Component integration creates value by automating the costly and error-prone task of imposing desired behavioral relationships on components manually. Requirements for component integration, however, complicate software design and evolution in several ways: first, they lead to coupling among components; second, the code that implements various integration concerns in a system is often scattered over and tangled with the code implementing the component behaviors. Straightforward software design techniques map integration requirements to scattered and tangled code, compromising modularity in ways that dramatically increase development and maintenance costs.