"... it is not true. I have implemented web caching ..." As the quote says, it is not the implementing which is hard, it is the invalidating part that is littl

"... it is not true. I have implemented web caching ..." As the quote says, it is not the implementing which is hard, it is the invalidating part that is little bit tricky. If you try to invalidate the cache in a strict manner, you will not enjoy the benefits of the caching much, since it will invalidate most of the time. If you have more relaxed implementation of it, there is a risk of this exact problem happening.