It's been a while since I gushed about Yahoo Pipes, hasn't it? Well, the RSS-combining service remains insanely powerful. This morning I decided to try using it with one of my other favorite web technologies: jQuery. When combined, the two can take the place of many aggregation tasks that previously required a server.

Here's the problem I set out to solve: a bunch of my friends write for more than one blog. They usually have a personal site and contribute to a number of other multi-author blogs. Sometimes they keep a list of their posts in a del.icio.us sidebar block. But maintaining that can be kind of a pain — they have to remember to create a new del.icio.us entry every time they post. Clients like Pukka make using del.icio.us a breeze, but this workflow is still not as automated as it could be (in that it exists at all).

As you know, Pipes makes it easy to combine and filter RSS feeds. Here's a pipe I threw together containing feeds from a couple of EchoDitto clients and our main blog. Naturally we love all of our clients equally, but for my friends' purposes a simple Pipes filter block could be applied to check the dc:author field, ensuring that no coauthors' posts are retrieved. The result will be an aggregated feed of the author's entries.

But how to retrieve them? jQuery 1.2 added in support for JSONP, an unbelievably slick technology that allows Javascript to load JSON data from different domains. There are two things you need to know to get this to work with Pipes: how to get the service to spit out JSON, and how to pass it a JSONP callback (which safely assigns the JSON to a given variable name — without this, loading cross-domain data would be a huge security hole). Both things are accomplished by adding parameters to your pipe's querystring.

I'm a little shocked to see that we haven't talked about Yahoo Pipes around these parts. It's an awfully cool service, and one that we use around the office for various non-mission-critical functions — getting larger photos from a Flickr stream for display on the monitors in the lobby, for one thing.

For those unaware, Pipes lets you mix, translate, annotate and otherwise alchemically modify feeds of all sorts. Want to add a (possibly) relevant photo to each entry on your blog? Or only get posts from a particular author on a group blog? Or get filtered Craiglist real estate listings translated into German and sent to your mobile phone? Pipes can do all of this, and does so via a terminally-slick GUI.

But recently a friend tipped me off to Pipes' most significant capability. The folks at Yahoo! have unveiled the Holy Grail of feed-manipulation components: a JSON-powered interface to external web services. If Pipes doesn't offer some functionality you need, you can now write a web service that does and connect it to the system.

Their example code is in Java, but it didn't take much effort for me to get one working in PHP. Just install the JSON PECL Package and use code like the following: