It is often said (originally by Phil Karlton) that caching is one of the hardest problems in computer science, along with naming things. This may well be an exaggeration, but caching is certainly difficult. It can also be very frustrating to debug if you are not methodical and precise in your approach.
Caching can apply at various different levels from the browser to the server using many diverse technologies. You rarely use just a single cache even if you don't realize it. Multiple caches don't always work well together, and it's vexing if you can't clear one.
We briefly touched upon caching in the previous chapter, and we'll go into much more detail in Chapter 9, Learning Caching and Message Queuing. However, as caching has an impact ...
