What are these concepts and how do they help us in designing software?
As the size and complexity of modern application development processes increase, it becomes necessary to simplify these processes and reduce their complexity. Therefore, the design of application architectures is of great importance. Architectural designs ensure that systems are modular and manageable, allowing the development process to proceed more efficiently and error-free. Additionally, these designs make it easier to maintain and update applications.
In this article, we will focus on popular architectural designs for the Android platform. Model View Controller (MVC), Model View Presenter (MVP), and Model View ViewModel (MVVM) are among the main architectures preferred for developing secure and high-performance Android applications. To better understand which architecture should be chosen, we will examine each one in detail in this blog post.
Before looking at each architecture, let's familiarize ourselves with the terms that make them up.
Model, View, ViewModel, Controller, and Presenter
Before diving into these architectures, let's get to know the building blocks that constitute these terms.
Model: Represents the data source of the application. The model is the component that contains your data and application logic. This can include retrieving and processing data from databases, network operations, or other data sources. The model forms the functional foundation of the application, undertaking the task of operating on the data and sharing this data with other components.
View: Refers to the interface presented to the user and is responsible for the visual representation of the data provided by the model.
ViewModel: Specific to the MVVM model. It is an abstraction of the view layer. It acts as a binder between the View and Model. The ViewModel takes the necessary data from the View and requests this data from the Model for processing.
Controller: Found in the MVC (Model-View-Controller) architecture model. The controller is responsible for managing user inputs and controlling the application flow. It takes requests from the user interface and determines how to respond to them.
Presenter: Belongs to the MVP (Model-View-Presenter) architecture model. It is the main component that manages the interaction between the Model and View. The presenter takes data from the Model, processes this data, and presents it appropriately to the View. Unlike MVC (Model-View-Controller), this architecture envisages a tighter connection between the Presenter and View; that is, it communicates directly with the View, ensuring that the View plays a passive role only related to user interface updates.
Model-View-Controller (MVC)
The MVC architectural model is popular in the field of web applications. In Android, the MVC (Model-View-Controller) architecture is a pattern used in application development that aims to separate different aspects of the application (data processing, user interface, and control logic) from each other.
Model: Represents the data and business logic of the application. The model includes functionalities such as database operations, network requests, or processing data received from the user.
View: Includes the interface elements shown to the user. In Android, this typically includes layout files defined with XML and the Activity or Fragment classes that inflate these layouts. The view captures user interactions and forwards them to the Controller when necessary.
Controller: Acts as a bridge between the Model and View. In Android, the Controller is typically implemented as Activity or Fragment. The controller captures actions from the user, forwards them to the Model for processing, and updates the user interface by transferring the results to the View.
In Android, the MVC architecture can sometimes be difficult to define clearly due to the nature of the platform. This is because Android tends to use UI components (Activities and Fragments) as both Controllers and Views, making the traditional implementation of MVC challenging.
MVP (Model-View-Presenter)
MVP is a variation of the MVC (Model-View-Controller) pattern and works more effectively in event-driven programming environments like Android. Here are the main components of MVP:
Model: Represents the data and business logic of the application. The model includes responsibilities such as database operations, API calls, and processing user data.
View: The interface elements displayed to the user. In Android, the view is typically represented by UI components like Activity or Fragment. The view forwards user interactions to the Presenter and updates the interface according to directives from the Presenter.
Presenter: Acts as an intermediary between the Model and View. The presenter takes user actions from the View, executes the necessary business logic on the Model, and then transfers the results to the View to update the UI.
MVP is popular among Android developers because it prevents Activities and Fragments from being overloaded and allows for better organization of the different layers of the application.
MVVM (Model-View-ViewModel)
MVVM (Model-View-ViewModel) architecture is a design pattern that is especially popular in modern application development environments and is an effective design pattern for Android applications. Unlike MVC and MVP patterns, MVVM offers a more data-binding and UI component-independent approach.
Model: As in all architectures, the model in MVVM represents the data and business logic of the application.
View: Represents the interface visible to the user, similar to other models. However, in MVVM, the view directly receives data flow from the ViewModel through data binding, resulting in less and cleaner code.
ViewModel: The most important part of MVVM, the ViewModel acts as a mediator between the View and Model. Unlike the Presenter in MVP, the ViewModel performs its connection with the View through data binding. This means the View is unaware of the existence of the ViewModel and thus is less dependent.
Conclusion
MVP and MVVM are more advanced architectural models than MVC. In MVP, the presenter is completely abstracted from the View, increasing testability. However, each View requires a presenter, which can be a disadvantage. MVVM provides a modern, efficient, and testable architecture for Android and is especially preferred in large-scale projects or applications with heavy data binding. Therefore, it may be appropriate to choose between MVP and MVVM according to the requirements of the project.
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