Stop further execution till rpc completes

[Deepak Singh]

Hi,

I have a requirement, 

// some code here 1

RPC call

// some code here 2

I want to stop any further execution after rpc call till rpc completes. When RPC call is finished, the control should automatically start executing next line of code.

I tried Scheduler class but could get into success.

[Paul Robinson]

There have been lots of people ask this question here. The advice you will get is:
(1) Don't try to do it like that. It's evil.
(2) Embrace asynchrony.

Here's what your code should look like:

// some code here 1

myservice.rpcCall(args, new AsyncCallback<Foo> {
public void onFailure(Throwable t) {}

public void onSuccess(Foo foo) {

// some code here 2
}

});

Paul

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[Jens]

Its not possible to stop execution as RPC requests are async. The only thing you can do is to put your code that has to wait into the onSuccess method of your RPC call.

-- J.

[Deepak Singh]

I am making 2 seperate RPC calls.

 Whichever is finished first, i would add RootPanel.get("id").add(widget) into onSuccess.

I can not add same widgets two times in both onSuccess(). So i am out of mind how to resolve this.

Any logic pls.

On Mon, Aug 1, 2011 at 9:08 PM, Jens <jens.ne...@gmail.com> wrote:

Its not possible to stop execution as RPC requests are async. The only thing you can do is to put your code that has to wait into the onSuccess method of your RPC call.

-- J.

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[Magno Machado]

I think you'll have to do something like this:

public class MyEntryPoin implements EntryPoint {

  private boolean alreadyAddedWidget;

  public void onModuleLoad() {

    alreadyAddedWidget = true;

    MyService service = GWT.create(MyService.class);

    service.someCall(args, new AsyncCallback<Foo>() {

      public void onFailure(Throwable caught) {}

      public void onSuccess(Foo result) {

        if (alreadyAddedWidget)

          return;

        alreadyAddedWidget = true;

        RootPanel.get().add(...);

      }

    }

    service.anotherCall(args, new AsyncCallback<Bar>() {

      public void onFailure(Throwable caught) {}

      public void onSuccess(Bar result) {

        if (alreadyAddedWidget)

          return;

        alreadyAddedWidget = true;

        RootPanel.get().add(...);

      }

    }

  }

}

--
Magno Machado Paulo
http://blog.magnomachado.com.br
http://code.google.com/p/emballo/

[Magno Machado]

>  public void onModuleLoad() {

>    alreadyAddedWidget = true;

Sorry, it should be set to false here

[Alan Chaney]

How about:
    if (!RootPanel.get("id).contains(widget)) {
        RootPanel.get("id").add(widget);

Because of the nature of javascript and web browsers the above call is inherently "thread safe".

HTH

Alan

[Deepak Singh]

There is no contains(widget) available like RootPanel.get("id).contains(widget).

[Alan Chaney]

True its WidgetCollection that has a 'contains' method but a RootPanel.get returns a RootPanel object which is a sub-class of ComplexPanel.

ComplexPanel has a getWidgetIndex methods which return -1 for getWidgetIndex(Widget) and null for getWidgetIndex(HasWidget) when the requested object isn't in the widget list. You can derive your own 'contains' logic from the above.


Its purely a matter of style, but I'd personally prefer to avoid having extra state flags to manipulate and would rather use state that's already in the data of the object in question.


Alan

[Mark]

You could always do the following

boolean alreadyAdded = false;

void addWidget(Widget widget) {
if (!alreadyAdded) {
alreadyAdded = true;
RootPanel.get().add(widget);
}
}

and then call addWidget() in each onSuccess(); first caller wins.