Enhancing Application Flexibility with Plugins and Onion Architecture

Introduction

In a talk filled with insights and practical advice, we explore the journey of a development team in a large IoT integrator company towards achieving a modular and easily maintainable codebase. This journey is marked by the adoption of plugins and onion architecture, driven by the need to handle a vast array of IoT devices and the challenges of code maintenance and evolution in a dynamic business environment.

The Challenge of Modular Deployments

The team faced a significant challenge: a large portion of the device integrations they developed never reached production, leading to a bloated codebase cluttered with unused code. This situation necessitated a strategic approach to code structure, aiming for ease of maintenance, the ability to quickly implement new device types, and, crucially, the capability to easily remove unused code without disrupting the overall system.

Embracing Onion Architecture

At the core of their strategy was the adoption of onion architecture. This architectural pattern emphasizes placing the domain model at the center of the application, surrounded by layers that depend only on the core, thus preventing external dependencies from leaking into the domain logic. Such a structure promotes clean, testable, and maintainable code, making it easier to evolve the codebase over time.

Key Benefits of Onion Architecture

• Isolated Domain Model: Ensures that the core business logic is shielded from external changes and dependencies.
• Testability: Facilitates easier unit and integration testing, as dependencies can be mocked or stubbed out at the edges.
• Flexibility: Makes it simpler to replace or update external dependencies without impacting the core domain logic.

Implementing Plugins for Modular Functionality

The team's next step was to introduce plugins to handle the specific logic for different types of IoT devices. This approach allowed them to encapsulate device-specific functionality in separate modules that could be easily added or removed from the main application, aligning perfectly with their goal of modular deployments.

Strategies for Plugin Integration

• Dependency Injection (DI): Leveraging DI containers to dynamically register and resolve services at runtime, based on the plugins loaded into the application.
• ASP.NET Core Application Parts: Utilizing application parts in ASP.NET Core to dynamically include controllers and views from plugin assemblies.
• Custom Serialization: Handling polymorphic deserialization to manage device-specific data structures without compromising security.

Lessons Learned and Best Practices

Through this journey, the team learned valuable lessons on structuring code for flexibility and maintainability. Some key takeaways include:

• Prioritize Code Structure: Invest time in structuring your code well from the start. It pays off in the long run by reducing friction and making the codebase more adaptable.
• Consider Plugins for Modularity: Plugins can significantly enhance the modularity of your application, making it easier to add, update, or remove functionality as needed.
• Avoid Overcomplicating Deployment: A well-structured codebase with plugins can reduce the need for complex deployment strategies, such as microservices, until they are truly necessary.

Conclusion

The journey of transforming a cluttered, difficult-to-maintain codebase into a modular, clean, and maintainable system using plugins and onion architecture offers valuable insights for developers and teams facing similar challenges. By focusing on clean code structure and embracing modular deployments, it is possible to build applications that are not only easier to maintain but also more adaptable to changing business needs.

For more detailed insights and technical discussions on implementing these strategies, watch the full talk here.