California Site Definition - Your Last Resort

"You can check out any time you like...

...but you can never leave."

(Apologies to the Eagles.)

Joel Oleson, ex of Microsoft, and now an independent consultant and speaker, has just published a new article called "Just SAY NO to Creating Custom Site Definitions". In this article, he provides several excellent arguments for not using Site Definitions. This is fully consistent with the article I wrote a few weeks ago - "First Do No Harm - The SharePoint Customization Hippocratic Oath."

In that oath, the last point was "The Definition of Success: If you must use a Site Definition, understand the ramifications." I expanded it as follows:

None of this is to say that Site Definitions are obsolete, or should never be used. You just need to be aware that this is a very fundamental construct. Once you build a site from a site definition, you cannot change it to a different definition later. You can still tweak it with additional features, but you can't change the "kind" of site it is. It will not be a "SharePoint Team Site", easily and transparently upgradable. It will be an "Acme Group Site", or whatever you have called it, and you need to plan for its entire life-cycle (Much like adopting a puppy). There may be extra steps in the upgrade process, for example (though, at this time, we don't know what those steps might be). You may have trouble getting support if the person who created the Site Definition moves on to greener pastures. This may be worth it for your environment, but it is something you need to take into account.

Elsewhere in that article, I also say that a Site Definition should be pretty close to your last resort. While I have always maintained this position, it is good to see others also coming around.

In many respects, for unwary developers, a custom Site Definition resembles another kind of lodging - euphemistically called a "motel". Site definitions may be attractive, but beware - Sites check in, but they don't check out!

Update:

Ian Morrish has also recently commented on the dangers of using Site Definitions indiscriminately.