Re: [Radiant] Caching issue
On 04/12/2009 00:47, Myron Marston wrote: The basic problem I ran into is that the Radiant cache isn't designed with regularly changing content (such as page ratings and comments) in mind. Myron, Thanks for this post. I've been trying to grok exactly how Radiant caches stuff and your message has certainly helped. I mentioned in a thread elsewhere[1] that it might be nice if a page and its children could be assigned a discrete max-age. Having read your post, it seems being able to manipulate the other cache control directives[2] would be good too. Radiant is still new to me, though, so all this may be possible still. [1] http://j.mp/8QTqPi [2] http://j.mp/eLeHU Charles ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
The thing that is kind of unintuitive about HTTP caching is the duality of it - both client and server are responsible. This ultimately makes it very scalable, but (anti-?)patterns that we've grown accustomed to become difficult or confusing at best. Without knowing the specifics of how the ratings extension works, I can tell you one way that you can invalidate the cache correctly: POST to the page that needs to be refreshed, and return the proper status code and headers. In this case, both the cache and the client will recognize that the old version is invalid, and since it's a POST request, the cache won't store the result. This has worked very well in the comments extension, for example (see also: http://github.com/seancribbs/radiant-comments/blob/master/lib/comment_page_extensions.rb). Sean Myron Marston wrote: I found a solution to this today. I wanted to update the list in case anyone else has this problem and also to get feedback. I'm sure my solution can be improved. The basic problem I ran into is that the Radiant cache isn't designed with regularly changing content (such as page ratings and comments) in mind. It sets the cache headers in the set_cache_control method: http://github.com/radiant/radiant/blob/b912a4e622fec974f7ae2d5e0acad1ad25fd06f8/app/controllers/site_controller.rb#L31-38 This works great for static content such as radiant pages...if an admin changes the page, the user may still see the old version for up to the 5 minute cache timeout, and that's not really that big of a deal. But it breaks down when the user _immediately_ needs a fresh version of the page. When they rate a page or add a comment (I'm using both the ratings and comments extensions), its a bad user experience if their rating or new comment doesn't show up--it makes it appear as though it didn't work, and many users will re-submit their comment, leading to duplicates. The solution I found is to use the no-cache header, which, contrary to how it sounds, does allow a browser to cache a page, but instructs it to revalidate it with the server every time. (see http://www.mnot.net/cache_docs/#CACHE-CONTROL for more details). Then I use an ETag so a 304 Not Modified response is sent except when the page has changed. Here's the code: http://gist.github.com/d641725a48e0bf0dd5a8 I'm just getting my feet wet with this HTTP caching stuff for the first time, so it's quite likely this is not an optimal solution, but it's working for me. I'd welcome feedback if anyone has any suggestions for improvements. It strikes me that this is really something that the comments and ratings extensions should be handling, but Radiant doesn't provide hooks to make that easy. Is that on the development roadmap? Myron On Mon, Nov 30, 2009 at 9:24 AM, Myron Marston myron.mars...@gmail.comwrote: I'm using (and improving) the ratings extension for use in my radiant 0.8.1 app. It works well except for a weird caching issue that I haven't been able to solve yet. When a user rates a page, the radiant cache is cleared, so that when they are redirected to the page, they get a fresh version of it that includes the new rating average. On safari, this works as expected. On firefox, I continue to get the old version of the page. I have to manually refresh the page to force it to update the rating. I've investigated it a bit, and discovered that the cached entity and meta files are indeed being cleared at the right time. My server logs show that when I rate a page using safari, it redirects to the page, and my server logs show a hit to SiteController#show_page, indicating that a fresh version of the page is being generated. When I do this on firefox, it redirects, but there is not a hit to SiteController#show_page. I just see a cached version of the page. So, it appears to me that the cache is being properly cleared on the server, but Firefox is continuing to display a version of the page that is has cached on the browser. My best guess is that there is some issue with the HTTP cache headers that causes Firefox to continue to display it's cached page. I haven't dealt with HTTP cache headers before, so I'm not really sure how to go about troubleshooting this. Any suggestions? Thanks, Myron ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
Sean, My project is using both the ratings extension and the comments extension, and I had the same problem with the comments extension. I set the config setting that causes comments to be posted to the page's URL (as you recommended) and while it works great in Safari, it doesn't work in Firefox. In Firefox, the user gets an old version of the page without the comment they have just submitted. Maybe there's something else I don't have configured right? Anyhow, for the time being I'm going to stick with my little etag hack. The site doesn't perform as well, but given that I don't expect much traffic, I'll take correct behavior over faster performance. Myron On Fri, Dec 4, 2009 at 5:29 AM, Sean Cribbs seancri...