March 10, 2014March 18, 2014 Dhananjay Kumar , Microsoft MVP , Trainer and Consultant

WCF Web HTTP Service: why and how

Very often I talk on WCF to user groups and find developers confused on various forms of WCF. For example some of the questions I get are as follows

How to create REST Service
Can we create REST and SOAP Service together
What is WCF Web HTTP Service
How Web HTTP Service and WCF REST Service are different to each other
Can I host HTTP Service and REST Service in a console application
Why we need REST and HTTP Services
What kind of security can be applied on REST and HTTP Services and many more questions of this kind

In this post I will answer few of the above questions regarding WCF Web HTTP Services.

By definition, WCF Web HTTP programming model allows services to be exposed on non-SOAP EndPoints and helps to create WEB HTTP Services. Now a question may arise that why we need HTTP Services and what are the advantages of using that.

Mainly HTTP Services are designed and created for wide range of clients. Any application capable of following can be potential clients

Understand HTTP protocols and verbs
Can process URI and URL Schemes
Can work with different types of message and data formats
Perform HTTP Get and HTTP Post operations

Web HTTP Services doesn’t work on SOAP message format however any serilizable type can be returned from Web HTTP Services. Since HTTP Service does not work with SOAP so all WCF Security features cannot be applied on this. However basic Transport level security can be applied to WCF Web HTTP Services.

Let us see how we can create a very basic WCF Web HTTP Service. Create WCF Service Application project from WCF tab to create Web HTTP Service

After creation of project we need to create Service Contract.


 [ServiceContract]
    public interface IService1
    {

        [OperationContract]
        [WebGet]
        string HelloGet(string   name);

        [OperationContract]
        [WebInvoke]
        string  HelloPost(string  name);
       
    }

Above I have created very basic service. Service contains only two methods. One method will work on HTTP GET and other will work on HTTP POST operation. There are restrictions on passing parameters in query string. For example string can be passed in query parameter.


public class Service1 : IService1
    {       

        public string HelloGet(string name)
        {
            return "Hello GET " + name; 
        }

        public string HelloPost(string name)
        {
            return "Hello POST" + name; 
        }
    }

Above Service Contract is implemented as below. It’s very simple implementation in which service is returning string with concatenating of input string parameters.

Now there are various ways WCF WEB HTTP Services can be hosted and its EndPoint can be configured. You can configure and host service

In IIS
In Windows Services Application
In Managed Application like Console Application
Windows Azure Services

In this post let us learn how EndPoint can be configured for Web Server hosting like IIS. It’s very simple to configure EndPoints for HTTP Services. You can use Factory method System.ServiceModel.Activation.WebServiceHostFactory to create WEB HTTP Service.

You can fetch service from browser by navigating to URL as below. Keep in mind that port number could be different in your scenario.

http://localhost:55400/Service1.svc/HelloGet?name=dj

You can notice that we are passing input dj as string in query parameter. Response from service will be as below,

Another way service can be configured and hosted in a console application. In Console Application first you need to add reference of System.ServiceModel and System.ServiceModel.Web in the project.


using System;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceModel.Web;
using Demo1;

namespace ConsoleAppHostingService
{
    class Program
    {
        static void Main(string[] args)
        {
            WebServiceHost host = new WebServiceHost(typeof(Service1), new Uri("http://localhost:8989/"));
            ServiceEndpoint endpoint = host.AddServiceEndpoint(typeof(IService1), new WebHttpBinding(), "");
            ServiceDebugBehavior sdb = host.Description.Behaviors.Find<ServiceDebugBehavior>();
            sdb.HttpHelpPageEnabled = false;
            host.Open();
            Console.WriteLine("Service is running");
            Console.WriteLine("Press enter to quit...");
            Console.ReadLine();
            host.Close();

        }
    }
}

Few points about above hosting code are as follows

WEB HTTP Service should be hosted in a WebServiceHost instance.
WebHttpBinding is used to created HTTP Service
Help page is disabled

On running Console Application, service can be accessed on URL passed in WebServiceHost instance

In this way you can create WCF WEB HTTP Service. In further posts we will learn how to consume this service in various kind of clients and work with different kind of data format. I hope this post will help you.

