Multi-tier Architecture

Multi-tier architecture, also known as n-tier architecture, is a software design pattern that separates an application into multiple layers or tiers, each responsible for specific functionalities. This architectural style enhances modularity, scalability, maintainability, and reusability of software systems.

Src: 

https://www3.rocketsoftware.com/rocketd3/support/documentation/Uniface/10/uniface/aboutUniface/unifaceApps/Three_tier_software_architecture.htm

In a typical multi-tier architecture, the application is divided into three main layers: the presentation layer, the business logic layer, and the data storage layer. Let's explore each layer in more detail:

Presentation Layer (or User Interface Layer):

This layer is responsible for presenting information to users and capturing user inputs. It focuses on the user interface (UI) and interaction with end-users. The presentation layer could include components such as web pages, mobile apps, desktop applications, or any other user-facing interfaces. Its main purpose is to collect user input, display information, and handle user interactions.

Business Logic Layer (or Application Layer):

The business logic layer contains the application's core functionality and implements the business rules and processes. It represents the logical and operational aspects of the application. This layer processes the requests from the presentation layer, performs computations, executes algorithms, and interacts with the data storage layer to retrieve or modify data. It encapsulates the application's rules and ensures the proper execution of business logic.

Data Storage Layer (or Data Access Layer):

The data storage layer handles the persistence and retrieval of data from various data sources such as databases, file systems, or external services. It is responsible for storing, accessing, and managing data. The data storage layer interacts with the underlying data sources, performs database operations like querying, updating, and managing transactions.

In addition to these core layers, there can be additional layers depending on the complexity and specific requirements of the application. For example, an integration layer may be included to handle communication with external systems or services.

The multi-tier architecture promotes separation of concerns, allowing different layers to evolve independently. It enables scalability by distributing the workload across multiple servers or instances, as each layer can be scaled individually. It also facilitates reusability, as the layers can be reused in different applications or scenarios.

Communication between layers typically occurs through well-defined interfaces or APIs. For example, the presentation layer sends requests to the business logic layer, which processes the requests and returns the results. The data storage layer communicates with the business logic layer to fetch or persist data.