The Message Arrived. Did the Operation Succeed?

Prelude Every few years, I revisit one of my favorite papers END-TO-END ARGUMENTS IN SYSTEM DESIGN and this time I decided I will write an exposition of it to maybe inspire others to read it but also serve as a set of notes for my future self. Introduction Imagine we have an application that holds bank accounts for Alice and Bob. Alice wants to transfer $50 from her account to Bob&rsquo;s.