SIMPL (Synchronous Interprocess Messaging Project for Linux) is discussed at many different levels. At its most fundamental, SIMPL is a set of library functions which allow the passing of encapsulated messages between cooperating processes. On another level, SIMPL is an active open source project which began over a decade ago. Over the years this project has accumulated an extensive body of sample code and extensions. SIMPL is also a great way to design software applications where complexity is encapsulated in separate, easily testable, readily extendable modules. The current state of...