On Thu, Aug 13, 2009 at 8:10 AM, Amos Jeffries<squid3@xxxxxxxxxxxxx> wrote: > Terry wrote: >> >> Hello, >> >> I don't have squid implemented yet. >> >> I am researching a web architecture issue I am seeing with a site. >> Squid may be a bandaid for what I think may be some poor development >> architecture decisions. There are concerns that the site is written >> in a way that browsers and reverse proxies cannot cache it >> appropriately. And these aren't my concerns by the way. We also have >> A10 load balancers in house that do some caching. They said they >> can't cache this content. I don't want to go into their reasoning >> because I don't believe it. >> >> Here's an example of an image as seen from the client. I pulled this >> right out of my firefox memory cache: >> http://foo.domain.com/Image.aspx?i=db1edbcd-2375-4bae-b33f-a53ced60deed >> >> 1. If it's in the memory cache, can I assume that browsers and proxies >> can cache it? Also, I never saw these objects in my disk cache. Not >> sure if that's significant or not. > > No. The browser has additional information such as who is logged in and > whether your session with the website is the same. They are also allowed to > cache objects personal to you. > > Proxies and caches only have the URL and some other limited data to base the > checking on. If there is any chance it was a private object it will not be > cached naturally. > >> >> 2. Does firefox still interpret this as an image and cache it as one >> or is this considered dynamic content that may be problematic? > > Not enough information to even guess. What headers are present? Does the > website require login? does the same image ever change URL (including the > query string) and why/when/how often? are alternative image formats > available at the exact same URL? > > Any one of those answers may make the object non-cacheable by shared > proxies. > >> >> I think that's enough information to start a conversation. Thanks for >> any insight! > > foo.domain.com does not resolve here so I can't verify the object. > Please pick some of the URLs and enter them into http://www.redbot.org for > review of cacheability. > > Amos > -- > Please be using > Current Stable Squid 2.7.STABLE6 or 3.0.STABLE18 > Current Beta Squid 3.1.0.13 > Thank you both for replying. I haven't messed with squid and caching for 5+ years and its all slightly coming back to me. The identifier in the URL is not unique based upon the session of the user. https://foo.domain.com/Image.aspx?i=db1edbcd-2375-4bae-b33f-a53ced60deed the i=db1edbcd-2375-4bae-b33f-a53ced60deed is a unique identifier for the image and its size. Based on that, it should be cacheable but the developers are setting it to nocache for some reason. I am guessing they reused some code for other dynamic content and failed to see this aspect.
