Access remote service using GWTP Rest Dispatch - google-app-engine

Question

I want to separate packages for UI and backend development of my GWTP app.
Currently my UI access the backend using Rest dispatch configured like this:
bindConstant().annotatedWith(RestApplicationPath.class).to("/MyProject/api");
I want to access remote service using localhost UI (running GWT app using eclipse plugin). I changed the above line to:
bindConstant().annotatedWith(RestApplicationPath.class).to("http://my-app.appspot.com/MyProject/api");
Using this, call successfully reaches server ( I can see this in appengine logs) but UI always gets back status code 0.
What is wrong with above setup? Do I have to do something else to access remote service using GWT ui ?

Answer 1

If you want to have a solution that works both on localhost/App Engine, you'd want to use something like this:
import com.google.gwt.core.client.GWT;
import com.google.gwt.inject.client.AbstractGinModule;
import com.google.inject.Provides;
import com.gwtplatform.dispatch.rest.client.RestApplicationPath;
import com.gwtplatform.dispatch.rest.client.gin.RestDispatchAsyncModule;
public class ServiceModule extends AbstractGinModule {
#Override
protected void configure() {
install(new RestDispatchAsyncModule.Builder().build());
}
#Provides
#RestApplicationPath
String getApplicationPath() {
String baseUrl = GWT.getHostPageBaseURL();
if (baseUrl.endsWith("/")) {
baseUrl = baseUrl.substring(0, baseUrl.length() - 1);
}
return baseUrl + "/MyProject/api";
}
}
The string returned by getApplicationPath will be bound to #RestApplicationPath and used seamlessly by GWTP's RestDispatch.
In your case, the string will resolve to http://localhost:8080/MyProject/api or "http://my-app.appspot.com/MyProject/api" depending on the app running locally or on App Engine.