Geraldo,
This dispatching method is independent of the signature of the
implementation. Your caching service class execute method can look like
this:
public <T extends Response> void execute(Action<T> action, final
AsyncCallback<T> cb) {
realService.execute(action, new AsyncCallback<T>() {
public void onFailure(Throwable caught) {
cb.onFailure(caught);
}
public void onSuccess(T result) {
// This is where we would cache the result
cb.onSuccess(result);
// This is where we would fire an event on the bus
}
});
}
The actual caching and bus event generation code can be sensitive to the
subtype of Action being passed in.
HTH
Fred
On Sun, Jul 5, 2009 at 8:39 AM, Geraldo Lopes <[email protected]> wrote:
>
> I've been trying to understand Ray's presentation and want to share
> some doubts hoping for clarification:
>
>
> http://dl.google.com/io/2009/pres/Th_0200_GoogleWebToolkitArchitecture-BestPracticesForArchitectingYourGWTApp.pdf
>
> Considering Page 21
>
> interface Action<T extends Response> { }
>
> interface Response { }
>
> interface ContactsService extends RemoteService {
> <T extends Response> T execute(Action<T> action);
> }
>
> interface ContactsServiceAsync {
> <T extends Response> void execute(Action<T> action,
> AsyncCallback<T> callback);
> }
>
>
> Considering the Tossing the Event Page (46)
>
> public void execute(final UpdateContact update,
> final AsyncCallback<GetContactsResponse> cb) {
> realService.execute(update,
> new AsyncCallback<UpdateContactResponse>() {
> ..
> ..
>
> Observe that the execute method has specialized parameters. If it's
> implementing the ContactsServiceAsync interface it probably has a
>
>
> void execute(Action<T> action, AsyncCallback<T> callback) {
> if (action instanceof UpdateContact)
> execute(UpdateContact(action), (GetContactsResponse)callback);
> else
> if (action instanceof AnotherCommand)
> ..
> ..
> }
>
>
> I've understood the purpose of the code (It's a kind of a manual proxy
> to intercept the calls to the realService and make whatever is
> necessary ,caching, eventbus interaction). That's not the point. My
> doubt is : What is the signature of the class ?
>
> If you see the code of page 58 which is a Mock of the
> ContactsServiceAsync
>
> class MockContactsService implements ContactsServiceAsync {
> Action<?> lastAction;
> AsyncCallback<?> lastCallback;
>
> public <T extends Response> void execute(Action<T> action,
> AsyncCallback<T> callback) {
> lastAction = action;
> lastCallback = callback;
> }
> }
>
> You get the impression of there has to be some mechanism to dispatch
> to the real execute methods because one can't write
>
>
> class CachedBatchingService implements ContactsServiceAsync
>
> public CachedBatchingService(ContactsServiceAsync realService) {
> }
>
> public void execute(final UpdateContact update,
> final AsyncCallback<GetContactsResponse> cb) {
> realService.execute(update,
> new AsyncCallback<UpdateContactResponse>() {
> ..
>
> The compiler demands a method with :
>
> <T extends Response> void execute(Action<T> action,
> AsyncCallback<T> callback);
>
>
> Please be tolerant with my english and my java.
>
> Thanks in advance
>
> Geraldo
>
>
> >
>
--
Fred Sauer
[email protected]
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