Yesterday we heard a session done by Patrick Chanezon about Google’s OpenSocial and while there was not really much new (he mostly showed demos) at least one thing was getting clearer to me. So first my understanding was a bit like Java:
„Write once, run everywhere“
but even David Recordon hinted at the Barcamp session about OpenSocial that not every container for OpenSocial applications might work the same. Some might have more storage space they give you, some have less. And Patrick showed another example at his presentation of where things can differ. He showed the favourite movie field in the MySpace profile which can now be reused by the Flixter application. So indeed the information covered by the OpenSocial API is extended in this case by fields which might not be available on other containers.
Thus the assumption that you write an application only once for all containers is wrong. You might be able to reuse much of your application but you maybe not able to simply copy it over. So Patrick instead said that it’s
„Learn once, write anywhere“
This is maybe important to note.
BTW, good coverage on the Web 2.0 Expo can be found at Berlin Blase (O’Reilly Rader about them).