What makes a cool URI?
A cool URI is one which does not change.
What sorts of URI change?
URIs don't change: people change them.
There are no reasons at all in theory for people to change URIs (or stop maintaining documents), but millions of reasons in practice.
In theory, the domain name space owner owns the domain name space and therefore all URIs in it. Except insolvency, nothing prevents the domain name owner from keeping the name. And in theory the URI space under your domain name is totally under your control, so you can make it as stable as you like. Pretty much the only good reason for a document to disappear from the Web is that the company which owned the domain name went out of business or can no longer afford to keep the server running. Then why are there so many dangling links in the world? Part of it is just lack of forethought. Here are some reasons you hear out there:
We just reorganized our website to make it better.
Do you really feel that the old URIs cannot be kept running? If so, you chose them very badly. Think of your new ones so that you will be able to keep then running after the next redesign. //]
Why should I care?
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.
Enough people complain all the time about dangling links that I hope the damage is obvious. I hope it also obvious that the reputation damage is to the maintainer of the server whose document vanished.
So what should I do? Designing URIs
It is the the duty of a Webmaster to allocate URIs which you will be able to stand by in 2 years, in 20 years, in 200 years. This needs thought, and organization, and commitment.
URIs change when there is some information in them which changes. It is critical how you design them. (What, design a URI? I have to design URIs? Yes, you have to think about it.). Designing mostly means leaving information out.
The creation date of the document - the date the URI is issued - is one thing which will not change. It is very useful for separating requests which use a new system from those which use an old system. That is one thing with which it is good to start a URI. If a document is in any way dated, even though it will be of interest for generations, then the date is a good starter.
