Hierarchical RSS 

Rich Site Summary (or RSS as it is popularly known) has so far been flat-structured. That means we could have a flat list that didn't have any relationship to anything above or below it. This is okay if you're trying to blog or simply publish a list of all new things (downloads, news and so forth) you have on your website. 



In fact, this is how and why it is being used everywhere. And, increasingly, blogs aren't just text anymore. First came the ability to add pictures and video. Today, almost anything can be a blog by itself and it is simply not necessary to add text to call it a
'blog'!

The why and how



But RSS is just a bunch of XML data, and XML itself is a structured and layer-enabled format. So, why not have RSS that's layered too? This is exactly what the makers of EVDB (Events and Venues Database) thought about and implemented. They have used a mix of scripting (Perl and PHP), with databases (PostgreSQL and My SQL) to render this new form of RSS. What this RSS does is to help relate one set of RSS data with another set. While this is not directly useful in the existing applications of RSS-which are primarily news and blogs-but it opens up possibilities of new applications on this new avatar of RSS. As a result, calendars and collaboration tools can now be run on

RSS.

Applications



Calendars of events, when in flat-RSS can only convey one event. So, if we add a workshop event for today, there would be no way to add or support sub-events (your detailed agenda) with this RSS. However, with H-RSS (Hierarchical RSS) you could have one main entry that describes the entire workshop and sub-rows that correspond to separate events or tracks. 

In collaboration tools too, H-RSS could be used to provide meaning and depth to shared information by adding more attributes and tracking-links (original file, links to all versions of the file and so on). Smart calendars can also be centered on H-RSS, that's intelligent enough to track-back (a blog term for 'link') to others.

Communication in the form of e-mail has so far not been touched by RSS. H-RSS can be used to provide linked e-mails such as that provided by Gmail. In such 'conversation mail', it is possible to track the entire series of messages and replies as a single continuous entity, not possible with

flat-RSS.

Compatibility with existing RSS readers is a big issue. And this is why, the makers of EVDB have decided to output conventional flat-RSS when you request an RSS stream, till a client is developed for the H-RSS feeds. 

Media-watchers would note that this has already actually been implemented with a lot of success for photographic files, by Flickr.com (ludicorp). Flickr allows registered users to upload sets of photographs, assign them keywords and share them with everyone on the Web. It even supports features such as relating two photos to each other using their keywords and other attributes. On their website, it also allows you view a set as a slideshow. 

On the advanced side, it lets you blog your photos from your digicam to the website. Photos can be commented on by others and you can perform some basic editing on the site itself (size, rotation) before you download it. One cool feature on Flickr.com is the ability to add tags to pieces of a picture. So, if you uploaded a group photo, you can add each person's name separately and it would show up when someone hovers their mouse over that part of the picture.

Sujay V Sarma