Design patterns are reusable solutions to common problems in software development. They help you write clean, maintainable, and scalable code that can adapt to changing requirements and contexts. In this article, you will learn how to use design patterns for web, mobile, or cloud applications, and why they are important for teamwork and collaboration.
Web design patterns are solutions to the unique challenges and opportunities of web development, such as user interface, navigation, performance, security, and accessibility. An example of a web design pattern is the Model-View-Controller (MVC), which separates the data (model), the presentation (view), and the logic (controller) of a web application. This makes it simpler to test, debug, and reuse components. The Front Controller pattern centralizes the handling of requests and responses, providing a consistent way to apply common functionality. The Page Object pattern encapsulates the elements and actions of a web page, making it easier to automate testing and avoid code duplication.
The developers and architects must identify the difference between Design Patterns that apply to your objects and the Architectural Patterns that apply to how your application is structured. Design patterns generally apply to the classes/objects and dictates a best practice of how the objects should be structured and how they communicate with each other in a common recurring problem statement. Ex. Strategy, Iterator, Composite, Visitor etc. Architectural Patterns, on the other hand, provide solutions and structures in which the application, as a whole, should be structures and how different modules should communicate with each other. They may include Onion or clean architecture, Microservices or Monolith, n-tier, Event Driven etc.
Mobile design patterns are tailored to the specific challenges and opportunities of mobile development, such as limited screen size, touch input, network connectivity, battery life, and device diversity. For example, the Navigation Drawer pattern provides a hidden menu that slides out from the edge of the screen to access different sections of an app without cluttering the interface. Additionally, Lazy Loading delays the loading of data or images until they are needed for improved performance and user experience. Finally, the Observer pattern allows an object to register for notifications from another object, enabling an app to react to changes in data or state.
Mobile design patterns are the tailored toolset for crafting exceptional user experiences in the mobile realm. They recognize and address the constraints that mobile development poses. Take, for instance, the Navigation Drawer pattern, which elegantly solves the issue of limited screen space by offering a hidden, accessible menu that slides out when needed. This minimizes clutter while providing seamless navigation. Lazy Loading is another invaluable pattern in the mobile landscape. By deferring the loading of data or images until they are required, it optimizes performance and conserves precious bandwidth and battery life. This not only enhances user experience but also helps in building efficient, responsive mobile applications.
Cloud design patterns are solutions to the challenges and opportunities that come with cloud development, such as scalability, reliability, availability, security, and cost. For example, the microservices pattern breaks down a complex application into smaller, independent services that each have their own functionality and responsibility. This makes the app easier to scale, deploy, and update. The circuit breaker pattern monitors communication between services and detects failures to prevent cascading errors. The event-driven pattern uses events to trigger actions or responses, decoupling the services and allowing the app to handle asynchronous and distributed processes.
In .NET, We generally use the Nuget package Polly for introducing the Retry or Circuit Breaker Policies. You can create a Policy and provide the details of how many attempts you want to make to a failed service before the Circuit Opens (to prevent further calls to that service) and for how long the Circuit should keep open (Timespan). Then using this Policy Object, you can call the service (API) to apply that policy. AsyncCircuitBreakerPolicy<T> CBPolicy = Policy.HandleResult<Type>(r => (predicate here)) .CircuitBreakerAsync(intRetryAttempts, timespanTime) Predicate can be any condition that identifies failure like response => response.StatusCode>=500
Design patterns are immensely beneficial for teams working on the same or related projects, as they can improve communication and understanding among members. By using a common vocabulary and reference to describe design decisions and solutions, you can increase consistency and quality across the codebase, while avoiding reinventing the wheel or introducing bugs. Moreover, design patterns can facilitate collaboration and integration by modularizing code and reducing dependencies and conflicts among components.
Design patterns are not one-size-fits-all solutions that you can apply blindly to any problem. Before choosing and applying a design pattern, you need to consider the context, the requirements, the trade-offs, and the alternatives. To help you in this process, here are some tips: study and understand the intent, structure, behavior, and consequences of each design pattern; analyze and define the problem you are trying to solve; compare and evaluate different design patterns that could address your problem; and implement and test the chosen design pattern, making sure to refactor and adapt it as necessary.
It takes some studying, understanding and practice to understand the different problems that respective Design Patterns solve. For ex. if you dealing with a Hierarchical data like Trees/Menus or Parent-Child, you may need a Composite design pattern. If you have different algorithms to solve a problem (Sort -> Quick Sort, Merge Sort) and have to choose between them, you may implement Strategy. Similarly, for notification in change of state of an object, you might need Observer. For making two different objects with different interfaces work with each other, you may need an Adapter. If you have a lot of objects which directly communicate with each other, you might want to consider Mediator pattern to reduce their coupling.
Design patterns are a vast and evolving topic, and there are many resources available to help you learn and apply them. One of the most renowned books is Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. This book introduced the concept and terminology of design patterns, and described 23 fundamental patterns for object-oriented software. Another popular resource is Head First Design Patterns by Eric Freeman, Elisabeth Robson, Bert Bates, and Kathy Sierra. This book explains design patterns in a practical and easy-to-understand way, using examples, diagrams, exercises, and puzzles. Additionally, Refactoring Guru is a comprehensive and interactive website that covers design patterns, refactoring, and anti-patterns with examples, diagrams, quizzes, and code samples in different languages.