Best Principles in the Design of Shared Software

Code reuse has long been a holy grail of Information Technology. When realized, it is manifested either by sharing source code or by sharing binary code. The free software and open source movements promote the sharing of source code. The proprietary world promotes market mechanisms through exclusive rights of ownership to binary code, protected by licenses and copy protection mechanisms. When binary code is shared by many owners in the proprietary world, it is packaged as either software libraries or software frameworks, abstractions in which common binary code providing generic functionality can be leveraged, extended, and specialized. With software libraries, owners write code that calls library code; with software frameworks, owners write callback code that is called by framework code. This paper details benefits and drawbacks of these two types of shared binary code abstractions and suggests best practices, from a practical perspective and concerning large and complex implementations of software frameworks in sizable enterprises.