for navigation
• nextPageDelegate is checked first, and if found call nextPage()
• without nextPageDelegate, nextPage() is called on the D2WPage
component directly
• Single class between each page

8. Next Page Delegate
D2WPage
NPD
(select)
D2WPage
NPD
(edit)
D2WPage
NPD
(query)
...

9. Plain WebObjects Controller Sample Code
public class ManageUserEditNextPageDelegate implements NextPageDelegate {
public WOComponent nextPage(WOComponent sender) {
NSArray<User> selectedObjects = ((ERDPickPageInterface) sender).selectedObjects();
User currentUser = selectedObjects.get(0);
EditPageInterface epi = (EditPageInterface) D2W.factory().pageForConfigurationNamed("ManageUsers_User_Edit_PC", sender.session());
epi.setNextPageDelegate(new ManageUserSaveNextPageDelegate());
epi.setObject(currentUser);
return (WOComponent) epi;
}
}

10. Enter Project Wonder
• ERDBranchDelegate to the rescue!
• Now you can show multiple branch choices for a page
• Pull choices from D2W context in the method
branchChoicesForContext(), using the D2W rule key
“branchChoices”
• Or, use introspection to find all methods that take a single
WOComponent as parameter

11. ERDBranchDelegate
D2WPage ERDBD
D2WPage
(search)
D2WPage
(add)
D2WPage
(cancel)
ERDBD
D2WPage
(save)
D2WPage
(cancel)
D2WPage
(add)

12. ERDBranchDelegate Sample Code
public class ManageUserControllerSelectBranchDelegate extends ERDBranchDelegate {
// Return an edit page for a single selected row in the pick page
public WOComponent edit(WOComponent sender) {
NSArray<User> selectedObjects = ((ERDPickPageInterface) sender).selectedObjects();
User currentUser = selectedObjects.get(0);
EditPageInterface epi = (EditPageInterface) D2W.factory().pageForConfigurationNamed("ManageUsers_User_Edit_PC", sender.session());
epi.setNextPageDelegate(new ManageUserControllerSaveBranchDelegate());
epi.setObject(currentUser);
return (WOComponent) epi;
}
// From the selected items in the pick page, perform a delete
public WOComponent delete(WOComponent sender) {
NSArray<User> users = ((ERDPickPageInterface) sender).selectedObjects();
for (User user : users) {
user.delete();
}
if (users.count() > 0) {
// Assuming all in same EC.
users.get(0).editingContext().saveChanges();
}
return sender.pageWithName("PageWrapper");
}
}

13. But wait...
• Must still set and get the
objects on each page
• Lots of classes to write
• Why not reuse the same
delegate?

14. Benefits of Delegate Reuse
• Enter the controller/delegate many times (one controller for
many pages)
• Reuse the stored state in editing context
• Support one or many flows within the single class
• Define the visible branches using rules

15. Re-entrant Branch Delegate
D2WPageBD
queryPage
search()
edit()
editPage
selectPage
save()

16. Is ERDBranchDelegate Enough?
• Yes....but...no.
• Branch choices are defined in the rules, but can lead to a
complex ruleset depending on the business logic
• Introspection on the ERDBranchDelegate returns all the
methods in the class

17. Hello (Stateful) World!
• FDStatefulController is a re-entrant branch delegate extending
ERDBranchDelegate
• Better separation of MVC
• Override branchChoicesForContext(D2WContext context)
• Reuse page configurations (define the PC in code)
• store state between pages
• editing context
• EOs, etc in subclasses

18. branchChoicesForContext
public class StatefulController extends ERDBranchDelegate {
private NSArray<?> branches;
private EOEditingContext editingContext;
public NSArray<?> getBranches() {
return branches;
}
public void setBranches(NSArray<?> branches) {
this.branches = branches;
}
public EOEditingContext editingContext() {
if (this.editingContext == null) {
this.editingContext = ERXEC.newEditingContext();
}
return this.editingContext;
}
public NSArray branchChoicesForContext(D2WContext context) {
NSArray choices = getBranches();
if (choices == null) {
branches = (NSArray) context.valueForKey(BRANCH_CHOICES);
} else {
NSMutableArray translatedChoices = new NSMutableArray();
for (Iterator iter = choices.iterator(); iter.hasNext();) {
... rest of method continues the same as ERDBranchDelegate

19. StatefulController Code
// Return an edit page for a single selected row in the pick page
public WOComponent edit(WOComponent sender) {
NSArray<User> selectedObjects = ((ERDPickPageInterface) sender).selectedObjects();
User currentUser = selectedObjects.get(0);
setBranches(new NSArray("save"));
EditPageInterface epi = (EditPageInterface) D2W.factory().pageForConfigurationNamed("ManageUsers_User_Edit_PC", sender.session());
epi.setNextPageDelegate(this);
epi.setObject(currentUser);
return (WOComponent) epi;
}
public WOComponent save(WOComponent sender) {
editingContext().saveChanges();
return sender.pageWithName("PageWrapper");
}
// From the selected items in the pick page, perform a delete
public WOComponent delete(WOComponent sender) {
setBranches(null);
NSArray<User> users = ((ERDPickPageInterface) sender).selectedObjects();
ERXUtilities.deleteObjects(editingContext(), users);
return save(sender);
}

20. Page Utility Methods
Interaction
editPage
queryPage
listPage
inspectPage
messagePage
pickPage
selectPage
Utility
editingContext()
nestedEditingContext
save()

21. Utility Method Examples
protected EditPageInterface editPage(Session session, String pageConfigurationName, EOEnterpriseObject enterpriseObject) {
EditPageInterface epi = (EditPageInterface) pageForConfigurationNamed(pageConfigurationName, session);
epi.setNextPageDelegate(this);
epi.setObject(enterpriseObject);
return epi;
}
protected WOComponent pageForConfigurationNamed(String pageConfigurationName, Session session) {
WOComponent component = D2W.factory().pageForConfigurationNamed(pageConfigurationName, session);
if (component instanceof D2WPage) {
((D2WPage) component).setNextPageDelegate(this);
}
return component;
}

23. Summary
• Re-entrant controller provides code reusability
• Specify branch choices programmatically
• Storing the editing context allows easy access to associated
objects during flows and encourages a single point of save
• Utility and convenience methods allow for simple setup and
development of customized flows

24. Resources
• What is Direct To Web?
http://wiki.wocommunity.org/pages/viewpage.action?pageId=1049018
• D2W Flow Control
http://wiki.wocommunity.org/display/documentation/D2W+Flow+Control
• ERDBranchDelegateInterface
http://jenkins.wocommunity.org/job/Wonder/lastSuccessfulBuild/javadoc/er/directtoweb/pages/
ERD2WPage.html#pageController()
• Page controller in ERD2W
http://osdir.com/ml/web.webobjects.wonder-disc/2006-05/msg00041.html

25. Q&A