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

http://zdrojak.root.cz/clanky/prezentacni-vzory-zrodiny-mvc/ 4. Model/View/Presenter

Variation of MVC

Merged Input/Output

• GUI

• AJAX & co.

Presenter

• business

• logic

http://zdrojak.root.cz/clanky/prezentacni-vzory-zrodiny-mvc/ 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 requiredcontext

Data

• morphed

• fed to thecontext

• manipulated by

• operations

http://www.artima.com/articles/dci_vision.html 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 NetBeansAction Selection Morphs Selectionto Action's modelEditor ExplorerImageviewer 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 extendsorg.openide.windows.TopComponent{ privateJEditorPane pane; public org.openide.util.Lookup getLookup() { returnLookups.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 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

• Lookupwhose 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 voidbeforeLookup (Template t) {

if (t.getType() == OpenCookie.class) {

ic.add(new MorphAsOpenCookie(tc));

}

}

}

classMorphAsOpenCookie implements OpenCookie {

public void open() {

// implement open on MyTopComponent

}

}

18. Actions MVC and Modularity Defined together as MVPTopComponent1module A An Action CommonInterface TopComponent2module B 19. Context Actions

http://wiki.netbeans.org/wiki/view/DevFaqActionContextSensitive

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) { returnnew FooAction(context); } } 20. Into the Future

@ActionRegistration (

displayName=Open Action,

iconBase=org/.../Open.png

)

public class MyAction extends ActionListener {

private OpenCookie oc;

publicMyAction(OpenCookie oc){

// or other ways to dodependency injection

this.oc = oc;

}

public void actionPerformed(ActionEvent ev) {

oc.open();

}

}

21. Into the Future II

@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 in @annotations

23. Q&A