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.

Author: Fenrizshura Zugami
Country: United Arab Emirates
Language: English (Spanish)
Genre: Relationship
Published (Last): 10 November 2005
Pages: 289
PDF File Size: 3.48 Mb
ePub File Size: 2.62 Mb
ISBN: 697-2-27120-858-8
Downloads: 63651
Price: Free* [*Free Regsitration Required]
Uploader: Taurn

This happens, for example, when selecting a photo in the Photo List view. However, The view can directly invoke functionalities from the model such as checking a value from the database or making a calculation. View transition is directly tied to the history management and is discussed in greater length below.

Mcp presenter will hold the complex application and business logic used to drive UIs and changes to the model. PhotoDetailsView – displays the photo together with title and other data and allows the user to change some of those details. This is not a requirement to have, but suits us well as it creates a basic contract that all our views will adhere to, and that other components are aware of and can trust.

App-wide events are really the only events that you want to be passing around on the Event Bus. So how do we fix this? A more complex model may lead to more data being displayed in a view. Type as well as the handler that should be called when the event is fired. Blindly dumping all of the possible events within your app on the Event Bus can lead to chatty applications that get bogged down in event handling.

That should be as expected as the view is dumb and contains no logic. PhotoListView – displays a list of thumbnail photos and their title PhotoDetailsView – displays the photo together with title and other data and allows the user to change some of those details.

First the MVP model, much like other design patterns, decouples development in a way that allows multiple developers to work simultaneously. We will also make use of an EventBus.


Introduction to the MVP pattern: a GWT example | G-Widgets

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.

These events will be dropped onto the EventBus by the presenters, gwh the AppController will listen tytorial them and react by showing and hiding a busy message. The presentation is probably the clearest in documentation in regards to the new MVP framework, whereas the articles you referenced aren’t quite like the new MVP framework.

Imagine these numbers applied across the board to the hundreds of automated tests that are run on each build. And this brings us to the discussion of those presenters. Model A model encompasses business objects, and in the case of our Contacts application we have: I’m writing this post to see if anyone has solved these issues. Just bwt we jump to the AppController, which is responsible for tying everything together and starting presenters, we want to take a little deeper look at the relationship between presenter and views we have used.

Now that we agree on moving the app logic out of the view, we have to move the view logic out of the presenter. To test my “MVP is best for our project” theory, I did a spike to implement it. This component contains the history management and view transition logic.

The view is completely passive and every interaction of the view with the model is done through the Presenter. Luckily, since most views will be futorial up from a Composite which, from GWT 2.

Building GWT Applications with MVP and Issues with Overlay Types

Thus if user specifies http: Modify presenters and services so a callback can be set that tutoril unit test-friendly. This means it needs to implement the go and bind method from Presenter as well as the onUpdateTitle from PhotoDetailsPresenter.

It handles all events, and context changes. The most common one is to indicate in the browser URL the new view required, usually via a token on the URL, and then to react to that. In our photo application, this means we will have the following three presenters: Stack Overflow works best with JavaScript enabled. While the list of photos is being retrieved, a busy tugorial is displayed to the user. There are two key things to note about this interface. If you can manage to decouple app logic from widget-based code, your unit tests will be much more efficient.


This includes any tables, labels, buttons, textboxes, etc… Views are responsible for the layout of the UI components and have no notion of the model. A light version of the Contact that contains only the unique identifier and display name. The first two chapter examples are the same, except they differ in how views are implemented.

This interface needs to be implemented by the view to allow the Presenter to access components of the view. Multiple developers working simultaneously on the same code base, nvp maintaining legacy features and functionality, can quickly turn into messy code. Building an Tktorial application can be straightforward and easy once you understand the fundamentals behind this design pattern. The other is that all our views will extends the IsWidget interface.

Part 2 of that article has a link to a sample project download. Within the MVP model, we strive to make a view, the component that encompasses the bulk of our code that relies on the DOM and Javascript engine, as small and as simplistic as possible. Instead of “Presenter”, they are called “Activities. To help explain these concepts we will use a simple Contacts application as an example. A promising series of tutorials on GWT 2. This application will allow users to view, edit, and add contacts to a list of contacts that are stored on the server.

All of our views will be implemented as three separate items: Sign up using Facebook. Your links aren’t about that.

Below is an example of the event that is fired upon successfully updating a contact.

Author: admin