Vertical Slice Architecture: Breaking Down Slices for Effective Software Development
So, what exactly is vertical slice architecture and how does it improve software development? Let's dive deeper into this topic and explore its benefits.
Vertical slice architecture, as the term suggests, involves slicing the application vertically, across all layers, to create fully functional features. Traditionally, developers used to work in a layered architecture where each layer, such as the presentation layer, business logic layer, and data access layer, was developed in isolation. While this approach had its advantages, it often led to delays in feature delivery and increased complexity when integrating different layers.
The Challenges of Layered Architectures
Layered architectures are a common approach to organizing software systems, where each layer or tier represents a separate project within the overall solution. Examples of layered architectures include N-tier architecture and Clean architecture.
The main goal of layered architectures is to separate the concerns of different components, making it easier to understand and maintain the software system. This structured design approach brings various benefits, such as improved maintainability, flexibility, and loose coupling.
However, it's important to recognize that layered architectures also impose constraints and rigid rules on the system. The direction of dependencies between layers is predetermined and needs to be carefully followed.
For instance, in Clean Architecture, there are specific dependency rules:
1. The Domain layer should have no dependencies.2. The Application layer can reference the Domain layer.
3. The Infrastructure layer can reference both the Application and Domain layers.
4. The Presentation layer can also reference both the Application and Domain layers.
As a consequence of these rules, high coupling is often observed within each layer, while low coupling is achieved between layers. This doesn't imply that layered architectures are inherently flawed. However, it does mean that in practice, you may end up with many abstractions between individual layers. This abundance of abstractions can lead to increased complexity, as more components need to be maintained.
What is the concept of Vertical Slice Architecture?
Vertical Slice Architecture emerged as a solution to the challenges posed by layered architectures, where implementing a feature requires modifications across multiple layers. With vertical slice architecture, developers focus on delivering a complete feature by spanning all layers. This means that a single team is responsible for developing the entire vertical slice, ensuring that the feature is fully functional from the user interface down to the data persistence layer. Instead of passing the code between specialized teams, the vertical slice architecture encourages cross-functional teams that can work independently and deliver end-to-end features.
Let's picture the process of adding a new feature in a layered architecture:
1. Updating the domain model.2. Modifying validation logic.
3. Creating a use case using MediatR.
4. Exposing an API endpoint from a controller.
These layers make the system's cohesion weak, as numerous files are created across different layers.
In contrast, Vertical Slice Architecture adopts a distinctive approach:
1. All the files related to a specific use case are grouped together in a single folder.
2. Consequently, the coherence within a given use case becomes remarkably high.
3. This simplifies the development process as all relevant components are conveniently located in close proximity.
One of the key benefits of vertical slice architecture is faster feature delivery. By breaking down silos, developers can work in parallel and reduce dependencies between different layers. This enables them to deliver features more quickly as they don't have to wait for other teams to complete their work. It also allows for better collaboration and communication within the team, fostering a sense of ownership and accountability.
Additionally, vertical slice architecture promotes better testability and maintainability. With traditional layered architectures, testing a specific feature could involve setting up complex integration tests that span multiple layers. However, with vertical slice architecture, each feature is a self-contained unit that can be tested in isolation. This not only simplifies the testing process but also makes it easier to modify or add new features without affecting other parts of the application.
Moreover, vertical slice architecture improves the overall user experience. As each feature is developed end-to-end, it ensures a seamless flow from the user interface to the data layer. This approach allows for quick iteration and gathering user feedback, enabling developers to make necessary adjustments early on in the development cycle. By focusing on complete features rather than individual layers, developers can better understand the needs of the end-users and create a more intuitive and user-friendly application.
How to Implement Vertical Slices
When developing an API, the first step is to break down the system into commands (POST/PUT/DELETE) and queries (GET). This approach aligns with the CQRS pattern, allowing you to benefit from its advantages.
Vertical slices, on the other hand, adopt a narrow focus on a specific feature. This enables you to handle each use case independently and tailor the implementation to meet its unique requirements. For example, one vertical slice may utilize EF Core to implement a GET request, while another vertical slice may rely on Dapper and raw SQL queries.
However, implementing vertical slice architecture requires careful planning and coordination. It's essential to define clear boundaries for each vertical slice, ensuring that they are not too small to become fragmented or too large to hinder development speed. Proper communication and coordination between teams are also crucial to avoid any duplication of effort or conflicts when integrating different vertical slices.
Restructuring with the REPR Pattern for Solution Architecture
When it comes to organizing a solution, layered architectures like Clean Architecture typically group code based on technical concerns. However, there is an alternative approach called the vertical slice architecture, which organizes code around features or use cases.
To structure APIs based on features, the REPR pattern can be applied. REPR stands for Request-EndPoint-Response, which aligns perfectly with the concept of vertical slices. This can be achieved using libraries like MediatR.
In the REPR pattern, web API endpoints are divided into three components:
1. Request
2. EndPoint
3. Response
Here is an example of a solution structure in the .NET framework. The Features folder contains the vertical slices, with each slice representing an API request or use case.
In conclusion, vertical slice architecture is a powerful approach to software development that breaks down silos and improves efficiency. By focusing on fully functional end-to-end features, developers can deliver high-quality products faster, while also improving testability, maintainability, and user experience. While it requires careful planning and coordination, vertical slice architecture is worth considering for any development team aiming to enhance their software delivery process and deliver value to their users more effectively.
Comments
Post a Comment