This paper presents a model for understanding behaviour of agents using and/or contributing to open source software. The model illustrates behaviour of agents under three licenses regimes: 1) The GPL, The BSD and 3) The Microsoft EULA. The latter license is not an open source license and is included as both a reference and as an example of a general situation where users do not contribute source code. The model is uses economic theory of externalities and opportunity cost as a measure of agents' costs. The basic premise is that agents will only participate in development if there is a net benefit. Agents are divided into firms and individuals, which can be either maintainer or user-developers. A maintainer is an agent responsible for releasing new versions of a program and a user-developer is an agent who use but may also become a developer. It is observed through the model that the three licenses induce different incentives and dynamics for maintainer and user-developer and the paper explains, from an economic standpoint, the mechanisms that ensure programs are developed and maintained under the three license regimes.
Telematics and Informatics, 2005, Vol 22, p. 111-133