Insanity Solution

public void onEdisonProjectUpdated(@Observes EdisonProjectUpdatedEvent e)Developing Vaadin with all the "make-easy" techniques can just hides complexity and in fact drive me insane when something went wrong. Also when all these things from different party plays together - they don't often plays well.

So when I survived one insanity scenario, I record it down to avoid future insanity attach :)

FIRST READ "ENVIRONMENT" to get the environment correct!

latest update, no matter what's said below, @SessionScoped vaadin component don't work well. Use its own UIScoped/ViewScoped, etc., see another part of my note!

CDI View - what's their scope?

When nothing specified:

@CDIView(ViewCat.DEBUG)

public class DebugView extends VerticalLayout implements View{

........

    @Inject

    public DebugView(EdisonDataProvider provider) {

        System.out.println("Debug View Initiated"+this.toString());

Every time the view is navigated to, a new instance is created.

If I change the view to session scoped.

@CDIView(ViewCat.DEBUG)

@SessionScoped

public class DebugView extends VerticalLayout implements View, Serializable{

    ......

    @Inject private EdisonDataProvider dataProvider;

    @PostConstruct

    public void initialize() {

Note when SessionScope is used, the bean will be proxyed, and that means a default (no-argument) constructor must be provided and also for bean in session scope, it muse implements the Serializable interface.

Both somehow works. Until not (read next)

When @CDIView and @Sessioned in conflict

@SessionScoped

@CDIView(ViewCat.RESULT_DEFAULT)

public class DefaultProjectView extends HorizontalSplitPanel implements View{

....

    public DefaultProjectView() {

...

    };

    @PostConstruct

    public void postConstruction() {

...

    }

    @Override

    public void enter(ViewChangeEvent event) {

    }

    public void onClaimSetUpdated(@Observes ClaimSetUpdatedEvent e){

        // nothing

    }

    public void onEdisonProjectUpdated(@Observes EdisonProjectUpdatedEvent e){

        // nothing

    }   

    public void onFocusedClaimSlectedEvent(@Observes FocusedClaimSelectedEvent e) {

        // rightTabSheet.setSelectedTab(singleClaimView);

    }

This is what happened.

First, when "public void onEdisonProjectUpdated(@Observes EdisonProjectUpdatedEvent e)" was not in the code, it works (contents show up);

Then, after I added public "void onEdisonProjectUpdated(@Observes EdisonProjectUpdatedEvent e)", even later removed any code inside it (so made it empty), it no longer work. This is when I was mad but, with past experience, quickly figured out it's the SCOPE!!! SCOPE!!! SCOPE!!! SCOPE!!! SCOPE!!!

What happened is, two instances of the DefaultProjectView was constructed (instead of desired, one, as the case when it works). One was instantiated when navigating to the DefaultProjectView, another was instantiated when fired the event EdisonProjectUpdatedEvent. Interestingly, the first time creating a DefaultProjectView instance (navigate to), a proxy-ed instance was constructed. The second time, a non-proxyed (for observing event). Why? I don't know....

Then again, if I remove @SessionScoped and retain the "void onEdisonProjectUpdated" method, it works again... until another event was observed (and then a new instance created again, not desired).. so still not working

A Complete Study

I'm re-creating yesterday evening's problems and will examine here what works / not works and what's learnt

package com.inno4g.edison.view.debug;

import javax.annotation.PostConstruct;

import javax.enterprise.context.Dependent;

import javax.enterprise.event.Observes;

import javax.inject.Inject;

import com.inno4g.workchamp.cdi.Tag;

import com.inno4g.workchamp.vaadin.command.ActionTriggeredEvent;

import com.vaadin.ui.Button;

import com.vaadin.ui.Label;

import com.vaadin.ui.VerticalLayout;

@Dependent

public class GrowingView extends VerticalLayout {

    public GrowingView() {

        System.out.println("\n@@@@@@@ Initializaing Growing View "+this.toString());

    }

    @Inject @Tag("DEBUGCLICK")

    javax.enterprise.event.Event<ActionTriggeredEvent> event;

