needs Cache-Control headers with max-age

[reedstrm]

In order to effectively cache the results of exercise look ups, it would be good if the server, in addition to providing ETags and supporting If-None-Match (which it does), would provide a cache-control header with a reasonable value, fairly large, since exercises do not change often.

[reedstrm]

current value is 'max-age=0, private, must-revalidate', which I think actually saves 0 time. In my measurements of If-None-Match vs. full fetches of exercises, I get the same total fetch time.

[Dantemss]

Yeah weak ETags like we use would only save the data transmission time which is tiny with a fast internet connection in comparison to the time it takes to generate the JSON.

I created a change request ticket to improve the cache headers and cache the result JSON somewhere: https://trello.com/c/ZNuzEBDK

[nathanstitt]

this is good but I think it'll only help us in the rare case of a web-browser download.

For instance I'm not seeing how the the Tutor importer could supply a meaningful only-if-modified-since header.

[Dantemss]

ETags already work :) Only Cache-Control still needs to be added. I think for published exercises we can set it to 1 year.