The SmartStore Web API allows direct access to the data of an online store. It is built on the most recent technologies Microsoft offers for web based data consuming, the ASP.NET Web API and the OData provider. This documentation gives you an overview of how to build an API client, also known as API consumer. It uses C# code, but you can build your consumer in any common programming language. As OData is a standardized protocol, there are a lot of frameworks and toolkits available for various platforms.
The ASP.NET Web API is a framework for building web APIs on top of the .NET framework. It uses HTTP as an application protocol (rather than a transport protocol) to return data based on the client requests. The Web API is able to return the data appropriately based on the media type specified by the request. By default, it provides JSON and XML based responses.
The Open Data Protocol (OData) is a standardized web protocol that provides an uniform way to expose, structure, query and manipulate data using REST practices. OData also provides a uniform way to represent metadata about the data, allowing clients to know more about the type system, relationships and structure of the data.
The Web API is primarily used to exchange raw data. With a few exceptions, further service functions of SmartStore are not accessible via the API. If different data is to be exchanged on a large scale, the more flexible solution may be to use a separate plugin. Such a plugin acts as middleware between SmartStore and your application and can in principle access all service functions of SmartStore.