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I think the overall idea of activities is that they are short-lived instances, so they're effectively "lazily created" (actually, a new instance is created each time one is needed) and they don't need to be "awoken" because if they're not currently in use they're already "dead" and garbage collected. The ActivityManager (actually its associated ActivityMapper) will decide whether a particular activity is needed (and then instantiate it, possibly going through a GWT.runAsync for code splitting); the activity will listen to events its interested in *during its lifetime* (e.g. whether some object has changed or has been added or deleted, so it can update its view); but when it's done (stopped or cancelled), it's simply thrown away (the event bus passed to the start() method is a ResettableEventBus so all handlers have been automatically unregistered for you, which as a side effect allows the activity to be garbage collected). This is the (AIUI) intended use, but nothing forces you to write such short-lived instances: you can very well use singletons, but then you'll have the additional task of maintaining state between "runs" (start/stop or start/cancel), in which case your activity can listen to events from the event bus after being stopped/cancelled (just use the "real" event bus instead of the ResettableEventBus passed to the start() method); but it won't "ask to be revealed": navigation is handled at another layer, triggered on the PlaceController and handled by ActivityManagers.

your ChatBoxPresenter isn't related to a "place", i.e. it's "awoken" based on a "business event", not a navigation event; and in other words, it's not an Activity: case made. Activities (ActivityManager) is limited in scope to reacting to place changes and navigation (not that you couldn't use the Activity "contract" in other scenarios, such as your "chat box", but the ActivityManager wouldn't be the right tool for the job, you'd have to find/write another "activity manager" for your different use case). In other words: GWT 2.1 Activities won't replace GWTP as a whole (and I believe, as I already said in the past, that it's not its goal either).

Ray Ryan - These posts are right on the money, Thomas. I think you hit the problem with this approach too: you still need nested Place objects, and those are a nuisance to make. E.g., in a master detail you might need to record both the page of the master list that is showing as well as which detail set. Maybe the thing to do is add a CompositePlace to GWT?Sep 14

Ray Ryan - The idea is that parents are an optical illusion. There is an activity that knows how to show lists of things. There is another that knows how to show details. In one arrangement of your app they may be on the screen at the same time. In another (*cough* mobile *cough*), they aren't. They really shouldn't know about each other.Sep 14

the key concept here is that an Activity can be a Presenter but a Presenter is not necessarily an activity.Oct 26DeleteUndo deleteReport spamNot spamRay Ryan - Exactly: not every presenter needs to bother being an activity.Oct

The way we're minimizing code right now, is by creating some useful abstract tokenizers that handle the common use cases (no parameter tokenizer, key-value pair tokenizer). With those there are corresponding abstract tokenizers that handle creating the hashCode and equals methods. Aside from the 1:1 between Place and Activity, which bothers me in principle but may not be a practical concern just yet, it's coming along pretty nicely.

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.

although we can't map a 1-Many relationship between a Place and an Activity, you can in fact map multiple places to the same activity and differentiate between the place with multiple init() methods in the activity.