How can I understand a heavily decoupled C# system wired together with dependency injection?
Asked by
MellowQuartz42
I'm working with a C# codebase built around roughly 50 generic pipelines implementing Pipeline. Events are handled through many generic publishers and subscribers that implement interfaces such as Handler and Plug. Most of the wiring happens automatically through Autofac, including assembly scanning and dependency injection.
The design is difficult to trace with normal IDE tools. Finding references often leads nowhere because concrete classes may never be instantiated or referenced directly. Instead, an abstract base type is registered with the container as the implementation of a generic interface, and that interface—or another inherited interface—is what the application actually uses.
It took me several hours just to work out how the pipelines were connected, and I'm still not completely sure I understand the runtime flow. Static analysis feels especially unreliable in this setup. What techniques do you use to explore and reason about code that relies heavily on generic interfaces, assembly scanning, and dependency injection? I'm looking for practical approaches that don't require paid AI tools.
Answers
Start with the Autofac registration code rather than searching for references to each concrete class. Look for assembly scanning or bulk registration calls that register implementations of Pipeline, Handler, or similar interfaces. That will tell you which assemblies are involved and which concrete types are available to the container.
For the runtime path, put a breakpoint in the generic interface method or in the common base class, then trigger a real event. The call stack will show the concrete implementation Autofac selected and how the event moved through the system. This is often much faster than trying to infer everything from static references.
Reply to this answer
It’s worth remembering that the difficulty you’re having is a real cost of this design, not simply a failure to understand it. Dependency injection and open generics reduce coupling, but they also hide construction and call relationships from static tools. Keep a small map of registrations, resolved concrete types, and event flow as you investigate. If the codebase has maintainers, ask whether there is an established registration convention or a diagnostic mode; teams sometimes have tools for dumping the container configuration.
Reply to this answer
A sequence diagram or a simple hand-drawn flowchart can help a lot. Pick one event and document where it originates, which publisher emits it, which handlers receive it, and which pipeline processes it. You don’t need to diagram all 50 pipelines at once—trace one complete path, then use it as a template for the others.
This architecture can be useful when components need to be loaded or replaced independently, such as plugin or regulated algorithm systems. The tradeoff is that the wiring is moved from ordinary code references into configuration and container registration, so the runtime behavior is harder to discover.
Reply to this answer
I usually begin by learning the small part of the DI library that the application actually uses, then find the project’s registration conventions. Wiring may be centralized in one module or distributed across feature-specific setup files.
After that, I run the application under a debugger and inspect the resolved services. Some codebases also have registration diagnostics or a startup dump that lists the container contents. Combining that information with breakpoints gives you a concrete map instead of relying only on IDE navigation.
Reply to this answer
Add your answer
Answers are reviewed before publication.
Related Discussions