Layered Architecture of Web Application
- Kusuma Reddy
- Sep 2
- 4 min read
Updated: Sep 2
What is web application?
Web application is a software that runs on web server and we can communicate to it through webbrowser(like chrome,firefox,safari) via internet or intranet(private network used internally by organizations).This works on a client–server architecture where requests are sent from the client to the web server. The server processes the request and then returns the response back to the client.
What is layered architecture?
Layered architecture is a software design pattern where the system is divided into separate layers, and each layer has a distinct function. The layers are stacked on top of one another, and only adjacent layers can communicate.
Why do we need layered architecture?
When developing an application, handling large chunks of code becomes a challenging task. Dividing the application into smaller layers makes it easier to manage, as each layer has its own function and responsibilities. In web application design, multiple layers come into play, which makes development and testing easier and ensures that changes in one layer do not affect the others.
Lets understand more about these layers.
User Interface/Presentation layer
The UI layer and the Presentation layer are not exactly the same, but they are closely related. In most organizations, both are considered as a single layer.
The UI layer is what the user actually sees and interacts with in the application.
When we navigate to any website, the first thing we see is the frontend — web elements such as text boxes, buttons, dropdowns, links, and web page content.
This part is developed using technologies like HTML, CSS, and JavaScript.
The Presentation layer, on the other hand, focuses on:
Data formatting and translation (converting backend raw data into user-friendly information).
UI validations (such as form validations and required fields).
Data serialization (preparing data to be sent across layers).
Connecting with the next layer (API/business logic).
Application Programming Interface Layer
The main function of the API layer is to act as a bridge between the UI layer and the Business Logic layer. It receives requests from the UI and sends formatted responses back to the UI. Web application design enforces that users always communicate via API layer .i.e. no direct access to any layers below API layer.
The API layer works primarily with resources. A resource is a logical representation of an entity, typically exposed through endpoints. An endpoint is a specific URL (Uniform Resource Locator) in an API where a particular resource can be accessed.
Examples:/employees → Access employee data/customers → Access customer data
API Flow:
Request: A user/customer sends a request to the server.
Processing: The server receives and process the request.
Response: The server prepares and generates the requested data.
Delivery: The API forwards the server response to user/customer.
Types of APIs: REST(Representational State Transfer), SOAP(Simple Object Access Protocol) and GraphQL
Business Logic layer
In this layer, business rules and logic is applied. It understands both resources and entities. The main functions of this layer are applying validations, converting entities into user-readable data, and managing the workflow. This layer defines how data can be created, used, and modified.
Key Responsibilities:
Validate the input received from the client side.
Perform required operations on the data.
Apply business rules.
Communicate with the Data Access Layer and API Layer.
Provide security by preventing direct interaction with user.
Manage business workflows.
Technologies used: Java/Spring Boot, .NET and Python etc
Entity/Data Access Layer
These are two different layers in software architecture but are closely related. The Entity Layer deals with the structure of data, such as fields and attributes. For example, if we have an Employee entity, attributes like Employee ID and Name are defined here. The Data Access Layer, on the other hand, is responsible for data manipulations, such as CRUD (Create, Read, Update, Delete) operations, performed on this data.
Why we need this layer?
Developers do not need to worry about how data is stored or how operations are performed on it.
Acts as a single point of access to the database.
Supports multiple databases.
Offers better maintainability and is migration-proof.
Technologies used:
Java: Classes for entities (POJOs)
C#/.NET: Classes with Entity Framework for ORM.Python: Classes with SQLAlchemy or Django Models.
Database Layer
In software architecture, this layer is responsible for storing, managing, and retrieving data from Database. It interacts only with the Entity Layer/Data Access Layer and cannot communicate directly with other layers.
Why we need this layer?
Centralized Data Management: All data is stored in one place, and operations are performed there.
Data Safety and Security: Ensures that data is stored securely.
Controlled Access: Only the Entity Layer or Data Access Layer can access the data; other layers cannot.
Maintainability and Scalability: Makes it easier to maintain and scale the application.
Technologies used:
Mostly used Database are
Relational Databases:Data is stored in the form of tables, where columns represent the attributes of a resource, and rows represent the data for that resource.
Examples:MySQL, PostgreSQL, and Oracle Database are some popular relational databases.
Non-Relational/NoSQL Databases:Data is not stored in the form of tables.Instead, it uses flexible data models like key-value pairs, documents, column based, or graphs etc
Examples:MongoDB, CouchDB,DynamoDB.
