License integration patterns: Addressing license mismatches in component-based development

In this paper we address the problem of combining software components with different and possibly incompatible legal licenses to create a software application that does not violate any of these licenses while potentially having its own. We call this problem the license mismatch problem. The rapid growth and availability of Open Source Software (OSS) components with varying licenses, and the existence of more than 70 OSS licenses increases the complexity of this problem. Based on a study of 124 OSS software packages, we developed a model which describes the interconnection of components in these packages from a legal point of view. We used our model to document integration patterns that are commonly used to solve the license mismatch problem in practice when creating both proprietary and OSS applications. Software engineers with little legal expertise could use these documented patterns to understand and address the legal issues involved in reusing components with different and possibly conflicting licenses.