Architecting your Google Web Toolkit GWT apps with Model View Presenter ( MVP) At its core, MVP is a design pattern that breaks your app up into the. Main Components of GWT MVP. Framework. • Model. – Responsible for holding raw data. – No business logic allowed (just like any model really). • Example. Modular design for large-scale apps, similar to the widely-accepted MVC approach in “normal” Web applications.
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This is not a requirement but makes our lives easier. We will also tutofial use of an EventBus. App-wide events are really the only events that you want to be passing around on the Event Bus.
In the specific presenter interface we wish to declare those methods that will be called from the view when things happen. A light version tutprial the Contact that contains only the unique identifier and display name. You can click gwwt one of the photos, and a larger version is shown on its own, and here you can edit the title through an editable label where the new title is saved back to the server, if requested.
Insight Into a Hybrid Approach. In order for the app to do something meaningful, the presenter is going to need to:.
java – Any tutorials on the official GWT MVP framework? – Stack Overflow
An implementation of the Gwtt pattern. The AppController is also used to instantiate the application. Switching between views is tied to the history management within the presentation layer.
The number and granularity of models is a design decision.
Introduction to the MVP pattern: a GWT example
When UI elements in the view are updated, they notify the presenter to change the model. The view is completely passive and every interaction of the view with the model is done through the Presenter. The only difference between the two versions is the use of UiBinder, and therefore how we bind events to actions. Model A model encompasses business objects, and in the case of our Contacts application we have: In the PhotoListPresenterImpl code, we have:.
Nice words, but what does it mean? However, The tuotrial can directly invoke functionalities from the model such as checking a value from the database or making a calculation.
For example, if we have changed to the situation in figure 2, then the onValueChange method determines that the value detail means it needs to call the doPhotoDetailsDisplay method. Each of our views will be built upon a basic interface that we will call View.
Instead at least mmvp our example appwe pass around events such as a contact being updated, the user switching to the edit view, or an RPC that deleted a user has successfully returned from the server. MVP takes away the intelligence from the View and adds it to the controller which makes a Presenter.
MVP Architecture for GWT Application
Remember that we said the view is responsible for reacting to UI events within itself, but that it will then call methods on the presenter that was registered with it for the actual business logic. By convention, we tend to put all the binding code in a bind method, if we are not using UIBinder.
Figure 3 Development mode URL after photo has been selected to be shown in the detailed view. The general flow, as shown in the following code, is: This method we set up to simply parse the history token to determine what view is requested, and then is required, and will call one of the do methods in 3, if the history token is recognized and an action can be determined.
A log4j-style logger for GWT.
To begin we will break our application up into the following components: This means it needs to implement the go and bind method from Presenter as well as the onUpdateTitle from PhotoDetailsPresenter. Just like views, we will create a basic interface that all of our presenters will implement. Our view specific interfaces detail exactly what can be expected from the view.