A high-level view of all of this feed reader stuff

Yeah, I know, it's another post about feed reader stuff. I figured people are probably wondering what the results have been looking like. I also wanted to see things in aggregate, and fixing my mistakes turned out to really need a "30,000 foot view" approach.

So, here's a screen shot of the top third of my admin tool with the unique keys removed to give a taste of what we've all been collectively finding out.

This is showing the number of requests, how many were conditional or not, which ones presented a good If-Modified-Since value, one that was out of sequence ("oos"), or made up entirely. Then it does the same three counters for If-None-Match values.

Next up are the counters for cookies, referrers and query parameters which were needlessly presented for whatever reason, and finally it's whether the requests are showing up over IPv4 or IPv6.

I mostly rigged it this way so I could watch the "ims bogus" counts drop out as I fixed each set of entries in the database. (What a mess.)

There are more than a few keys which were issued but haven't been used, and that's what those grey rows are in the table. Even with that reduction, it still goes on much too far to present as a single screen shot - there are a *lot* of people taking part in this thing.

So, what can we learn from this view? The first row was just me running tests, so I deliberately tripped a bunch of badness to make it show up in the reports. Then there are a few boring ones which were more tests from me, and then it starts getting into actual programs.

See the one with 256 hits and 256 unconditional requests? That'd be the "leaked to the clown" situation from the other day. They're still showing up over and over to fetch that thing.

How about the one with 1258 bogus IMS values? That'd be a feed reader which is sending the feed update time, not the Last-Modified time. That's a nasty one since it looks conditional, but in practice it is not. Every one of those requests gets the full feed shipped out. (This is a rather popular program, so there are lots of these things hitting the real site all day every day. Groan.)

The really interesting parts of this are the ones which are consistently sending out-of-sequence If-Modified-Since and If-None-Match values. Out of sequence in this context means "they're sending a value, but it's an old one, not the most recent one served to them on their last hit". It seems we have managed to trip a LOT of caching bugs in these programs. They latch in some bad state, and just keep going like this forever. Not good!

One thing that has been gratifying about this is when feed reader authors have changed something in their code and then reached out to me for a fresh key. That lets them start from scratch with their new behavior and leave the old one behind. I'm always happy when this happens.

This also adds a new dimension that I'll have to start tracking, now that we have tests ending and others coming in to replace them: staleness. I'll only be looking at things which are still actively checking in so as not to penalize anyone who's improved their stuff. We will leave the old behaviors behind and focus on what's current.

That's the best you can hope for: a series of improvements.