Layered Architecture Used in Software Development
Tags: webdev, programming, productivity, softwarearchitectures
Published: 2023-04-12 20:02:04

## Introduction:
Large-scale applications frequently use the well-liked software design paradigm known as layered architecture. It is a structural layout that separates the system into various levels, each of which is in charge of carrying out particular duties.
Four layers make up the layered architecture: presentation, application, domain, and infrastructure. Each layer interacts with the layers above and below it and has a distinct role to play. As a result of the separation of concerns made possible by the layered architecture, the system is more modular, testable, and maintainable.
The creation of complex applications depends heavily on software architecture. A system's maintainability, scalability, and reliability can all be increased by a well-designed architecture. Layered architecture is one of the most widely used architectural patterns because it effectively isolates concerns and encourages versatility. We will go into great detail on layered architecture in this essay, including its advantages, ways to use it, and recommended practices.
## What is Layered Architecture?
With layered architecture, the system is divided into a number of layers, each of which is responsible for a different task and interacts with the layers above and below it. This design pattern encourages modularity, concern separation, and flexibility, which makes the system simpler to test, maintain, and grow.
Four layers make up the layered architecture: presentation, application, domain, and infrastructure. Each layer is in charge of a certain task and only interacts with the layers directly above and below it. The system becomes more modular and is simpler to test and maintain because to this pattern's ability to clearly separate concerns.
## Presentation Layer
The system's top layer, the presentation layer, is in charge of managing user interactions. It deals with data presentation, user input validation, and user interface. To retrieve and store data, this layer interfaces with the application layer. A desktop application, a mobile application, or a web interface can all be used to implement the presentation layer.
## Application Layer
The application layer serves as a bridge between the presentation and domain layers by sitting between them. It controls data flow between the presentation and domain levels, handles user requests, and executes business logic. Security and permission rules must be implemented at this layer as well. Application layer implementations can take the form of a collection of RESTful web services or a collection of API endpoints.

## Domain Layer
The application's core, the domain layer, houses the entities, business logic, and data access rules. The management of the system's state and the enforcement of business rules are under the purview of this layer. It doesn't interact with the presentation layer and solely talks to the application layer. As a collection of classes, interfaces, and data access objects, the domain layer can be put into practice.
## Infrastructure Layer
The infrastructure layer is the system's lowest layer and is in charge of managing the system's resources, including the file system, database, and network connections. It implements technical concerns like logging, caching, and speed optimization while also providing services to the other layers. Both a collection of libraries and a collection of microservices can be used to implement this tier.
## Advantages of Layered Architecture
### Separation of concerns: 
The system's testing and maintenance are simplified by the layered architecture's obvious concern separation.
### Modularity:
It is simpler to scale and reuse components across several levels and applications since each layer may be built and tested independently of the others.
### Flexibility: 
It is simpler to scale and reuse components across several levels and applications since each layer may be built and tested independently of the others.
### Scalability: 
The infrastructure layer may be easily scaled horizontally by adding additional instances.
### Reusability: 
Because components may be reused between layers and applications, the layered architecture speeds up development and lowers costs.
## Implementation of Layered Architecture
1.	The system-specific requirements determine how the layered architecture pattern should be implemented. The following are some best practices for layered architecture implementation:
2.	Establish distinct roles for each tier. Each layer ought to oversee a certain task and only communicate with layers that are directly above and below it.
3.	Interact between levels using interfaces: It is simpler to build and test each layer independently when there is a clear contract between the layers thanks to interfaces.
4.	Manage dependencies with dependency injection: Separating concerns is possible thanks to dependency injection, which also makes system testing and maintenance simpler.


## Advantages of Layered Architecture:
•	The system is simpler to test and maintain because to its modular design and separation of concerns.
•	It is possible to build and test each layer separately from the others.
•	The infrastructure layer may be easily scaled horizontally by adding additional instances.
•	Component reuse across layers and applications is made possible by the tiered design.
•	Because of the layered architecture, developers may concentrate on their area of expertise, which increases productivity and improves code quality.
## Dis-Advantages of Layered Architecture:
A common software architectural pattern called "layered architecture" divides an application into logical layers, each of which offers a specific set of services and functionalities to the layer above it. While employing a layered design has many benefits, there are a few drawbacks to take into account as well:
### Performance Overhead: 
Due to the additional layers of indirection and abstraction, layered architectures may result in performance overhead. Prior to data being passed to the next layer, each layer must complete its processing, which can cause an increase in latency and a decrease in performance.
### Tight Coupling: 
A layered design can result in close coupling between levels, making it challenging to change or remove individual layers without impacting the system as a whole. This may result in expensive maintenance fees and limited flexibility.
### Scalability Challenges: 
Scalability issues can arise in layered designs, particularly if the layers are not appropriately built to withstand high traffic levels. This issue can be made worse by adding more layers, which will result in further performance and scalability problems.
### Complexity: 
Particularly when the number of layers rises, layered systems can become complex and challenging to comprehend. The system may become difficult to extend and maintain as a result.
### Communication Overhead:
 Particularly when the number of layers rises, layered systems can become complex and challenging to comprehend. The system may become difficult to extend and maintain as a result.
## Conclusion:
The layered architecture is a popular paradigm for software architecture that encourages modularity, scalability, and maintainability while explicitly separating domains. It consists of four layers: infrastructure, presentation, application, and domain. Each layer has a distinct function and only communicates with the layer directly above and below it.