In search of `architectural knowledge'

The software architecture community puts more and more emphasis on 'architectural knowledge'. However, there appears to be no commonly accepted definition of what architectural knowledge entails, which makes it a fuzzy concept. In order to obtain a better understanding of how different authors view 'architectural knowledge', we have conducted a systematic review to examine how architectural knowledge is defined and how the different definitions in use are related. From this review it became clear that many authors do not provide a concrete definition of what they think architectural knowledge entails. What is more intriguing, though, is that those who do give a definition seem to agree that architectural knowledge spans from problem domain through decision making to solution; an agreement that is not obvious from the definitions themselves, but which is only brought to light after careful systematic comparison of the different studies.