1. Plugins for 3rd-party websites
2. Graph API
3. OpenGraph protocol
1. plugins for 3rd-party websites
This includes:
Activity stream plugin – allows other website to add Facebook “news feed” to their site
Social bar plugin – allows other website to add barlet at bottom of their site. Chat included.javascript:void(0)
Like plugin – allows other website to add Facebook “Like” button
Login plugin – can show which of your friends have login to this site.
Recommendation plugin
2. Graph API
Facebook have overhauled their api. The so-called "Graph" api is now the way for apps to access all api.
http://developers.facebook.com/docs/api
3. OpenGraph protocol
This requires some explanation.
OpenGraph protocol specifies a set of structured meta data that can be more easily understood and categorized by machines. Once a 3rd-party website embed these data, it allows facebook to include the site and these data as part of the Facebook OpenGraph.
Eg. IMDB website can use OpenGraph protocol to describe a movie object
<html xmlns:og="http://opengraphprotocol.org/schema/"
xmlns:fb="http://developers.facebook.com/schema/">
<head>
<title>The Rock (1996)</title>
<meta property="og:title" content="The Rock" />
<meta property="og:type" content="movie" />
<meta property="og:url" content="http://www.imdb.com/title/tt0117500/ "/>
<meta property="og:image" content="http://ia.media-imdb.com/rock.jpg" />
...
</head>
...
</html>
When this is included, Facebook can store this site as an object in the OpenGraph. And that object will have these properties: title="The Rock", type="movie", url="...", image="...".
How is OpenGraph significant?
If facebook's vision of opengraph succeed, they could be the connector of the web!
In terms of the flexibility and coverage, what facebook wants to do with OpenGraph may seem like a baby step comparing to what Semantic Web wants to do. Facebook only define a small set of predefined meta data. While semantic web have various powerful ontologies already defined. However, with facebook's reach and appeal, facebook might finally get a lot of website owners to embed structured metadata, which would be a significant milestone for semantic web in any case. This may turn out to be a giant leap for semantic web.
