Now that Elgg 1.0 is finally out of the door, I think it is time to talk a little bit about about some of the more advanced features - namely APIs and data formats!
Elgg 1.0 provides a number of ways at getting at your data, including a number of natively supported data formats; including OpenDD (of course), JSON, PHP, and of course RSS.
If you're putting together a mashup, you can use these views very simply. You may have noticed when you're looking at a page with a list of items on it, that there are buttons in the top left which link to either a RSS or an OpenDD view.
Now when you click on one of those you'll see your data presented in an entirely different way. Now one of the fun things you can do is change that by altering the "view" parameter, for example "view=json" to get a JSON view.
You can export individual items of data (that you have access to) in different ways by visiting the "export" url. For example, to export GUID 1 (which will almost certainly be the first site you set up) visit:
http://mysite.com/export/opendd/1/
Of course, if you replace "opendd" with "json" or "php" you can see this data presented in an entirely different way. Additionally, you can also add support for other formats, as I discussed in a previous article.
On top of that, there is an API system where plugin writers can export a function as public. These functions can then be called via a rest-like api (discussed in more detail here).
You can then select how you want to then see that data - whether its PHP, XML or JSON etc.
So, in a nutshell, Elgg has some quite powerful tools for quickly and easily creating some pretty funky mashups. Have fun!
