Microsoft Revamps SDS Cloud Database

Following months of criticism that its cloud-based SQL Data Services lacked the horsepower for enterprise-grade applications, Microsoft today said it is scrapping the effort and moving to a pure relational model instead.

Microsoft plans to offer a pure relational database in the cloud by exposing its Tabular Data Stream (TDS) over-the-wire protocol for accessing SQL Server via its forthcoming Azure Services Platform. The move reverses the existing plan to offer SDS via the REST Web services interface, which testers have been panning over the past four months.

The announcement, which was not expected before next week's MIX09 conference in Las Vegas, was issued on Microsoft's SQL Server blog

Microsoft said it will support traditional relational database capabilities, including SQL queries and support for relational schema and stored procedures. While the company maintains that was always the plan, it said it will no longer expose those capabilities by requiring the REST Web services interface.

"They are saying instead of creating a Web service interface, they are basically exposing SQL Server over HTTP," said Andrew Brust, chief of new technology at consulting firm twentysix New York and a Microsoft regional director.

By eliminating that layer and exposing TDS to SQL Server over the cloud, developers will be able to move data-driven code developed in Microsoft's T-SQL language to SDS, Microsoft said.

Microsoft expects SDS to become the first relational database service to support existing T-SQL development. While Amazon offers a hosted SQL Server offering through its cloud-based EC2 service, it does not currently offer native relational capabilities, according to Brust.

"What Amazon does is they let you spin up a virtualized Windows servers, and you can put SQL Server on it, and they will make sure you are appropriately licensed to do that," Brust said.

Microsoft said it will transition its SOAP and REST-based Authority Container Entity (ACE) data model. Microsoft is suggesting that those who want to use REST-based programming for applications that do not require an RDMBS can use the Azure table storage. "You can still access your relational data (located on premises or in the cloud) via HTTP/REST using the ADO.NET Data Services framework," wrote Microsoft Senior Program Manager David Robinson in a blog posting today .

'Acceleration' of Plans
For its part, Microsoft is positioning the change as an "acceleration" of its existing plans. "The universal feedback we received from our TAP partners and other early adopters was the need for a relational database delivered as a service," Robinson noted. "Developers will be able to very easily provision themselves a logical server and database and begin developing against it immediately using the existing tools and technologies that they are accustomed to."

Said Brust, "It seems they have cleared away some overlap and they've made it closer to what developers are used to and a lot purer to the SQL Server brand."

Microsoft had recently begun dropping hints that it would retrofit SDS to offer relational capabilities. While it was not clear how far the company would go, Robinson said last week in another a blog post prefacing today's news that Microsoft "will be unveiling some new features that are going to knock your socks off."

For one critic of the existing SDS, that's what Microsoft did. "It did knock my socks off," said

OakLeaf Systems principal Roger Jennings, who had tested the service and found it was unable to offer the scalability of the existing SQL Server. "They offered some pseudo-relational features but they didn't offer the ones that people really wanted," Jennings said in an interview.

SDS also offered little that was different from its Azure Tables for storage and SQL Server Tables using the Entity Attribute Value (EAV) model, Jennings added. "It was really confusing the troops," he said. "They gave up on EAV."

In a blog posting today, Jennings described Microsoft's move as a "mid-course reversal," not a correction.

Microsoft said SDS with TDS support would be available for testing by mid-year and commercially available by the end of the year.

About the Author

Jeffrey Schwartz is editor of and news editor of Visual Studio Magazine.