    @PostConstruct

    public void initialize() {

        addComponent(new Label("First Label"));

        Button click = new Button("Click me");

        click.addClickListener(button -> {

            System.out.println("\n@@@@@@@ button clicked, about to fire with "+event.toString());

            event.fire(new ActionTriggeredEvent());

        });

    }

    public void onDebugClick(@Observes @Tag("DEBUGCLICK") ActionTriggeredEvent e) {

        System.out.println("\n@@@@@@@ onDebug called, handling with "+this.toString());

        addComponent(new Label("\n@@@@@@@ More Components"));

    }

}

Here's the initial code, noted:

• @Dependent - this would make the example not work as intended (every click something added) because wrong instance is called to handle
• inner lambda click event handler - is the same event object that is injected being used?
• pause at inner lambda - what is "this"?
• onDebugClick - is it called? which object?

Answer to the above through observation:

• @Dependent - yes, as observed, every time after event fired, new instance is initialized and that instance (not on screen) is called to handle the event
• is the same event object? cannot see, just "event object is @Tag Event<ActionTriggeredEvent>", let me adjust code and try again
• pause within lambda - this is "GrowingView (id=1087)", interesting, so lambda is method of the outer class?, that means it is not an anonymous class? needs to read this later
• onDebugClick - surely it's called, every time a new object

Now change "event.toString()" - which does not output object's "id hashcode", to "System.identityHashCode(event)"

• this is most interesting, the event in lambda about to fire are all the same event (because they are with the same view that is on screen with the button), which is also the first event being injected
• later every time the view get instantiated, a new event object is injected. but as the views are never on screen, these event objects are never fired

22:53:33,003 INFO  [stdout] (default task-7) @@@@@@@ Initializaing Growing View com.inno4g.edison.view.debug.GrowingView@2610b1d4

22:53:33,003 INFO  [stdout] (default task-7)

22:53:33,003 INFO  [stdout] (default task-7) @@@@@@@ post construct, event object is 907240411

22:53:37,874 INFO  [stdout] (default task-7)

22:53:37,874 INFO  [stdout] (default task-7) @@@@@@@ onDebug called, handling with com.inno4g.edison.view.debug.GrowingView@2610b1d4

22:53:50,639 INFO  [stdout] (default task-6)

22:53:50,639 INFO  [stdout] (default task-6) @@@@@@@ button clicked, about to fire with 1261421341

22:53:50,640 INFO  [stdout] (default task-6)

22:53:50,640 INFO  [stdout] (default task-6) @@@@@@@ Initializaing Growing View com.inno4g.edison.view.debug.GrowingView@7bb45e19

22:53:50,641 INFO  [stdout] (default task-6)

22:53:50,641 INFO  [stdout] (default task-6) @@@@@@@ post construct, event object is 2004166040

22:53:50,641 INFO  [stdout] (default task-6)

22:53:50,641 INFO  [stdout] (default task-6) @@@@@@@ onDebug called, handling with com.inno4g.edison.view.debug.GrowingView@7bb45e19

22:53:52,128 INFO  [stdout] (default task-8)

22:53:52,128 INFO  [stdout] (default task-8) @@@@@@@ button clicked, about to fire with 1261421341

22:53:52,129 INFO  [stdout] (default task-8)

22:53:52,129 INFO  [stdout] (default task-8) @@@@@@@ Initializaing Growing View com.inno4g.edison.view.debug.GrowingView@2579a0dc

22:53:52,129 INFO  [stdout] (default task-8)

22:53:52,129 INFO  [stdout] (default task-8) @@@@@@@ post construct, event object is 337019672

22:53:52,129 INFO  [stdout] (default task-8)

22:53:52,129 INFO  [stdout] (default task-8) @@@@@@@ onDebug called, handling with com.inno4g.edison.view.debug.GrowingView@2579a0dc

Now change @Dependent to @SessionScoped to see if it should work

@SessionScoped

public class GrowingView extends VerticalLayout implements Serializable {

• Yes it works now, every time handled by the same object which is also the first / only (two) instantiated. interestingly, the other instantiated is its proxy.
• so the previous guessed "vertical layout cannot grow" "cannot update" is just wrong. the fact is, wrong vertical layout is called.
• also the event object being used to fire, is the same being injected

Now add printout "this" inside lamdba

• the same GrowingView object as first / only (two) initialized

One more thing, what's the difference between lambda and anonymous inner class? Try to implement another button which uses an anonymous class as event listener.