October 8, 2012November 12, 2012 Dhananjay Kumar , Microsoft MVP , Trainer and Consultant

ASP.Net Web API Service in Windows Phone: Part 4 of Many

Creating First HTTP Service using ASP.NET Web API: Part1 of Many

Consuming ASP.NET Web API Service using HttpClient: Part2 of Many

How to Self-Host ASP.Net Web API: Part 3 of Many

In this post we will consume ASP.Net Web API HTTP Service in Windows Phone Application. If you do not specify header information in HTTP request then by default ASP.Net Web API service returns JSON data. So essentially there are three steps involved in consuming HTTP Service from ASP.Net Web API in Windows Phone Application.

Make a HTTP Request
Read data from HTTP Response
Parse returned JSON data and bind data to data bound control

In this post we are going to consume service created in this POST

I have created a Windows Phone Application by choosing target framework 7.1. We are going to display Bloggers Data returned from ASP.Net Web API service in a ListView. Essentially we are going to consume a JSON Data from a HTTP Service. For that add below references in the project.

We are going to de-serialize JSON data using DataContractJsonSerializer class. We need to create a class at client side representing Bloggers entity from the service. Let us create a class called BloggersClient. We will de-serialize JSON data returning from the HTTP service in this object of this class.


namespace WindowsPhoneClient
{
public class BloggersClient
{
public string Id { get; set; }
public string Name { get; set; }
public string AreaOfIntrest { get; set; }

}
}

Once the client class is in placed add following references,

We are going to download JSON data from ASP.Net Web API service using WebClient class. Make sure that you are passing URL of your HTTP Service.

In the completed event, we will parse returned JSON using DataContractJsonSerializer class. In following code,

Creating MemoryStream form returned result
Creating object to de-serialize the returned JSON data
Reading de-serialized data object in List of BloggersClient
Setting List of BloggerClient as ItemSource of ListBox. On the XAML we have put a ListBox with name lstBloggers.

Code behind to load data from ASP.Net Web API HTTP Service on page load of the application and s display in ListBox is as following


using System;
using System.Collections.Generic;
using System.Net;
using Microsoft.Phone.Controls;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;

namespace WindowsPhoneClient
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
WebClient proxy = new WebClient();
proxy.DownloadStringCompleted +=
new DownloadStringCompletedEventHandler(proxy_DownloadStringCompleted);
proxy.DownloadStringAsync(new Uri("http://localhost:39192/api/Bloggers"));
}

void proxy_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
Stream s = new MemoryStream(Encoding.Unicode.GetBytes(e.Result));
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(List<BloggersClient>));
List<BloggersClient> result = (List<BloggersClient>) ser.ReadObject(s);
lstBloggers.ItemsSource = result;
}
}
}

On the XAML, we have put ListBox control do bind data from HTTP Service in the control.

If you are not aware of Data Binding in ListBox then watch a quick Video here


<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>

<!--TitlePanel contains the name of the application and page title-->
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
<TextBlock x:Name="ApplicationTitle" Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}"/>
<TextBlock x:Name="PageTitle" Text="ASP.Net Web API" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
</StackPanel>

<!--ContentPanel - place additional content here-->
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<ListBox x:Name="lstBloggers">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Name}" Style="{StaticResource PhoneTextTitle2Style}" />
<TextBlock Text="{Binding AreaOfIntrest}" Style="{StaticResource PhoneTextAccentStyle}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Grid>

Now press F5 to run the application. You should able to get Bloggers detail from ASP.Net Web API service in Windows Phone Application.

I hope you find this post useful. Thanks for reading.

March 7, 2012July 6, 2012 Dhananjay Kumar , Microsoft MVP , Trainer and Consultant

Consuming ASP.NET Web API Service using HttpClient: Part2 of Many

Read Part 1 Here

I am in love with ASP.NET Web API hence I started writing on the same. In first part of this blog series I have written Creating First HTTP Service using ASP.NET Web API: Part1 of Many.

In this post I will show you how you could consume service created in previous blog post in a managed application?

Service is hosted at http://localhost:14892/api/Bloggers

To download JSON data from service as string you can use WebClient class from System.Net as below. In below code essentially we are downloading JSON data as string from the service.


using System;
using System.Net;

namespace ConsoleApplication39
{
class Program
{
static void Main(string[] args)
{
using(WebClient proxy = new WebClient())
{
var response = proxy.DownloadString("http://localhost:14892/api/Bloggers");
Console.WriteLine(response);
Console.ReadKey(true);

}
}
}
}

As output you will get downloaded string on console

In above code while making call to service; we are not providing any header type and as response we are getting JSON since default serealizer of ASP.NET Web API is JSON serealizer. If you want to get XML data as response then you need to set Accept Header type to XML. Below code will download XML data from the service.