@gmail.com wrote: The thing that is kind of unintuitive about HTTP caching is the duality of it - both client and server are responsible. This ultimately makes it very scalable, but (anti-?)patterns that we've grown accustomed to become difficult or confusing at best. Without knowing the specifics of how the ratings extension works, I can tell you one way that you can invalidate the cache correctly: POST to the page that needs to be refreshed, and return the proper status code and headers. In this case, both the cache and the client will recognize that the old version is invalid, and since it's a POST request, the cache won't store the result. This has worked very well in the comments extension, for example (see also: http://github.com/seancribbs/radiant-comments/blob/master/lib/comment_page_extensions.rb ). Sean Myron Marston wrote: I found a solution to this today. I wanted to update the list in case anyone else has this problem and also to get feedback. I'm sure my solution can be improved. The basic problem I ran into is that the Radiant cache isn't designed with regularly changing content (such as page ratings and comments) in mind. It sets the cache headers in the set_cache_control method: http://github.com/radiant/radiant/blob/b912a4e622fec974f7ae2d5e0acad1ad25fd06f8/app/controllers/site_controller.rb#L31-38 This works great for static content such as radiant pages...if an admin changes the page, the user may still see the old version for up to the 5 minute cache timeout, and that's not really that big of a deal. But it breaks down when the user _immediately_ needs a fresh version of the page. When they rate a page or add a comment (I'm using both the ratings and comments extensions), its a bad user experience if their rating or new comment doesn't show up--it makes it appear as though it didn't work, and many users will re-submit their comment, leading to duplicates. The solution I found is to use the no-cache header, which, contrary to how it sounds, does allow a browser to cache a page, but instructs it to revalidate it with the server every time. (see http://www.mnot.net/cache_docs/#CACHE-CONTROL for more details). Then I use an ETag so a 304 Not Modified response is sent except when the page has changed. Here's the code: http://gist.github.com/d641725a48e0bf0dd5a8 I'm just getting my feet wet with this HTTP caching stuff for the first time, so it's quite likely this is not an optimal solution, but it's working for me. I'd welcome feedback if anyone has any suggestions for improvements. It strikes me that this is really something that the comments and ratings extensions should be handling, but Radiant doesn't provide hooks to make that easy. Is that on the development roadmap? Myron On Mon, Nov 30, 2009 at 9:24 AM, Myron Marston myron.mars...@gmail.com wrote: I'm using (and improving) the ratings extension for use in my radiant 0.8.1 app. It works well except for a weird caching issue that I haven't been able to solve yet. When a user rates a page, the radiant cache is cleared, so that when they are redirected to the page, they get a fresh version of it that includes the new rating average. On safari, this works as expected. On firefox, I continue to get the old version of the page. I have to manually refresh the page to force it to update the rating. I've investigated it a bit, and discovered that the cached entity and meta files are indeed being cleared at the right time. My server logs show that when I rate a page using safari, it redirects to the page, and my server logs show a hit to SiteController#show_page, indicating that a fresh version of the page is being generated. When I do this on firefox, it redirects, but there is not a hit to SiteController#show_page. I just see a cached version of the page. So, it appears to me that the cache is being properly cleared on the server, but Firefox is continuing to display a version of the page that is has cached on the browser. My best guess is that there is some issue with the HTTP cache headers that causes Firefox to continue to display it's
Re: [Radiant] Caching issue
I found a solution to this today. I wanted to update the list in case anyone else has this problem and also to get feedback. I'm sure my solution can be improved. The basic problem I ran into is that the Radiant cache isn't designed with regularly changing content (such as page ratings and comments) in mind. It sets the cache headers in the set_cache_control method: http://github.com/radiant/radiant/blob/b912a4e622fec974f7ae2d5e0acad1ad25fd06f8/app/controllers/site_controller.rb#L31-38 This works great for static content such as radiant pages...if an admin changes the page, the user may still see the old version for up to the 5 minute cache timeout, and that's not really that big of a deal. But it breaks down when the user _immediately_ needs a fresh version of the page. When they rate a page or add a comment (I'm using both the ratings and comments extensions), its a bad user experience if their rating or new comment doesn't show up--it makes it appear as though it didn't work, and many users will re-submit their comment, leading to duplicates. The solution I found is to use the no-cache header, which, contrary to how it sounds, does allow a browser to cache a page, but instructs it to revalidate it with the server every time. (see http://www.mnot.net/cache_docs/#CACHE-CONTROL for more details). Then I use an ETag so a 304 Not Modified response is sent except when the page has changed. Here's the code: http://gist.github.com/d641725a48e0bf0dd5a8 I'm just getting my feet wet with this HTTP caching stuff for the first time, so it's quite likely this is not an optimal solution, but it's working for me. I'd welcome feedback if anyone has any suggestions for improvements. It strikes me that this is really something that the comments and ratings extensions should be handling, but Radiant doesn't provide hooks to make that easy. Is that on the development roadmap? Myron On Mon, Nov 30, 2009 at 9:24 AM, Myron Marston myron.mars...@gmail.comwrote: I'm using (and improving) the ratings extension for use in my radiant 0.8.1 app. It works well except for a weird caching issue that I haven't been able to solve yet. When a user rates a page, the radiant cache is cleared, so that when they are redirected to the page, they get a fresh version of it that includes the new rating average. On safari, this works as expected. On firefox, I continue to get the old version of the page. I have to manually refresh the page to force it to update the rating. I've investigated it a bit, and discovered that the cached entity and meta files are indeed being cleared at the right time. My server logs show that when I rate a page using safari, it redirects to the page, and my server logs show a hit to SiteController#show_page, indicating that a fresh version of the page is being generated. When I do this on firefox, it redirects, but there is not a hit to SiteController#show_page. I just see a cached version of the page. So, it appears to me that the cache is being properly cleared on the server, but Firefox is continuing to display a version of the page that is has cached on the browser. My best guess is that there is some issue with the HTTP cache headers that causes Firefox to continue to display it's cached page. I haven't dealt with HTTP cache headers before, so I'm not really sure how to go about troubleshooting this. Any suggestions? Thanks, Myron ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
