Alternate way to invoke a REST API using WCF

HttpClient

The typical way to access a REST API is using the HttpClient. Create a HttpClient object. Pass in request headers. Call the PostAsync method with the URL and the request body. Use await keyword to wait for the response. Get the message as a JSON string. Use JavaScriptSerializer to convert the JSON to a C# object.

async Task<int> GetResultUsingHttpClient()
{
    Uri uri = new Uri("http://localhost/api/Algebra
                      /DoAlgebra?num1=3&num2=4");
    string message = string.Empty;
    using (var client = new HttpClient())
    {
        client.BaseAddress = uri;
        client.DefaultRequestHeaders
            .Accept
            .Add(new MediaTypeWithQualityHeaderValue("application/json"));
        var content = new StringContent("", Encoding.UTF8);
        var response = await client.PostAsync(uri, content);
        message = await response.Content.ReadAsStringAsync();
    }
    var serializer = new JavaScriptSerializer();
    var result = serializer.Deserialize<AlgebraResult>(message);
    return result.AddResult;
}

WCF Client

The alternate way to access a REST client is using WCF. WCF offers webHttpBinding which is used to access any REST API. The WebChannelFactory class uses a ServiceContract interface as template. It accepts the binding and the URL information to create a factory object. The factory object creates the client proxy. Call the DoAlgebra method on the proxy.

int GetResultUsingWCFChannel()
{
    Uri uri = new Uri("http://localhost/AlgebraApi/api/Algebra");
    var binding = new WebHttpBinding();
    var factory = new WebChannelFactory<IAlgebraController>(binding, uri);
    var proxy = factory.CreateChannel();
    var result = proxy.DoAlgebra(3, 4);
    return result.AddResult;
}

Using the WCF client, we call an interface method to invoke the API. Define the interface IAlgebraController as a ServiceContract.

[ServiceContract]
public interface IAlgebraController
{
    [OperationContract]
    [WebInvoke(BodyStyle=WebMessageBodyStyle.Bare,
               ResponseFormat=WebMessageFormat.Xml,
               UriTemplate="DoAlgebra?num1={num1}&num2={num2}")]
    AlgebraResult DoAlgebra(int num1, int num2);
}

Decorate the method with an OperationContract attribute. And WebInvoke attribute. The UriTemplate property has the request URL.

I prefer the WCF client to call an API. Using WCF client, we use an interface method to do a POST operation. This is much better than using HttpClient. The WCF Client approach makes it easy to write unit tests for the code.