using System;
using System.Net;

namespace ConsoleApplication39
{
class Program
{
static void Main(string[] args)
{
using(WebClient proxy = new WebClient())
{
proxy.Headers.Add(HttpRequestHeader.Accept, "application/xml");
var response = proxy.DownloadString("http://localhost:14892/api/Bloggers");
Console.WriteLine(response);
Console.ReadKey(true);

}
}
}
}

On Console you will get expected XML as below,

Other than WebClient class, you can use HttpClient class. It is rich Http Client for .NET. It exposed the API to

Receive HttpResponseMessage
Send HttpRequestMessage

To work with HttpClient class you need to add below DLL in the project. You can download these dll from here

You can download data as JSON array using HttpClient as below. We are downloading data asynchronously and using properties name printing them.


using System;
using System.Net.Http;
using System.Json;

namespace ConsoleApplication39
{
class Program
{
static void Main(string[] args)
{

HttpClient proxy = new HttpClient();
proxy.GetAsync("http://localhost:14892/api/Bloggers").ContinueWith((r) =>
{
HttpResponseMessage response = r.Result;
response.Content.ReadAsAsync<JsonArray>().ContinueWith(
(a)=>
{
foreach(var w in a.Result)
{
Console.WriteLine(w.ValueOrDefault("Name").ToString());
Console.WriteLine(w.ValueOrDefault("Intrest").ToString());
}
});

});

Console.ReadKey(true);

}

}
}

You will be getting output on console as below.

Now question may come to your mind that why to use HttpClient over WebClient? You can use same instance of HttpClient to make as many call to service as you want. HttpClient allows you to configure headers extension etc.

In this way you can consume an Http Service created using ASP.Net Web API in a managed client. I hope this post is useful. Thanks for reading.

Follow @debug_mode

March 3, 2012July 6, 2012 Dhananjay Kumar , Microsoft MVP , Trainer and Consultant

Creating First HTTP Service using ASP.NET Web API: Part1 of Many

In this post I will give you basic understating of creating HTTP Services using ASP.NET Web API. Here I am assuming that you are aware of basic ASP.NET MVC.

To work with ASP.NET Web API, you need to install ASP.NET MVC 4.0. Download ASP.NET Web API from here and install it from Web Installer.

After installation create a new project choosing ASP.NET MVC 4 Web Application as project type.

Next choose Web API as template.

On examining project structure you will find it is exactly as usual ASP.NET MVC project structure. Let us go ahead and add a MODEL. For that right click on the Model folder and add a class. Let us add a model called Blogger

Blogger.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace firstwebapiapplication.Models
{
public class Blogger
{
public int Id { get; set; }
public string Name { get; set; }
public string Intrest { get; set; }
}
}

After adding Model let us go ahead and add Controller. There are two differences between Controller of usual ASP.NET MVC Controller and ASP.NET Web API Controller.

ASP.NET Web API Controller returns data not view
ASP.NET Web API Controller is derived from ApiController class.

Now go ahead and add a Controller called BloggerController. For that right click on Controller folder and add a controller.

Choose Empty Controller as Scaffolding options.

Next you need to change the class controller is inheriting. Change Controller to ApiController.

Controller class needs to inherit ApiController class from System.Web.Http namespace. Let us add a function to return information about Bloggers.

BloggerController.cs


using System.Collections.Generic;
using firstwebapiapplication.Models;
using System.Web.Http;

namespace firstwebapiapplication.Controllers
{
public class BloggersController : ApiController
{
//
// GET: /Bloggers/



public IEnumerable<Blogger> GetAllBloggers()
{
return new List<Blogger>
{
new Blogger(){ Id= 1,Name="DebugMode",Intrest="ASP.NET Web API"},
new Blogger(){ Id= 2,Name="KodefuGuru",Intrest ="C Sharp"},
new Blogger(){ Id= 3,Name="ActiveNick",Intrest = "Windows Phone" },
new Blogger(){ Id= 4,Name= "GBLOCK ", Intrest ="REST"},
new Blogger(){ Id= 5,Name = "WadeWegner",Intrest = "Windows Azure " }
};
}

}
}

By this point you have created HTTP Service. Press F5 to host the service on Cassini server.

And you will get a file to download

Next we can consume it in any client. In later post I will show you to consume in JavaScript client and Windows Phone as well. I hope this introductory blog post is useful to get started with ASP.NET Web API. In next post we will get into consuming ASP.NET WEB API Services in various clients

Follow @debug_mode