The SQL Server Data Services (SSDS) team promotes free-form (schemaless) containers and entities as one of SSDS’s primary features.
However, there have been many brief mentions of schemas being included in future SSDS versions (sprints). For example, the SSDS team’s Sprint 2 goes live post of May 26, 2008 includes the following bulletpoint for key features added in Sprint 2:
b. Multiple B-Trees - this will allow us to deploy schemas as we move toward supporting schemas in SSDS
(The SSDS team’s Soumitra Sengupta mentioned in his Philosophy behind the design of SSDS and some personal thoughts post of June 27, 2008 that “Sprint 3 [is] winding down.”)
Channel9’s Istvan Cseri and Nigel Ellis: SQL Server Data Services Architecture interview by SSDS evangelist Ryan Dunn posted April 7, 2008 contains quite a bit of useful (and previously unpublished) information about SSDS architecture.
Following is a transcript I made of Nigel Ellis’s remarks about SSDS’s schemas:
00:29.08: Over the past three or four years, there's been a big investment in the SQL [Server] space in something called the Entity Data Model, where we've got the regular relational model and and we have a high-level model built on top of that. We think of modeling customers, purchase orders, contacts and things like that. There's a whole set of tooling and schema design work that's going on [in] the SQL Server division to make those things approachable and easy to use. ...
For those of you who know the ADO.NET Data Services Framework, that is essentially using the EDM Data Model. You take something that's expressible in EDM terms and make it accessible to open Internet protocols.
00:30:00 So as we evolve our service around the notion of what we call flexible entities, those are the same entities that are in EDM. EDM today doesn't really speak very much to flexibility and open content—Property Bags, if you will—but we’ve been working with the EDM architects as to how that can be extended and accommodated with the same set of with the same set of schema design tools and protocols. And, as I mentioned, the schemas in the SSDS service heads are essentially going to be EDM schemas, EDM types, and EDM relationships. [Emphasis added.]
That statement leads me to believe that SSDS will support complete object graphs in the (hopefully near) future. It also reinforces my prediction that Entity Framework and EDM will dominate Microsoft’s data platform strategy for the next several years.