Jim O’Neil has written a great blog that introduces you to the Data as a Service codenamed “Dallas”.
Dallas is essentially a repository of data repositories, a service - built completely on Windows Azure - that allows consumers (developers and information workers) to discover, access, and purchase data, images, and real-time services.
Developers can access “Dallas” via REST-based APIs and Atom feeds or in raw format (as many of the content providers had made available pre-“Dallas”). The web-accessible “Dallas” Service Explorer (shown below) allows the consumer to explore the data as well as the HTTP URLs that are constructed and executed to retrieve the data set based on the user-provided parameters.
Since the data services are accessed via standard protocols (REST, HTTP, Atom), “Dallas” can be used by a vast variety of clients – PHP, Ruby, Java, etc. – in addition to .NET, of course. For .NET developers, the Service Explorer offers a convenient option to generate a C# proxy class that essentially provides a wrapper for the HTTP/REST API.
Current data providers (offering trial periods of access) include:
Other content providers coming soon include CitySearch, ESRI, and NAVTEQ. If you happen to be a content provider yourself, contact the “Dallas” team for partnership opportunities.
If you want to dig in yourself, visit Jim's detailed blog post on “Dallas”.