Using SSI in XML for RSS

Summary: As it turns out, it’s possible to include HTML files in your XML RSS feed using SSI.

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After much investigation, I found that Hughes satellite Internet has been the source of the many “File does not exist” errors on our web server. And so, I will here detail the signs that this is happening, our best theories on why / how this happens, and what can be done about it. In the following, paths are changed to protect the innocent.

So in our httpd error logs, I’ll see things like the following:

[Thu Aug 05 14:14:45 2010] [error] [client 67.142.130.26] File does not exist: /m/vhost/htdocs/file.swf, referer: http://thomblake.com/

Now, no one should be looking for file.swf in that folder, which corresponds to http://thomblake.com/file.swf - it’s actually in /m/vhost/htdocs/resources/file.swf and should be accessed via
http://thomblake.com/resources/file.swf. Also, this affected a tiny percentage of users; most people were not getting errors. However, the javascript contains code like the following:

var location = path + "/file.swf";

I spent some time poking around before I got the idea of doing a whois on the offending IP addresses. It turns out they were all owned by Hughes, a satellite ISP. I had already guessed at this point that the errors might just be caused by a bad proxy or something, and this was pretty well confirmed here. As far as I can tell, Hughes has an ‘accelerator’ that prefetches content that dynamic pages might want at some point. One of the things this does is scrape the js file (without parsing or executing it) for anything that looks like a path. So it sees "/file.swf" and tries to retrieve the file at http://thomblake.com/file.swf.

At this point I had a few options. The obvious choice was to ignore the problem. One obscure ISP has a buggy piece of software that, as far as I can tell, is not even ruining the UX of my website. However, it might be worth finding a work-around, so I plodded onward. Obviously, there is not a reasonable, consistent work-around for this. Since someone else’s software being buggy is the problem, the solution is not to fix it on my end. However, it is possible to fix this for particular cases.

As it turns out, I was only using path in one place, so I was able to rewrite the script so that the ‘accelerator’ looks for the file where it actually is. In theory, this improves the performance of the site for the end-user (since the accelerator is now working properly) and it clears some of the junk out of the error logs. I fixed similar problems in other scripts and CSS files by changing some relative paths to absolute paths where it didn’t seem totally crazy to do so.

I was going to include for reference here a list of all Hughes IP addresses so it would be easier for folks to find this site if they’re trying to debug this sort of error, but those seem hard to come by. Below the fold is a short list via http://ws.arin.net/whois/. If anyone has a complete list handy, feel free to send it along.

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There are some new features over on the right (well, I hadn’t mentioned them yet anyway). Google Latitude shows my current position at most times, and there’s a Google Calendar gadget to tell you what I’m doing. Please let me know if they’re not working.

This post attempts to summarize some things about social media for the uninitiated. I will talk about social media in general, and focus on the different ways people use Twitter.

Of course, other people have already done most of the footwork. Please check out this post by Fred Cavazza, paying particular attention to the image of his taxonomy. Also note this essay by Paul Graham, which highlights the role of social media in the lives of those who use it.

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I haven’t posted anything in a while. Part of this is, “If you don’t have anything awesome to say, don’t say anything at all”. But also I’ve been very busy. You can follow my day-to-day on Twitter, but here are some general things you might be interested in:

I’m working on a review of Moral Machines for the journal Minds and Machines. Wallach and Allen have a book-related blog. My deadline is like, today or something.

I had the chance to talk to Scaz about my research. It was awesome. I can’t post a transcript here due to my university’s ridiculous views on privacy and human research ethics, but I’ll probably talk about it soon.

I will be giving a guest lecture for the SCSU Philosophy Dept this coming Tuesday (March 10) at 3:15 PM. The topic is going to be robots, more specifically the inevitability of a robot uprising. Hope to see you there.

The folks who do Overcoming Bias have a new site called Less Wrong, which is reddit-てき. You should go there if only to check out the site design. It’s pretty neat. I post as thomblake.

EDIT: fixed date for SCSU talk

congypsy.com until recently had a single validation error (XHTML 1.0 strict), and I can’t stand for that sort of thing on a site I work on. The source was the “Latest updates on Twitter” section; I was using Twitter’s pregenerated code bits with just a little modification, and their script expects the <ul> it uses to have a particular ID. The problem came in when I had two of them on a page; obviously, you can’t have two objects with the same ID on one page! But to my surprise, everything worked as expected in Firefox, so I left it alone for a while. (Fail)

So then I realized I could just download the script from the Twitter site, modify it slightly, and free myself from the horror of invalid XHTML. UnFail.

I don’t tend to like short posts here, but I must announce A List Apart’s annual survey for web professional type folks:

This post is a test of some structural stuff.

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I just spent a weekend in Cape Cod, and had some time to think while I was relatively unplugged. Since coming back, I’ve seen a lot of comments out there claiming that people are making too big a deal out of NetFlix removing profiles. I disagree - NetFlix has repeatedly shown themselves to be a bad company, and boycott may be the only rational response. At the very least, after observing the complete lack of professional ethics in those at NetFlix, I regret having given them my personal and financial information. And so I decided that here I should outline a little more thoroughly what’s wrong with what NetFlix has done.

UPDATE: NetFlix is now not getting rid of profiles. But they’re still evil.

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Netflix just informed me that it will no longer have account profiles. Profiles are a useful feature that let multiple people on one account have different queues. We also use them to separate “movie” and “series” queues, so that if we send back a disc of Lost, we get a new disc of Lost.

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