Is it continuations you don't understand or their use in web apps? If the latter then you can see them in use on this site when you click "reply". You get a U

Is it continuations you don't understand or their use in web apps? If the latter then you can see them in use on this site when you click "reply". You get a URL ending /x?fnid=bU389jXsk2. That's a FuNction ID that allows the continuation to be eXecuted and run a bit further. The site used to use them far more but because only the last N continuations were kept, at times of high load users would find the links on the page they were viewing broke on trying to use them; the fnid they referred to had disappeared because N more had been created since. One solution is to increase N. However, any trivial means of generating another M fnids means it's easy for a single attacker to cause N more to be generated. As troels says, RESTful is the way to go. Continuation in my view are flawed for web apps. AIUI pg got away with it for Yahoo Store because they were only used in the shop design side of things where each shop owner could be given his own N storage of fnids, isolated from others. It's been discussed before on here, in particular a post by me around end of April/start of May 2007 that caused pg to email me privately about thinking up new "ddos attacks". A while after that, most of the usage of fnids were replaced by conventional-style URLs so also some remain, M is smaller than it used to be.