Mining the specialization interface of a framework is a difficult task in the presence of poor documentation. This paper develops a systematic goal-oriented approach to find, specify, and use the specialization interface of a framework as a set of patterns.

The presented approach is goal oriented--it is based on an analysis of the expected behavior of the framework user. The benefit is to have a direct link between the interface specialization and the assumed goals of the product developer.

This paper is well written and easy to follow, however two aspects remain rather weak. First, it is not clear how much more expressive specialization patterns are when compared to a description in a metamodel, for example a unified modeling language (UML). The second point, which is a consequence of the first, is that the case studies would be more convincing if they had been described more accurately.

The authors keep the description informal, making it easy to follow and understand. But a deeper motivation and validation would make this paper stronger.