Group items tagged

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

It however clarify things about how Google sees MVP in GWT. They're even adding some MVP "framework" to GWT 2.1 (IsWidget and Activities, where an Activity is more or less your presenter, from what I understood).

RequestFactory on the other hand is a new thing for efficient CRUD operations on entity objects, which plugs more-or-less directly into the new Data widgets. Those widgets do blur the line a bit, but they're not really about presentation "logic", and they're somehow MVP- based themselves.

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.

> is so called REST like URLs possible ? /employees/1 This is no more or less "REST like" than the above (I assure you!); and yes it's possible (the issues then are to identify objects that are not yet persisted to the server; and of course mapping the "employees" to an EntityProxy class, representing the class+id couple in the Place, and having dedicated "find" methods to retrieve the object from the server, as without an EntityProxyId you won't be able to use RequestFactory.find()) > does it mean we have to write custom getPlace, getToken, to convert > tokens to places ? Yes. That or writing your own PlaceHistoryMapper that won't use PlaceTokenizer's at all (i.e. implement PlaceHistoryMapper in a concrete class and not use the GWT.create() magic to generate the implementation).