Through it’s API, Google is starting to define its OS for outside developers. The main characteristic of the OS seems to be its web simplicity. Everything has of course a URL. Google defines “kinds”, which are major content types, like “event” or “message”. A message can be an email, a blog entry, a comment or anything like that.
So Google’s services (calendar, mail, …) use a common language and common content types (“kinds”). This promises to be powerful stuff, and as we’ve seen with the opening of Amazon’s S3: we’re just getting started.
Common Elements:”Kinds”: “The collection of elements that together describe a contact is called the Contact “kind.” Some of the elements in the Contact kind are ordinary Atom or RSS elements; others are defined by Google in a namespace called the “Google data namespace.” By convention, the Google data namespace is usually referred to in XML code using the gd: alias; for example, the element that contains a telephone or fax number is . The schema URL for the Google data namespace is http://schemas.google.com/g/2005.
Google defines other kinds as well: Event (a collection of standardized elements that together represent a calendar event) and Message (a collection of elements representing an email message, discussion group posting, blog entry, or other message).”