The Open Data Protocol (OData) is a web protocol for querying and updating data. OData applies web technologies such as HTTP, Atom Publishing Protocol (AtomPub) and JSON to provide access to information from a variety of applications, services, and stores. This protocol emerged organically based on the experiences implementing AtomPub clients and servers in a variety of products over the past several years. OData is being used to expose and access information from a variety of sources, including but not limited to relational databases, file systems, content management systems, and traditional web sites. Microsoft has released OData under the Open Specification Promise (OSP) to allow anyone to freely interoperate with OData implementations. We intend on working with the community to move the features of OData into future version of AtomPub or other appropriate standards.
OData is consistent with the way the web works. OData makes a deep commitment to URIs as a means to identify resources (just like the web). OData commits to an HTTP-centric protocol with a uniform interface for interacting with those resources (again, just like the web). OData builds on the conventions over HTTP popularized by AtomPub, which have simplified the process of sharing data, content and information across independently developed systems. OData defines additional conventions that implementations may optionally implement to support basic query and schema information to be exchanged. To simplify integration with HTML and JavaScript clients, OData defines an optional JSON representation of the protocol that complements the XML-based AtomPub format.
Three sets of specifications:
Atom Publishing Protocol: Data Services URI and Payload Extensions
[MC-CSDL]: Conceptual Schema Definition File Format
[MC-EDMX]: Entity Data Model for Data Services Packaging Format
Three Applications which can use it:
SharePoint, Excel (via PowerPoint), SQL Server, and Websphere eXtreme Scale (IBM)
Two services, which are built using it:
http://ogdisdk.cloudapp.net/
http://pinpoint.microsoft.com/en-US/Dallas