N-Tier architecture

N-Tier architecture helps in separating the different concerns of an application. It does this by breaking the application into distinct layers, each with its own responsibilities.

The layers that we usually have are the Presentation Layer, Business Logic Layer, and Data Access Layer. Depending on the complexity of the application, there may be additional layers as well.

These layers can be hosted on separate machines (servers) or can be organized by using proper folder structure within a single machine.

Layers

Presentation Layer - This is the user interface of the application. It could be a page on a website or the UI of a mobile app. Basically, it’s anything the end user can see and interact with.

Business Logic Layer - This is where the core functionality of the application happens. Think of it as the brain of the app. It doesn’t handle how things look or where data is stored, its only job is to make sure the right actions happen according to the business rules.

Data Access Layer - This is the persistence layer, its responsible for storing and retrieving data from the database. Whenever the Business Logic Layer needs to save or query something from database, it has to go through this layer.

The layers are organized so that each layer doesn’t know about its parent layer.

The Business Logic Layer doesn’t care or know who is calling it, it just processes what it’s asked to do. Similarly, the Data Access Layer has no idea who is calling it or where the queried data is being returned to.

Benefits of N-Tier Architecture

Scalability - If layers are hosted on separate machines, it becomes easy to upgrade or add resources to specific layers. For example, if our database is overloaded and we need more space, we can scale or upgrade the Data Access Layer without affecting the other layers.

Flexibility - Each layer can be changed or swapped easily without requiring changes to other layers. For example, if we want to update our Presentation Layer, we can change the entire UI without ever touching the Business Logic Layer.

Maintainability - Different teams can focus only on the layer they are working on, they don’t have to think about the entire system.

Reusability - The Business Logic Layer contains all the rules and processes for how the system should function. This allows us to easily reuse it when creating new applications, ensuring that they follow the same logic and structure.

Security - Different layers can implement different levels of security. Data Access Layer can be protected from direct access by all users, which minimizes the risk of unauthorized access to sensitive data.

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