Don't change URIs

I like to keep track of what’s going on in Sacramento tech business by watching various job feeds from Craigslist. Today, I started seeing people selling crap in the Web design job listings feed. Easter baskets, automatic knitting machines, looms, and other related stuff. Upon a little investigation, I discovered that the /art/ url that used to point to Web and Design jobs now points to Arts and Crafts for Sale and the Web/Info Design category is now found at the much more sensible /web/ url.

It certainly seems like a good idea, making the URLS more opaque*. I’ve certainly always wondered why web jobs were found under /art/. But the problem is, now anyone subscribed to that feed, linking to those pages, or building [interesting mashups] with Craigslist data is suddenly getting Arts and Crafts listings instead.

Perhaps Craigslist doesn’t care. They’ve got a good size user base and this change isn’t going to affect that. But use this as an example of what not to do. As Tim Berners-Lee says in Cool URIs Don’t Change,

When you change a URI on your server, you can never completely tell who will have links to the old URI. They might have made links from regular web pages. They might have bookmarked your page. They might have scrawled the URI in the margin of a letter to a friend.

When someone follows a link and it breaks, they generally lose confidence in the owner of the server. They also are frustrated - emotionally and practically from accomplishing their goal.

* or maybe not