I’m working on the server architecture for a new web portal. It’s going to be Amazon-EC2based and will have a nginx front end to several tomcat back end servers. The nginx servers will proxy-cache some dynamic pages (search results, internal web-services queries) and will also have a static page cache based on memcached.

While starting to roll memcached into the solution I noticed that I stoped receiving HTTP 304 responses, everything served off memcached where 200. After digging a little bit on Google I found out it was the expected behavior as memcached doesn’t store the timestamp (last-modified) of the files. So I’ve given it a try and developed a quick patch. You can find it here.

I’m quite puzzled at the simplicity of the patch, as I didn’t need to code the logic to check if the cached page is more recent than the client’s one and return 302 or 200. After successfully returning the last-modified header from memcached, nginx seems to do the rest of the job somewhere on its own!

I have tested the patch today at work and everything seems to work OK. Will do more extensive testings tomorrow and update the path if needed. In the meantime, if someone gives it a try and works for them (or doesn’t), I’m waiting for your feedback.