Last year, I wrote that A URL is forever. Well, like any good hypocrite, I went and changed my URLs yesterday.

I used to have URLs like:

/blog/2007/5/a-url-is-maybe-not-forever

Originally I thought having the date in there would make my site more scalable, so in 100 years (ha!), I wouldn't have a problem of finding a unique URL for my blog posts. Yesterday, I decided I'd rather have shorter URLs and just make myself come up with unique URLs for my blog posts (a matter of taste, really). So now my URLs look something like this:

/blog/a-url-is-maybe-not-forever

So yes, my URLs weren't forever. But I didn't just change them all and break all the old URLs. No, the original URLs all still work. To do this, I added a 301 (permanent) redirect to my .htaccess file, like this:

RewriteEngine on

# need this forever
RewriteCond %{REQUEST_URI} ^/blog/d{4}/d+/.+
RewriteRule ^blog/d{4}/d+/(.*)$ http://www.thefutureoftheweb.com/blog/$1 [L,R=301]

Now, for the life of this site, I have to support both styles of URLs (at least for all blog posts posted before today). That's a sacrifice I'll have make to have shorter URLs. And that's really what's important: once a URL is released into the wild, it should always bring someone to the page it originally referenced, even if the preferred URL for that page changes.

If you have some constantly running Ajax or JavaScript updates on a page, it might be nice to pause these when the browser is minimized or in the background, or when the user switches to another tab. After all, there's no sense in using the user's CPU and network if they aren't even watching what you're doing.

To achieve this, we can use the window.onfocus and window.onblur events like this:

function onBlur() {
	document.body.className = 'blurred';
};
function onFocus(){
	document.body.className = 'focused';
};

if (/*@cc_on!@*/false) { // check for Internet Explorer
	document.onfocusin = onFocus;
	document.onfocusout = onBlur;
} else {
	window.onfocus = onFocus;
	window.onblur = onBlur;
}

These events work in every major browser (Firefox, Internet Explorer 6/7, Safari & Opera).

Unfortunately, there's no way to tell with JavaScript if the browser is visible to the user. For example, they might be chatting on IM in a small window in front of the browser. You'll also find that the page is 'blurred' when you click into the location bar of the browser (except in Safari). You might want to display a message like "PAUSED" (think Super Mario Brothers) so people know why everything has stopped moving.

I've set up a demo page where you can try this out.

[Update October 14, 2008 - Seems the blur event handler would fire in Internet Explorer when the focus went from the body to an input or link. I've changed them to use document.onfocusin and document.onfocusout instead, which seems to work better. Now, putting focus from the body into an input causes them both to be fired, but one right after the other (onfocusout, onfocusin) resulting in a final "focused" state.]

It's now been six months since I announced I had switched from PHP to Ruby on Rails. Reader Richard Wayne Garganta wrote me to ask:

So, now that you have worked with rails a while - are you still in love with it? I tried it a while back and found out my biggest problem was deployment. I have considered returning to it. Your opinion?

Originally, I decided to start using rails because I was getting bored doing server-side development. I asked myself, why was it so much fun to program in JavaScript, but so boring to program in PHP? I figured it might be the programming language itself that was boring me, so I took a stab at learning Ruby on Rails.

Ruby is a really great dynamic language that is fun to work with (though somewhat tricky to get used to). Rails is a great framework, especially when it comes to using ActiveRecord to simplify working with complex data models. I think that Ruby on Rails is a great way to build a complex web site.

Rails also makes it much easier to set up tests (which I was pretty lazy about) and have separate development and live environments. There's a lot of great solutions to common web development problems that makes Rails a lot more fun to work with, especially on big projects.

Eventually I realised that server-side programming in Rails, while a bit easier and more fun, was still server-side programming. Even though I didn't have to worry about writing SQL and building forms, the types of problems and challenges were basically the same as in any server-side language. I realised that even a new language and framework wouldn't change server-side programming altogether. At the end of the day, I still have a lot more fun coding with JavaScript, Ajax, CSS and HTML.

Lately, though, I've been having a lot more fun coding simple templates using PHP. There's something kind of simple and sweet about making a page dynamic by just by putting a few lines of code in a standalone template. MVC is the only way to build a large site or application that is easy to manage, but if you're doing something simple, it's definitely overkill. It's no surprise that the 37signals and Ruby on Rails web sites run on PHP.

So the moral of the story? Use Ruby on Rails for applications, use PHP for simple web sites, and don't use either of them if your passion is client-side development. :)

I'm starting to get really swamped with work, and it's about time I started looking for some great talent to help me out with cool projects like FlickrCash.

Here's what I need you to be:

• You're a self-employed individual (no teams or agencies, please).
• You're freelancing full-time (at least 20 hours per week).
• You are an expert in JavaScript, Ajax, CSS and XHTML.
• You're always doing your best to produce work that is valid, accessible, and uses JavaScript unobtrusively.
• You're at least familiar with jQuery. (You don't have to be an expert because jQuery is easy to learn.)
• You're very experienced programming on the server side, especially with PHP and MySQL. Ruby on Rails experience is helpful too.

If this sounds like you, drop me a line and let me know. Please give some details like where you live, how long you've been freelancing, what kinds of projects you like to work on the most, what your hourly rate is, etc. I'll be in London for the next week but I'll email everyone back as soon as I can. Thanks!

I wrote a jQuery tutorial which was just put live on IBM DeveloperWorks today: Simplify Ajax development with jQuery.

I discuss a lot of the core functionality and philosophy of jQuery, including an introduction to writing plugins. So if you've heard of jQuery but haven't really decided if you want to use it, or if you've started to use it and want to see what it's capable of, I think you might enjoy the article.