Last week at Mix07 Microsoft announced a project code named Astoria.
The technology code named Astoria is a technology that enables applications to expose data as a data service that can be consumed by web clients within corporate networks and across the internet. The Astoria data service is reachable over regular HTTP requests, and standard HTTP verbs such as GET, POST, PUT and DELETE are used to perform operations against the service. The use of web-friendly technologies make Astoria ideal as a data back-end for AJAX-style applications, Rich Interactive Applications and other applications that need to operate against data that lives across the web.
Pablo Castro has some more in depth posts up on his blog on Astoria:
For developers this is interesting as they will be able to use flexible data services that are naturally integrated with the web, use URIs to point to pieces of data and utilize simple, well-known, formats to represent the data, such as JSON and plain XML. Astoria provides web developers with a simple and clean way to access data when developing Ajax or Silverlight applications, using the familiar HTTP verbs such as GET, POST or DELETE, to point and manipulate their data.
There is currently an online service preview of Astoria available at http://astoria.mslivelabs.com/. So you can consume the web data service API directly from there. If you want to install the bits yourself to try them out, you can donwload them together with the documentation and samples at Microsoft Project Codename "Astoria" CTP. The Astoria downloadable bits can be used to build data services that are entirely contained within a single computer or network and the online service preview lets you create online stores that are hosted by Microsoft and that are accessible over the internet. The payload format for the Astoria service is controllable by the application, but all options are simple, open formats such as plan XML and JSON.