Month: December 2005

AJAX vs. AHAH

A few weeks ago a few folks discovered the section of the , which discusses “how to optimally use Microformats as the encoding for REST web services”, but has grown to include broader discussions of applying to both protocols and javascript techniques.

One of those principles could be rephrased as: Why use XML when (X)HTML will do?

Perhaps another could be rephrased: Why bother with parsing/transforming when you can just get the data in a presentable format? After all, we all know that is better.

(Asychronous HTML and HTTP) is the result of applying both of those principles to the incredibly buzzworthy . Strictly speaking, AHAH is simply a subset of AJAX, albeit a subset that openly de-emphasizes the in AJAX.

AJAX Magazine provided a good overview of the advantages of AHAH over “traditional” XML-based AJAX.

Keith Devens summarized it well:

…instead of grabbing arbitrary XML and processing it on the client-side with Javascript or XSLT and inserting things into the DOM, you just grab bits of (X)HTML from the server and inject them directly into your page. So, the client side does much less logic and merely needs to say “replace the content in the element with this ID with the (X)HTML at this URI

So if you’ve been wondering what this AJAX stuff is about, take a look at AHAH, you might find it gets you 90% of the hyped user interface advantages with only about 10% of the hype (and effort for that matter). That’s the kind of 90/10 rule we like around here.

But don’t take our word for it. See .

Syndicate Microformats

The two day Syndicate Conference finished up yesterday. Lots of good news about and more and better support for microformats was announced both during the conference and the weeks leading up to it. I’m still collecting/collating all the recent announcements.

For now, check out the following:

And that’s just a taste. More to follow.

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Rel vs. Rev

Another note in my very-neglected series on Semantic XHTML basics started awhile back.

It seems that everytime I present microformats, I need to explain the difference bettween the rel and rev attributes. Its understandable that most people don’t grasp the difference, as I’m sure most webdevelopers haven’t needed to make use of these semantics.

We have a good document on the wiki about this, so consider this an introduction.

First of all, rel is an attribute which can be applied to <a> and <link> to define the relationship between the linked document and the current one. So, a very common example is a link to a feed. This blog has:

<link rel="alternate" type="application/rss+xml" href="http://www.microformats.org/feed/" />

This can be read as http://microformats.org/feed/ is an alternate for http://microformats.org/ (Incidentally, the feed could link to this blog with rev="alternate", which would have exactly the same meaning. More on rev in a minute.).

rel is used by XFN, rel-tag, rel-directory and rel-payment microformats.

Now, rev is just like rel, but the relationship is reversed (I think of rev as “reverse relationship”). It gets used in the vote-links microformat like this:

<a href="http://supr.c.ilio.us/blog/" rev="vote-for" title="supr snark">supr.c.ilio.us rocks!</a>

…which would be read as “this document is a vote-for http://supr.c.ilio.us/blog/”.

rel and rev are useful for describing the relationships between two resources on the web. Remember, it is only the relationship between the documents, not the documents themselves which are described. Describing the documents themselves is another topic altogether.

Again, see the wiki for more info.

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