During the last five years, our research group has studied the architecture and evolution of several large open source systems — including Linux, GCC, VIM, Mozilla, and Apache — and we have found that open source software systems often exhibit interesting differences when compared to similar commercially-developed systems. Our investigations of these systems have involved the creation of software architecture models, software architecture repair, the creation of a reference architecture for web servers, the study of evolution and growth of open source systems, and the modelling of architectural properties of systems that are apparent only at build time.
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