Saturday, May 3, 2008

RESTful Web Services and the WCF Web Programming Model

REST (Representational State Transfer) is not a new thing to the web service world; you can find a lot about what it is on the net, but for formality...REST is an architectural style (not a standard) it simply means web services are identified as resources and each operation as a unique URI assigned to it.You invoke the object's operation using the HTTP verbs like GET, POST etc...
Most web services are being shifted to using this style, for an example yahoo web services use REST. But some companies continue to have a REST service in addition to the SOAP based service.
One of the advantages of using REST over SOAP based services is that REST is light weight, as there is not much XML markup; for an example, REST does not use the SOAP header which is chunky.
Another benefit of REST is that the client accessing the service does not need special SOAP tool kit to use the service, as the service operation is identified as a URI, it is just a matter of accessing it like a web page in a browser.
REST responses can also be of variety, currently XML, raw binary data and JSON responses are supported.
.NET provides a way to create RESTful web service through the WCF web programming model. This basically allows you to build your RESTful services on top of WCF; this also means that you can expose your current WCF service as a RESTful service by adding certain attributes to you operation contracts and exposing it on a different endpoint.
WCF 3.5 supports a webHttpBinding for this purpose and also a WebServiceHost class to host your RESTful service.So how is this done?.. look at the code sample below.

[ServiceContract]
public interface ICalculator
{
[OperationContract]
[WebGet]
int Add(int num1, int num2);
}

In addition to the general {OperationContract}, a [WebGet] attribute is added, this just signals the frame work that the Add method is exposed as a RESTful operation as well.On the next post I will show you how we can create a RESTful service in WCF.


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