jesus ib's List: SW Development

• In software engineering, multi-tier architecture (often referred to as n-tier architecture) is a client–server architecture in which the presentation, the application processing, and the data management are logically separate processes
• • Comparison with the MVC architecture
• A fundamental rule in a three tier architecture is the client tier never communicates directly with the data tier; in a three-tier model all communication must pass through the middle tier. Conceptually the three-tier architecture is linear. However, the MVC architecture is triangular: the view sends updates to the controller, the controller updates the model, and the view gets updated directly from the model.
• • Web development usage

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• Why is it bad to have lots of logic in the UI layer? The code in the UI layer of an application is very difficult to test without either running the application manually or maintaining ugly UI runner scripts that automate the execution of UI components.
• Notice that there are separate packages for UI and presentation. You might have expected them to be the same, but actually the UI layer of a project should consist only of the various UI elements—forms and controls
• This extra layer is what keeps the display and the logic separate
• In the presentation layer you have the objects that actually implement the behavior for the UI—things like validation display, collection input from the UI
• It's important to note that the presenter has no knowledge of the actual UI layer of the application. It knows it can talk to an interface, but it does not know or care what the implementation of that interface is. This promotes reuse of presenters between disparate UI technologies.
• Test Driven Development (TDD)
• I am making use of a mock object framework called NMock2 that allows me to build mock implementations of interfaces
• Why mocks? A rule of unit testing is to isolate the test as much as possible to focus on one specific object. In this test I am only interested in the expected behavior of the presenter.

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