Its a subset of RDFa which focuses on a single schema and a single location where this schema can be applied:
This is why we started working with it at our company. Simplicity and of course being a standard proposal signed under the OWFa agreement: Open for anyone to use.
So we have been testing interoperability on enterprise software systems. How hard is it to add these ogp meta tags ? For some systems like SugarCRM we have the source code and for some other like Sharepoint we do not.
In addition, our target audience are system administrators, not just developers so we are interested in finding the simplest solution that feels more natural in their environment.
From my experimentation I have definitely found some challenges dealing with this more closed enterprise software. No access to edit the html on the head. No access to dynamic data from the head.
So I decided to try more consumer facing products like wikis, blogs, etc hoping to encounter less resistance.
Today I was testing adding some ogp markup to this blog and found that unlike other systems I have been working with lately it allowed my to easily modify the HEAD.
The images I want featured when I share blog entries with the world will come from each blog entry and will be carefully chosen to capture the essence of the piece.
Naturally the first solution I thought of was Microformats as these can be added in context. The problem with microformats is that they don't have a lot of common properties between the different types of objects.
So one proposal would be to add the concept of a representative image to microformats but in the essence of time I searched some more and remembered something about microdata in HTML 5.
When I first saw Microdata presented I wondered why there was another specification talking about semantics. There is already RDFa... but in taking a closer look I am quickly seeing how useful microdata will be based on its simplicity.
The beauty of microdata is that it does not concern itself with imposing a schema. It does one job and it does it well.
Schema is optional. No namespaces. Hurray ! Much more suited for doing inline representation of objects.
Looking at the Open Graph Protocol I realize its more of a schema that can easily be translated into a microdata vocabulary.
Therefore we have now shifted gears to add support in our product for parsing microdata with the open graph protocol as a vocabulary. No more need to hack in semantics. The solution is in the HTML 5 specification. In addition will be rolling our support for more vocabularies based on the needs of our users.