Question

I have heard a few people make the comment that the default controller/provider for Entity Framework data in the new ASP.NET WebAPI (DbDataController) is not, strictly speaking, a REST based service, but more like an RPC-style service. I understand that the WebAPI framework allows you to make any kind of HTTP service, REST or otherwise, but can someone explain to me specifically what it is about the service exposed by a DbDataController that makes it not a true REST service?

Answer 1

The REST architectural style describes the following six constraints applied to the architecture, while leaving the implementation of the individual components free to design:

Client–server

A uniform interface separates clients from servers. This separation of
concerns means that, for example, clients are not concerned with data
storage, which remains internal to each server, so that the
portability of client code is improved. Servers are not concerned with
the user interface or user state, so that servers can be simpler and
more scalable. Servers and clients may also be replaced and developed
independently, as long as the interface between them is not altered.

Stateless

The client–server communication is further constrained by no client
context being stored on the server between requests. Each request from
any client contains all of the information necessary to service the
request, and any session state is held in the client. The server can
be stateful; this constraint merely requires that server-side state be
addressable by URL as a resource. This not only makes servers more
visible for monitoring, but also makes them more reliable in the face
of partial network failures as well as further enhancing their
scalability.

Cacheable

As on the World Wide Web, clients can cache responses. Responses must
therefore, implicitly or explicitly, define themselves as cacheable,
or not, to prevent clients reusing stale or inappropriate data in
response to further requests. Well-managed caching partially or
completely eliminates some client–server interactions, further
improving scalability and performance.

Layered system

A client cannot ordinarily tell whether it is connected directly to
the end server, or to an intermediary along the way. Intermediary
servers may improve system scalability by enabling load-balancing and
by providing shared caches. They may also enforce security policies.

Code on demand (optional)

Servers are able temporarily to extend or customize the functionality
of a client by the transfer of executable code. Examples of this may
include compiled components such as Java applets and client-side
scripts such as JavaScript.

Uniform interface

The uniform interface between clients and servers, discussed below,
simplifies and decouples the architecture, which enables each part to
evolve independently. The four guiding principles of this interface
are detailed below.

http://en.wikipedia.org/wiki/Representational_state_transfer#Constraints

“The only optional constraint of REST architecture is code on demand. If a service violates any other constraint, it cannot strictly be considered RESTful. DbDataController class exposes Entity Framework models as HTTP services. These services have a great feature overlap with WCF Data Services, such as CRUD support, metadata and request batching. They even partially mimic OData’s query string format.But these services follow the RPC style they’re not RESTful and they don’t use OData.” A qoute from this site:

WCF Data Services and ASP.NET Web API