The Most Commonly Used Design Patterns in .NET Development | Main- CQRS : Mastering

Design patterns in ASP.NET Core, like in any software development, can be classified into different types based on their purpose and usage. Here are some common types of design patterns used in ASP.NET Core:

i.) Creational Patterns: These patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. Examples include:

• Singleton: Ensures a class has only one instance and provides a global point of access to it.
• Factory Method: Defines an interface for creating objects, but lets subclasses alter the type of objects that will be created.
• Abstract Factory: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
• Builder Pattern: Constructs complex objects step by step. It separates the construction of a complex object from its representation, allowing the same construction process to create different representations.

ii.) Structural Patterns: These patterns deal with object composition, i.e., they help in building large structures of objects. Examples include:

• Adapter: Allows objects with incompatible interfaces to collaborate.
• Decorator: Adds behavior to objects dynamically.
• Facade: Provides a simplified interface to a complex subsystem.
• Bridge Pattern: Decouples an abstraction from its implementation, allowing both to vary independently. It is often used when both the abstraction and its implementation need to be extensible.

iii.) Behavioral Patterns: These patterns are concerned with algorithms and the assignment of responsibilities between objects. Examples include:

• Observer: Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
• Strategy: Defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
• Chain of Responsibility: Avoids coupling the sender of a request to its receiver by giving more than one object a chance to handle the request.
• Command Pattern: Encapsulates a request as an object, allowing for parameterization of clients with different requests, queuing of requests, and logging of requests.
• State Pattern: Allows an object to alter its behavior when its internal state changes, providing a more object-oriented way to manage state-dependent behavior.
• Memento Pattern: Captures and externalizes an object's internal state so that the object can be restored to this state later without violating encapsulation.

iV.) Architectural Patterns: These patterns are at a higher level of abstraction and deal with overall application architecture. Examples include:

• Model-View-Controller (MVC): Separates an application into three main components: Model, View, and Controller.
• Model-View-ViewModel (MVVM): Similar to MVC, but tailored for data binding in client-side applications.

• Dependency Injection (DI): A technique where an object receives its dependencies from an external source rather than creating them itself, promoting loose coupling and easier testing.

• CQRS (Command Query Responsibility Segregation): Separates the read and write operations of a data store into separate paths, improving scalability and performance.
  Repository Pattern: Mediates between the domain and data mapping layers using a collection-like interface for accessing domain objects.
  Advantage:

• Independent Scaling.

• Optimizing Data Transfer object provides separation of
  concern.

• High scalability.

• MediaTr pattern- Mediatr pattern is a behavioral pattern
  that let us reduce dependencies between the object by
  restricting direct communication between the object and the
  forces them to collaborate only via a mediatr object.

• Repository Pattern: Mediates between the domain and data mapping layers using a collection-like interface for accessing domain objects. It provides a more object-oriented way to access data, decoupling the application from the specifics of the data storage implementation.
  -The repository of the service used to access the data from
  the database table.

v.) Other Patterns:

• Circuit Breaker Pattern: Helps in handling faults that might take a variable amount of time to fix when connecting to a remote service or resource, preventing an application from repeatedly trying to execute an operation that's likely to fail.
• Options Pattern: Provides a way to access a set of related configuration settings, allowing for strongly typed access to configuration settings and simplifying the management of configuration data.