Introduction

In this article we will see,

• How to create a WCF 4.0 Service
• How to host service in IIS 7.5
• How to consume that in Silverlight 4.0 client
• How to avoid cross domain problems.

For our walkthrough, I am going to create a simple Addition Calculator. User will interact with the Silverlight UI and on the user input a WCF Service hosted in IIS will get called.

Expected Output

When the user will clicks on the + button a WCF service hosted on IIS gets called. The value from two textboxes will be passed as an input parameter to the service and the result will be displayed in the result text box.

How to create the WCF Service

Open Visual Studio, select new project and then from the WCF tab select WCF Service application to create a new WCF service.

Delete the default code created by WCF from IService1 and Service1.svc.cs. Delete the data contract and modify the service contract as below. Just make one operation contract to return a string.

Listing 1: IService1.cs

Now implement the service as below.

Listing 2: Service1.svc.cs

Since we are creating a WCF Service for Silverlight client, we need to modify the endpoint of the service with basicHttpBinding.

As we know Silverlight supports either basicHttpBinding or webHttpBinding. webHttpBinding is essentially for REST based services. We are going to use basicHttpBinding to enable SOAP based WCF service for Silverlight client.

1. Declare the end point with basicHttpBinding.

2. Declare the metadata exchange end point.

3. Define the service behavior

So the service will look like

Listing 3: Web.Config

Hosting in IIS and solving the cross domain problem

Let's see how to host the WCF Service in IIS 4.0

Open the command prompt in administrator mode. To do this, click on the Start button then type RUN in search and then in the Run window type inetmgr to open IIS.

Now you will have IIS opened like below.

Right click on Sites and then click Add Web Site.

Now a window will open.

Give a name of your choice as the site name. I am naming it HostedWcfService.

Now click on select and choose ASP.Net v4.0 from the drop down.

Now in the physical path section, we need to give a physical path for the service. So to get the physical path of the service, right click on the WCF Service project in Visual Studio and click open project in windows explorer. Open the project in windows explorer and from the address bar copy the path and paste it below. Or, just click on the Browse button and navigate to the project folder of the WCF Service.

Now at the Binding section select HTTP. Give any port number. I am selecting port 4567.

Do not give any name as the host name. Leave it blank.

Check the checkbox "Start Web Site Immediately".

Now click OK on the window. Open the Visual Studio command prompt in administrator mode. Right click and select "Run as administrator".

Type the command aspnet_regiis.exe /iru.

You will get the message "Finished Installing ASP.Net 4.0". Now go to inetmgr, and you should be able to see the site you just created in previous steps.

Publishing the WCF Service

Go back to WCF Service.Right click and select Publish.

Upon clicking on Publish a window will open.

Provide a Service URL. You are free to provide any Service URL here. Just make sure the host name is getting resolved. Instead of localhost you can give an IP address or your machine name.

Supply the site name HostedWcfService. We created this site in previous steps.

Leave the credentials group inactive.

Now click on Publish.

You will get the message "Publish Succeeded".

Browsing the service hosted in IIS

Open Inetmgr and right click on site HostedWcfService. Then from Manage Web Site select the Browse option.

When you click on Bowse Site, it will get opened in the browser.

You will get the above error. Just in address bar append Service1.svc with the address to open the service in browser.

http://localhost:4567/Service1.svc

And in browser you will get the service up and running.

So now you successfully created and hosted the WCF 4.0 service in IIS 7.5

Solving the cross domain problem

Right click on WCF Service project and add new item. Select XML file from Data tab.

Give the XML file the name the clientaccesspolicy.xml.

Add the below markup in ClientAcccessPolicy.xml

Now you have a ClientAccesspolicy.xml file in the WCF project.

Listing 4: ClientAccesspolicy.xml

Now open the WCF Service project in windows explorer. To do this right click on the project and select open folder in Window explorer.

Copy clientaccesspolicy.xml file and paste it in C:\inetpub\wwwroot. Make sure the clientaccesspolicy.xml file exists in the wwwroot folder.

Consuming the service in Silverlight 4.0

Create a Silverlight project by clicking on Project->new ->Silverlight -> Silverlight Application.

And create a web site to host the Silverlight application.

Now design the page in XAML.

Listing 5: MainPage.xaml

Explanation of the XAML clode:

• Divided the main grid in two rows.
• In first row put a textbox to display the result.
• In second row put a stack panel with horizontal orientation.
• Put a canvas inside stack panel
• Put two text box and button in canvas.

Now right click on the Silverlight project and add a Service Reference.

Give the URL of the WCF service hosted in IIS in Address text box. And then click GO.

Calling the Service

Add the namespace:

On the click event of the button, add the following code:

Explanation of the previous code:

• Silverlight calls WCF service asynchronously
• So the first completed event is getting called. If the operation contract name is GetMessage then the event name will be GetMessageCompleted.
• After event aysnc function is being called.

Listing 6: MainPage.Xaml.cs

Conclusion

In this article we saw how we can consume a WCF Service in a Silverlight application with cross domain. I hope this article was useful. Thanks for reading and happy coding.

About Dhananjay Kumar

Dhananjay Kumar is a developer who blogs at http://debugmode.net/. He is Microsoft MVP ,Telerik MVP and Mindcracker MVP. You can follow him on twitter @debug_mode This author has published 8 articles on DotNetSlackers. View other articles or the complete profile here.