Chapter 19. Building Systems with Assurance

LORD BARDOLPH: When we mean to build,
We first survey the plot, then draw the model;
And when we see the figure of the house,
Then must we rate the cost of the erection;
Which if we find outweighs ability,
What do we then but draw anew the model
In fewer offices, or at last desist
To build at all?

—King Henry IV, Part II, I, iii, 41–48.

Designing and implementing systems with assurance requires that every step of the process involve an appropriate level of assurance. This chapter discusses how to provide the levels of assurance during the steps of building a system. It emphasizes the documentation and methods required to obtain evidence to support claims of assurance and provides the context for detailed discussions of methodologies such as formal program verification and testing.