Greetings, everyone! If you’ve ever worked on Java applications, you’ve probably heard terms like “Layered Architecture” or “MVC” (Model-View-Controller) thrown around. But what are Layered Architecture and MVC exactly? And how do they help with building robust, scalable applications? In this post, we’ll dive into the complexities of layered architecture designs in Java and explore how they can benefit you, and your next project!
What is Layered Architecture?
Layered architecture, also known as N-tier architecture, divides an application into separate layers, each with a different responsibility. This separation of concerns (SOC) makes it scalable, easy to maintain and way more organized.
Why Java?
Java’s versatility and object-oriented nature make it an excellent choice for implementing layered architectures. Its well developed ecosystem, with frameworks like Spring Boot, further simplifies implementing N-tier architectures.
3-Tier Architecture
For this example, we will be focusing on a 3-tier architecture. This model is one of the most commonly used but is by no means the only option. Other configurations may involve 4 or more tiers, each with its specialized functionality, such as caching or message queues. There will be more info on this later on.
The Layers Explained
- Presentation Layer
This layer is the user interface of your application, often created with servlets and .jsp pages in Java applications. In Spring Boot, you might use Thymeleaf or even handle RESTful API calls in this layer.
Key Concepts:
User Authentication*: Decides who can access what.
User Input Validation: Cleans and validates user input before it reaches the business layer.
2. Business Logic Layer
The Business Logic Layer is like the gears in a clock, each turning and interacting with precision to keep the entire system operating smoothly.
Key Concepts
Domain Logic: refers to the core business rules, processes, and operations that are specific to a particular domain or industry. It encapsulates the essential functionality and behaviors that define how a business or application operates within its domain.
Data Transformation: Converting data into a useful format for the Presentation or Data Access Layer.
3. Data Access Layer
This layer serves as the gateway to your data store. In Java, this often involves using JPA (Java Persistence API) or Hibernate for ORM (Object-Relational Mapping). I.e. you can use databases, from SQL-based like MySQL to a NoSQL database like a MongoDB
Key Concepts
Data Retrieval: Queries to fetch data from your database.
Data Manipulation: CRUD operations (Create, Read, Update, Delete).
Beyond 3-Tiers
It’s worth mentioning that not all architectures are limited to three layers.
In a 4-tier architecture, an additional “Delivery Layer” is often included:
- Delivery Layer: Responsible for delivering the application logic to various client types. It allows the core application to serve different platforms like web, mobile, or even IoT devices, without altering the business logic.
More complex systems may require additional layers for various functionalities:
Cache Layer: For faster data retrieval.
Message Queue Layer: For asynchronous processing.
These extra layers allow for even greater separation of concerns and can be crucial in highly scalable or distributed systems.
Conclusion
Layered architecture can offer an advantage in developing Java applications. It provides a clean separation of concerns, which is not only good for code maintainability but also vital for team collaborations. The next time you’re tasked with building a Java application, consider making use of a layered architecture for a more organized and maintainable codebase.
* Authentication vs. Authorization: A Brief Clarification
While discussing the Presentation Layer, you may have noticed an asterisk next to ‘User Authentication’. This is because authentication and authorization, though closely related, serve different purposes:
Authentication: This confirms the identity of the user trying to gain access. Essentially, it asks the question, “Are you who you say you are?”
Authorization: Once authenticated, authorization determines the level of access the user has within the application, answering the question, “What are you allowed to do?”
Understanding the subtle difference between these terms is key to implementing a secure and functional application.
About the Author
I’m a full-stack developer and a curiosity driven, tech enthusiast based in Athens, Greece. Currently attending Coding Factory bootcamp from AUEB, and in my spare time I code and experiment with anything I can get my hands on tech-wise.