A reference architecture for Web browsers

A reference architecture for a domain captures the fundamental subsystems common to systems of that domain as well as the relationships between these subsystems. Having a reference architecture available can aid both during maintenance and at design time: it can improve understanding of a given system, it can aid in analyzing tradeoffs between different design options, and it can serve as a template for designing new systems and re-engineering existing ones. In this paper, we examine the history of the Web browser domain and identify several underlying phenomena that have contributed to its evolution. We develop a reference architecture for Web browsers based on two well known open source implementations, and we validate it against two additional implementations. Finally, we discuss our observations about this domain and its evolutionary history; in particular, we note that the significant reuse of open source components among different browsers and the emergence of extensive Web standards have caused the browsers to exhibit "convergent evolution".