[Radiant] Caching issue
I'm using (and improving) the ratings extension for use in my radiant 0.8.1 app. It works well except for a weird caching issue that I haven't been able to solve yet. When a user rates a page, the radiant cache is cleared, so that when they are redirected to the page, they get a fresh version of it that includes the new rating average. On safari, this works as expected. On firefox, I continue to get the old version of the page. I have to manually refresh the page to force it to update the rating. I've investigated it a bit, and discovered that the cached entity and meta files are indeed being cleared at the right time. My server logs show that when I rate a page using safari, it redirects to the page, and my server logs show a hit to SiteController#show_page, indicating that a fresh version of the page is being generated. When I do this on firefox, it redirects, but there is not a hit to SiteController#show_page. I just see a cached version of the page. So, it appears to me that the cache is being properly cleared on the server, but Firefox is continuing to display a version of the page that is has cached on the browser. My best guess is that there is some issue with the HTTP cache headers that causes Firefox to continue to display it's cached page. I haven't dealt with HTTP cache headers before, so I'm not really sure how to go about troubleshooting this. Any suggestions? Thanks, Myron ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
Myron Marston said the following on 11/30/2009 12:24 PM: So, it appears to me that the cache is being properly cleared on the server, but Firefox is continuing to display a version of the page that is has cached on the browser. My best guess is that there is some issue with the HTTP cache headers that causes Firefox to continue to display it's cached page. I haven't dealt with HTTP cache headers before, so I'm not really sure how to go about troubleshooting this. Any suggestions? Perhaps this ties in with my Last-Modified header question. Though in this case, I should think you have a simple case of changing the header that has nothing to do with the time the page or its children was edited. However I'd be interested in hearing how you change it when the page itself isn't edited. -- Insanity is hereditary. You get it from your kids. ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
On Nov 30, 2009, at 10:24 AM, Myron Marston wrote: I haven't dealt with HTTP cache headers before, so I'm not really sure how to go about troubleshooting this. Any suggestions? Myron, There are several extensions for Firefox that will let you view cache headers. Web Developer and Firebug both come to mind. For Firebug, clear your cache, enable Firebug, click the Net tab in the Firebug panel and load the offending page in Firefox. You should see an entry in the Net panel with a Headers tab. --cro ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
Perhaps this ties in with my Last-Modified header question. Anton--I looked through the archives and couldn't find this question. I'd be curious to read that thread if you can point me in the right direction. There are several extensions for Firefox that will let you view cache headers. Web Developer and Firebug both come to mind. For Firebug, clear your cache, enable Firebug, click the Net tab in the Firebug panel and load the offending page in Firefox. You should see an entry in the Net panel with a Headers tab. Thanks for the suggestion. I should have a been a bit more specific though...I know how to view the cache headers in safari and firefox, but I'm still trying to wrap my head around how these headers work (I just read up on them today for the first time), and I'm not sure what to try next. One difference I'm seeing in the headers is that firefox sends a HTTP_IF_NONE_MATCH header in its request but safari does not. Myron ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
Re: [Radiant] Caching issue
Myron Marston said the following on 11/30/2009 06:26 PM: Perhaps this ties in with my Last-Modified header question. Anton--I looked through the archives and couldn't find this question. I'd be curious to read that thread if you can point me in the right direction. Resent. I looked at the W3 pages that described such things and their use, and there are an awful lot of headers to play with ;-) Do all browsers implement all of them? I'm sure one or other of them could get the 'renew' effect you want, if and only if the browser pays attention to it!! There are several extensions for Firefox that will let you view cache headers. Web Developer and Firebug both come to mind. For Firebug, clear your cache, enable Firebug, click the Net tab in the Firebug panel and load the offending page in Firefox. You should see an entry in the Net panel with a Headers tab. Thanks for the suggestion. I should have a been a bit more specific though...I know how to view the cache headers in safari and firefox, but I'm still trying to wrap my head around how these headers work (I just read up on them today for the first time), and I'm not sure what to try next. You and me,'Bro, you and me! That W3 stuff and all those headers is heady stuff :-) -- helicopter (n): 30,000 parts in tight orbit around a hydraulic fluid leak, waiting for metal fatigue to set in. ___ Radiant mailing list Post: Radiant@radiantcms.org Search: http://radiantcms.org/mailing-list/search/ Site: http://lists.radiantcms.org/mailman/listinfo/radiant
