What is OData?

OData is an acronym of Open Data Protocol, as the name suggests OData is a protocol to standardize the way data is shared between various applications. The OData Protocol aims in standardizing data access between applications in such a way that any application can read data from any provider without the knowledge of the underlying storage format.

OData provides a standard data model to represent the data and a standard protocol which can be used by client applications to request data from the provider. To standardize the process of data sharing, OData uses some of the standard web technologies HTTP, ATOM and JSON for data sharing.

The OData Data Model is based on the Entity Data Model, and provides a standard representation for the data at the publishers end.

The OData Service implements the OData protocol and exposed the data provided by the publisher through a set of end points, the OData Service abstracts the actual data model from the client and exposes data through the endpoints. The Service extracts data from the underlying source which could be a database, file, list etc and

OData Protocol, these are a set of HTTP requests based on REST. These requests include CRUD (create/read/update/delete) operations with OData query to place request to the OData service. The OData service receives these requests processes them and sends back the appropriate data in XML based Atom (Atom Publishing Protocol) format or text based JSON (JavaScript Object Notation) format.

OData client libraries, these are optional libraries which can be used to simplify making calls to OData Services, since the OData Protocol is based on the standard HTTP REST format, we can place requests directly even without using these client libraries. These libraries also help in processing the response which was received after placing requests.

To know more about OData refer the OData site and Microsoft’s OData page.
http://www.odata.org/
http://msdn.microsoft.com/en-us/data/hh237663