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I really do not approach the different features of 2.1 as a whole "MVP" set of things: there's  - RequestFactory and ValueStore (I don't think ValueStore has any real use besides RequestFactory, though I'd be happy to be proved wrong) for a record-oriented client-server communication;  - Cell-based widgets for efficient data-backed lists, trees and tables  - PlaceController as typed layer over History (objects rather than strings, even though it's not yet plumbed to History, which at least proves it can be used without it)  - ActivityManager as an "application controller" (to use the term from the GWT tutorials) on top of PlaceController  - and on top of that, GWT provides some base activities plumbed with RequestFactory  - and finally, though it's not documented at all, EditorSupport which works with UiBinder in a view to generate "data-binding code" (as far as I understood) You're free to use any of them independently of the others.

Databinding is about making two properties in sync. The target property could be a JPA entity, but also another widget property. From a Databinding framework perspective, a JPA entity object of any RPC interface should not be tied to the framework.

The intent is that ValueBox? would also be useful for data binding of plain old client side JavaBeans?, without any need for the Id and Property classes. I can define a ValueBox? interface tied to a set of bean classes and have it move their fields to and from HasValue? instances, enforcing validations in the process. I can set up this binding myself via calls like valueBox.setSubcription(bean, fieldNameString). Or I can GWT.create an EditorSupport? object to make those calls for me (which is why they didn't appear in the sketch).

Re: why re-invent a wheel, we want our new data backed widgets to play very nice in an asynchronous world — I'll tell you what values I want, you push them into me when they show up, and as they get updated. My impression of the existing frameworks is that they don't play naturally in that world.

keeping History management abstracted in it’s own right

the need for Presenters to be capable of responding to History tokens

Presenters are decoupled from token managemen

he generally adopted way of doing things in GWT is to have custom events go through the event bus. In this case, you're talking about "navigation", so maybe the concept of "place" would be better than "just" some custom event. I encourage you to look at gwt-platform, gwt- presenter and other MVP frameworks for GWT, and/or look at the Activity concept from the upcoming GWT 2.1. Using actvities, you'd have an ActivityManager managing your "center". The tree would use the PlaceController.goTo to navigate to a new "place". An ActivityMapper (that you passed to the ActivityManager in the constructor) would map the place to an Activity (a presenter), and the ActivityManager will manage the current Activity for the display it manages, i.e.it will stop() the current activity if its ok (willStop returns true) and then only start the new Activity, which will call the Display back to show its view. The tree would probably also listen to PlaceChangeEvent on the event bus to update the selected item depending on the current place (in case some other component calls the PlaceController.goTo)

Views A key concept of MVP development is that a view is defined by an interface. This allows multiple view implementations based on client characteristics (such as mobile vs. desktop) and also facilitates lightweight unit testing by avoiding the time-consuming GWTTestCase. There is no View interface or class in GWT which views must implement or extend; however, GWT 2.1 introduces an IsWidget interface that is implemented by most Widgets as well as Composite. It is useful for views to extend IsWidget if they do in fact provide a Widget. Here is a simple view from our sample app. public interface GoodbyeView extends IsWidget {    void setName(String goodbyeName);} The corresponding implementation extends Composite, which keeps dependencies on a particular Widget from leaking out. public class GoodbyeViewImpl extends Composite implements GoodbyeView {    SimplePanel viewPanel = new SimplePanel();    Element nameSpan = DOM.createSpan();    public GoodbyeViewImpl() {        viewPanel.getElement().appendChild(nameSpan);        initWidget(viewPanel);    }    @Override    public void setName(String name) {        nameSpan.setInnerText("Good-bye, " + name);    }}

A place in GWT 2.1 is a Java object representing a particular state of the UI. A Place can be converted to and from a URL history token (see GWT's History object) by defining a PlaceTokenizer for each Place, and the PlaceHistoryHandler automatically updates the browser URL corresponding to each Place in your app.

Place

Entity proxies simply extend the EntityProxy interface and use the @ProxyFor annotation to reference the server-side entity being represented. It is not necessary to represent every property and method from the server-side entity in the EntityProxy, only getters and setters for properties that should be exposed to the client. Note that while getId() is shown in this example, most client code will want to refer to EntityProxy.stableId() instead, as the EntityProxyId returned by this method is used throughout RequestFactory-related classes. Also note that the getSupervisor() method returns another proxy class (EmployeeProxy). All client-side code must reference EntityProxy subclasses. RequestFactory automatically converts proxy types to their corresponding entity types on the server.

The kinds of changes to Activities and Places we're contemplating for future versions of GWT are primarily along the lines of using annotations and generators to automate the creation of PlaceTokenizers and ActivityMappers, for example. We're not talking about wholesale replacement, as we strive for API backward compatibility with each release.