Tuesday, August 21, 2012, 2:43:06 PM, you wrote: > Thank you Alan for stepping in!
>>>ATS will only cache full object requests. It never caches range requests. > Is this happening also for large files (video files for example) ? I assume > that the cache will fill up quite quickly with this approach, isn't it? > What is currently the strategy used for deciding which files get cached and > which do not? There is a huge amount of logic about deciding what to cache with quite a lot of tunable parameters. In addition most serious users develop their own plugins to control caching logic (all the clients I have worked for have done so). You could start with looking through the documentation for cache.config and remap.config. There is also the issue of how much attention to pay to the HTTP specifications about what can be cached (ATS lets you tune that, by default it obeys the specs). In practice, because ATS does not by default cache "cgi looking" URLs very few video files will be cached. Certainly nothing from YouTube, for instance, unless you write a customized plugin to do so (you might search the email archives for discussions on that subject*). People who write such plugins also tend to build large caches (10s of TBs, or more) and people who don't end up (in general) not caching video files. * Most (all?) streaming video servers encode a lot of data in the URL so that if you try to cache by URL naively you'll cache the same video multiple times and also get very few to no cache hits for all your effort. Something to keep in mind if you ever try to test your changes. >>>There is a team somewhere working on caching partial objects but I don't > know what they current state is. > We are currently collecting data from you guys (the ATS developers mainly) > about how you envision caching the range requests so we maximize our > chances of getting our enhancements accepted back into the mainline project. You should definitely checkout the range changes I posted recently to the list because that will impact your work. The use of alternates for content objects is a key feature that must be supported.
