A RequestBatcher is a convenience class that allows RequestFactory operations
to be aggregated over a single tick of the event loop and sent as one HTTP
request. Instances of RequestBatcher are reusable, so they may be used as
application-wide singleton objects or within a particular subsystem or UI.
Subclasses need only to provide the instance of the RequestFactory used by
the application and a method to provide a "default" RequestContext from the
RequestFactory.
public class MyRequestBatcher extends RequestBatcher {
public MyRequestBatcher() {
// MyRequestFactory could also be injected
super(GWT.create(MyRequestFactory.class));
}
protected MyRequestContext createContext(MyRequestFactory factory) {
return factory.myRequestContext();
}
}
A singleton or otherwise scoped instance of RequestBatcher should be injected
into consuming classes. The
RequestContext.fire() and
Request.fire() methods reachable from the RequestContext returned from
get() will not trigger an HTTP request. The
RequestContext.fire(Receiver) and
Request.fire(Receiver) methods will register their associated Receivers as
usual. This allows consuming code to be written that can be used with or
without a RequestBatcher.
When an application uses multiple RequestContext types, the
RequestContext.append(RequestContext) method can be used to chain
multiple RequestContext objects together:
class MyRequestBatcher {
public OtherRequestContext otherContext() {
return get().append(getFactory().otherContext());
}
}