Component / Service Model

The term “component model” is somewhat overloaded. It often brings to mind complex IoC containers, layers of dependency injection, and a fair amount of indirection. That’s not what we’re aiming for here. What we want instead is something much simpler: a way to build reusable components that are, above all, easy to compose. Imagine a service whose only responsibility is to execute an operation and return a result. Internally, it might be arbitrarily complex—but from the outside, its interface should remain minimal and predictable. In Rust, we can express this idea using the most basic building block we have: a function. async fn execute(op: Operation) -> Result<OperationResult, Err> { ... } That’s it. This tiny abstraction already gives us everything we need. It takes a single input and produces a single output. There’s no hidden state, no framework magic, and no ceremony. Just a clear contract. And importantly, this kind of interface is trivial to test, easy to reason about, a