Armstrong Chapter 5

Let's face it. No one can write perfect code. The best we can hope for is to write fault tolerant code and even that is difficult. One of the first things that needs to be understood by the programmer is what exactly is an error. There are also different levels of severity for errors. Some errors can be handled by the function that caused the error, while others may need to know more information in order to fix the problem. In these cases the programmer will just throw an exception and let the supervision trees handle where to take the problem next. Supervision trees are hierarchies of processes where the parent has an OR/AND relationship with its children. If a parent receives an exception from one of its children, depending on its relationship, it may restart one or all of its children processes.