1. MVC in NetBeans
and other modular applications
Jaroslav Tulach

2. Agenda
MVC
DCI
NetBeans APIs
Towards Future
Q/A

3. MVC Architecture Pattern Separating Application
Model knows nothing about the rest
Better maintenance
Separate Input/Output
Mainframes
Web
Controller
knows it all

4. Model/View/Presenter
Variation of MVC
Merged Input/Output
GUI
AJAX & co.
Presenter
business
logic

5. Dialogs & Wizards API Descriptor is model
Notify, Dialog, Wizard descriptors
DialogDisplayer
presenter
Wizards
Iterator, Panel
Internal view
No modularity

6. Actions Action is view enables/disables updates name Editor is model
text
selection
history
Action tight to editor
works with the only model

7. Actions in NetBeans Single action knows nothing about components
slightly different meaning in each
Multiple Components
from various modules
Not really MVC

8. Critique of MVC OOP good for data modeling Where to put operations?
BankAccount & money transfer
operation on account?
asymmetric
all or nothing
transactions
Projection of user mind

9. DCI Scandinavian as different as Simula or Beta Interactions
specify required context
Data
morphed
fed to the context
manipulated by
operations

10. DCI Actions in NetBeans
Action seeks in context
usually some specific interface
enables/disables on its presence
operates on it
TopComponents provide own context
morph themselves to specific interfaces
Selection
system builds Menu, Toolbar
binds actions to selected TopComponent's context

11. DCI in NetBeans Explorer Image viewer Editor Selection
Morphs Selection
to Action's model
Action

12. Lookup “Magical Bag” a place to “fish” for an interface
Adaptable Pattern
an object can “morph” to something else
Supports changes
“swim in and out”
listeners
Type safe

13. Exposing Window State class MyWindow
extends org.openide.windows.TopComponent {
private JEditorPane pane;
public org.openide.util.Lookup getLookup() {
return Lookups.singleton(pane.getDocument()); }

14. Querying import org.openide.util.Utilities;
class MyInsertAction extends AbstractAction {
public void actionPerformed (ActionEvent ev) {
Lookup lkp = Utilities.actionGlobalContext();
Document doc = lkp.lookup (Document.class);
if (doc != null) {
doc.insertString ("Hello world!", null, 0); }

15. Listening Lookup.Result<SomeClass> res;
res = someLookup.lookupResult(SomeClass.class);
res.allItems(); // initialize
res.addLookupListener (new LookupListener() {
public void resultChanged (LookupEvent e) {
for (SomeClass : res.allInstances()) {
  //handler code here }
});

16. Create Own Lookup AbstractLookup + InstanceContent
Lookup whose contents you can manage
Lookups.singleton( Object ) - one item Lookup
Lookups.fixed( Object... ) - unchanging Lookup
Lookups.exclude ( Lookup, Class[] );
ProxyLookup ( Lookup[] otherLookups ) - compose multiple lookups

17. Morphing class MyLazyLookup extends AbstractLookup {
MyTopComponent tc;
protected <T> void beforeLookup(Template<T> t) {
if (t.getType() == OpenCookie.class) {
ic.add(new MorphAsOpenCookie(tc)); }
class MorphAsOpenCookie implements OpenCookie {
public void open() {
// implement “open” on MyTopComponent

18. Actions MVC and Modularity
TopComponent1
module A
TopComponent2
module B
Defined together as MVP
Common
Interface
An Action

19. Context Actions
public class FooAction extends AbstractAction implements LookupListener, ContextAwareAction {
private Lookup context;
Lookup.Result lkpInfo;
public FooAction() {
this(Utilities.actionsGlobalContext()); }
private FooAction(Lookup context) {
this.context = context;
void init() {
Lookup.Template tpl = new Lookup.Template(Whatever.class);
lkpInfo = context.lookup (tpl); lkpInfo.addLookupListener(this); resultChanged(null);
public boolean isEnabled() {
init(); return super.isEnabled();
public Action createContextAwareInstance(Lookup context) {
return new FooAction(context);

20. Into the Future @ActionRegistration( displayName=”Open Action”,
iconBase=”org/.../Open.png” )
public class MyAction extends ActionListener {
private OpenCookie oc;
public MyAction(OpenCookie oc) {
// or other ways to do dependency injection
this.oc = oc; }
public void actionPerformed(ActionEvent ev) {
oc.open();

21. Into the Future II “key” to complete control
@ActionRegistration(
displayName=”Find Action”,
iconBase=”org/.../Open.png”,
key=”find” )
public class MyAction extends ActionListener { }
“key” to complete control
any TopComponent can provide own action
system will delegate, if found
tc.getActionMap().put(“find”, new MyOwnAction());

22. Conclusion MVC view and controller tied to model DCI
morphing & adaptation
Lookup
the way to morph in NetBeans
Actions
define control interfaces
Future is

23. Q&A