SQL Data Services (SDS) has been on the radar since MIX08, when it was first announced as an online data storage and query processing service that could be accessed using the standard internet protocols. It has come a long way since then. At MIX09, Microsoft demonstrated some of the newest capabilities of SDS — specifically its new relational database capabilities.
That's right, Microsoft will offer a relational database in the Azure cloud.
A Cloud-Based Relational Database Service
Based on a lot of feedback, Microsoft has decided to offer a fully relational database service in the Windows Azure cloud. Developers will be able to provision a logical server and database, and develop against it using the tools they have today. In fact, it is supposed to be easy to create your database on premise and then move it to the cloud by just changing the connection string.
What this means is that SDS will support Transact-SQL over TDS (Tabular Data Stream) protocol. TDS is the published protocol used to communicate with SQL Server today.
In its first incarnation, SDS will only support core RDBMS capabilities but the expectation is that more advanced functionality such as Reporting, Analytics, ETL and more will come.
What About REST Protocol?
The ACE (Authority, Container, Entity) data model which is the current model used for SDS will stop being supported at some point. One of the key advantages of this data model was that you could access the data using the REST protocol.
Microsoft has confirmed though, that REST will still be in the picture with the relational data model. Actually you will be able to access data both on premise and in the cloud via HTTP/REST using ADO.NET.
With the TDS protocol, developers can also communicate with the data services using traditional approaches including ADO.NET, ODBC and JDBC.
SDS Data Model
SQL Data Services is targeted at just about everyone who wants a data service in the cloud. SMBs, developers building Web 2.0 and ASP.NET apps that want a highly available service with a pay-as-you-grow pricing model, even SaaS ISVs.
The new version of SDS with TDS support is expected to be available as a public CTP sometime around the middle of this year and then commercially available before the end of the year. You can learn more about SQL Data Services on MSDN and one the Azure Platform website.