An insight into license tools for open source software systems

• We provide a licensing comparative overview of existing assistive approaches/tools.
• License identification tools present a more mature current state.
• License compliance requires the collaboration of various techniques.
• License graphs are useful in detecting license conflicts.

Free/Libre/Open Source Software (FLOSS) has gained a lot of attention lately allowing organizations to incorporate third party source code into their implementations. When open source software libraries are used, software resources may be linked directly or indirectly with multiple open source licenses giving rise to potential license incompatibilities. Adequate support in license use is vital in order to avoid such violations and address how diverse licenses should be handled. In the current work we investigate software licensing giving a critical and comparative overview of existing assistive approaches and tools. These approaches are centered on three main categories: license information identification from source code and binaries, software metadata stored in code repositories, and license modeling and associated reasoning actions. We also give a formalization of the license compatibility problem and demonstrate the role of existing approaches in license use decisions.