Open Graph protocol". Facebook showed its market power by rolling it out immediately with 30 large partner sites that are allowing users to "Like" them on Facebook. Facebook's vision is that web pages representing "real-world things" such as movies, sports teams, products, etc. should be integrated into Facebook's social graph. If you look at the right-hand column of this blog, you'll see an opportunity to "Like" the Blog on Facebook. That action has the effect of adding a connection between a node that represents you on Facebook with a node that represents the blog on Facebook. The Open Graph API extends that capability by allowing the inclusion of web-page nodes from outside Facebook in the Facebook "graph". A webpage just needs to add a bit of metadata into its HTML to tell Facebook what kind of thing it represents.
I've written previously about RDFa, the technology that Facebook chose to use for Open Graph. It's a well designed method for adding machine-readable metadata into HTML code. It's not the answer to all the world's problems, but it can't hurt. When Google announced it was starting to support RDFa last summer, it seemed to be hedging its bets a bit. Not Facebook.
http://opengraphprotocol.org/ and a google group at http://groups.google.com/group/open-graph-protocol, there are as yet no topics approved for discussion in the group. [Update- the group is suddenly active, though tightly moderated.]
Nonetheless, websites that support Facebook's metadata will also be making that metadata available to everyone, including Google, putting increased pressure on websites to make available machine readable metadata as the ticket price for being included in Facebook's (or anyone's) social graph. A look at Facebook's list of object types shows their business model very clearly. Here's their "Product and Entertainment" category:
At Twitter's "Chirp" conference, Twitter announced that it will add "Annotations" to the core Twitter platform. The description of Twitter annotations is characteristically fuzzy and undetermined. There will be some sort of triple structure, the annotations will be fixed at a tweet's creation, and annotations will have either 512 bytes or maybe 1K. What will it be used for? Who knows?
meeting. He boasted about how Twitter users invented hashtags, retweets and "@" references, and Twitter just followed along. Now, Twitter hopes to do the same thing with annotations. Presumably, the Twitter ecosystem will find a use for Tweet annotations and Twitter can then standardize them. Or not. You could conceivably load the Tweet with Open Graph metadata and produce a Facebook "Like" tweet.
Many possibilities for Tweet annotations, underspecified as they are, spring to mind. For example, the Code4Lib list was buzzing yesterday about the possibility that OpenURL references (the kind used in libraries to link to journal articles and books) could be loaded into an annotated tweet. It seems more likely to me that a standard mechanism to point to external metadata, probably expressed as Linked Data, will emerge. A Tweet could use an annotation to point to a web page loaded with RDFa metadata, or perhaps to a repository of item descriptions such as I mentioned in my post on Linked Descriptions. Clearly, it will be possible in some way or other to put real, actionable literature references into a tweet. Whether it will happen, it's hard to say, but I wouldn't hold my breath for Facebook to start adding scientific articles into its social graph.
Although there's a lot of common capability possible between Facebook's Open Graph and Twitter's Annotations, the worldviews are completely different. Twitter clearly sees itself as a communications media and the Annotations as adjuncts to that communication. In the twitterverse, people are entities that tweet about things. Facebook sees its social graph as its core asset and thinks of the graph as being a world-wide web in and of itself. People and things are nodes on a graph.
While Facebook seems offer a lot more to developers than Twitter, I'm not so sure that I like its worldview as much. I'm much more than a node on Facebook's graph.