        Button click = new Button("Click me handled by lambda");

        System.out.println("\n@@@@@@@ post construct, event object is "+System.identityHashCode(event));

        click.addClickListener(button -> {

            System.out.println("inside lambda - what is this? "+this.toString());

            System.out.println("\n@@@@@@@ button clicked, about to fire with "+System.identityHashCode(event));

            event.fire(new ActionTriggeredEvent());

        });

        addComponent(click);

        Button clickInnerClass = new Button("Click me handled by inner class");

        clickInnerClass.addClickListener(

                new ClickListener() {

                    @Override

                    public void buttonClick(ClickEvent clickEvent) {

                            System.out.println("inside anonymous class - what is this? "+this.toString());

                            System.out.println("\n@@@@@@@ button clicked, about to fire with "+System.identityHashCode(event));

                            event.fire(new ActionTriggeredEvent());

                    }

                }

        );

        addComponent(clickInnerClass);

Above codes have two buttons side by side, one implemented with a lambda expression, the other an inner class. Both works, but they work differently.

Lambda: the click handler is the class instance itself

inside lambda - what is this? com.inno4g.edison.view.debug.GrowingView@18f8fb7

Anonymous class: an instance of the anonymous class, the same instance.

inside anonymous class - what is this? com.inno4g.edison.view.debug.GrowingView$1@4768154c

Wait a minute, confused again. what's exactly a lambda? (NEED TO READ) when I add a line "Object x = null; x.toString(); // intentionally create problem" to intentionally creates a problem, the stack print is:

at com.inno4g.edison.view.debug.GrowingView.lambda$initialize$61446b05$1

Is it a method? inner class? what's that?

CDI / listen / update

I was writing views that was injected into another view (layout) and also observes event that the view should update itself. Everything looks good, no error, no exception, but the view just doesn't update itself on browser.... this drove me crazy for several hours and I even developed a (wrong) theory that the layout does not grow with the view update, so the view in fact updated itself, just the change is hidden.... then, finally, I get it,

the reason is the WRONG SCOPE of that view

I made it @Dependent, and with a @Dependent bean:

• No injected instance of the bean is ever shared between multiple injection points.
• Any instance of the bean injected into an object that is being created by the container is bound to the lifecycle of the newly created object.

That was ok for the purpose of my view - it depends on the view containing it anyway. But when container wants a bean (the view) to handle the event being fired, it did not locate the previously initiated bean, but instantiated a new one. Then the new view is updated - all behind the curtain, and never put to the front.

Solution: make the bean @SessionScoped or have the containing view listen to the event

No, latest update,@SessionScoped vaadin component don't work well. Use its own UIScoped/ViewScoped, etc., see another part of my note!

Deploy Time

Removed class file still in deployed package, sometimes leading confusion (CDI)

Seems restart Eclipse first.

17:51:09,943 INFO [com.vaadin.cdi.internal.ContextDeployer] (ServerService Thread Pool -- 70) 0 beans inheriting from UI discovered!

17:42:49,444 WARNING [com.vaadin.cdi.internal.ContextDeployer] (ServerService Thread Pool -- 61) No Vaadin UI classes with @CDIUI annotation found. Skipping automated deployment of VaadinCDIServlet.

When of course @CDIUI is there. Then the real problem, I found, is deploy directory has no classes.

Solution:

tried project context menu -> Maven -> update project, and it seems ok then... not sure about next time

someone here said he think "WTP don't work well when change things in background (maven build)" so his solution is to avoid using that at all. He uses maven solely with perhaps shell scripts.

Yes, FINALLY I found, after failed EVERYTHING, I need to restart Eclipse. So I agree, "run on server" from Eclipse does not work well with Maven. Use Maven goal.