Delivering Dependable Reusable Components by Expressing and Enforcing Design Decisions

A component is usually complemented with guidelines expressing its proper use, e.g. the appropriate order of calls that clients should conform to. During reuse, clients could easily alter such an order, and this could result in reused components that become unreliable, since architectural guidelines have not been honoured. Sometimes architectural guidelines are simply unknown, hence whether components are misused by clients is uncertain. This paper proposes an approach to document the architectural guidelines that client classes should comply with when reusing a component. We empower component developers to provide such guidelines, conveying design decisions, along with the code of components in such a way to be apt to automatic checks. Then, clients compliance with architectural guidelines of reused components can be automatically checked by an aspect-based tool. As a result, proper usage of reused components can be ensured, and in turn the behaviour of components should be correct. This strengthen the reliability of the resulting system. Especially for continuous evolution, having automatic conformance checks is paramount for obtaining the correct behaviour of reused components.