You had me at "Hello World!" : Web Service

Silverlight: How to Make Your WCF Web Service Work for All Users

nikola — Mon, 09 Jun 2008 00:26:00 GMT

Specification of the Problem

A WCF web service works when a user types site in his browser with www in the name:

· http://www.nokola.com/SampleService/ServiceClientAppTestPage.aspx Works OK!,

but it stops working if the same site is typed without www:

· http://nokola.com/SampleService/ServiceClientAppTestPage.aspx Fails with error message:

“The remote server returned an unexpected response: 404 Not Found”

Note: the samples in this article are using Silverlight 2 Beta 2.

Why is This Happening?

WCF Web services work currently with one base Uri only. Some website hosts (if not most) pass 2, 3 or more base Uri-s to a web service when they activate it.

For example for the above web service the based addresses passed during activation may look like this:

http://www.nokola.com/SampleService/ServiceClientAppTestPage.aspx

http://nokola.com/SampleService/ServiceClientAppTestPage.aspx

http://something.something.nokola.com/SampleService/ServiceClientAppTestPage.aspx

If we don’t do anything special to filter the base addresses, our web service creation will fail. If I remember correctly, the error message looks like this:

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

Parameter name: item

To work around this issue, I create a custom ServiceHostFactory and return only one base address:

public class MyServiceHostFactory : ServiceHostFactory {

protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) {

return new CustomServiceHost(serviceType, new Uri("http://www.nokola.com/SampleService/ServiceClientAppTestPage.aspx "));

}

public class CustomServiceHost : ServiceHost {

public CustomServiceHost(Type serviceType, params Uri[] baseAddresses)

: base(serviceType, baseAddresses) { }

protected override void ApplyConfiguration() {

base.ApplyConfiguration();

}

Because we can return only one address, our service is usable only from this address. That’s why when I type http://nokola.com/SampleService/ServiceClientAppTestPage.aspx I got the above error message.

One Way to Fix It

I’ve posted the not working code of the WCF Service here: http://www.nokola.com/sources/ServiceClientApp.zip

Let’s fix it!

The fix that I will apply is to create a second .svc file and create a custom factory for the non-www address in it. Then I’ll programmatically call one service or the other from within the Silverlight Client App, based on what address the user typed in their browser.

Step 1: Create ServiceNoWww.svc

Copy-paste in Solution Explorer Service.svc and rename it to ServiceNoWww.svc

Change its factory specification to:

Factory="MyServiceHostFactoryNoWww"

Step 2: Create custom factory for the ServiceNoWww.svc in code behind

Open App_Code/Service.cs and add (don’t change the existing one) this text:

public class MyServiceHostFactoryNoWww : ServiceHostFactory {

protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) {

return new CustomServiceHost(serviceType, new Uri("http://nokola.com/SampleService/Service.svc"));

}

Note that I removed the www. before nokola.com and named the class same using the same name specified in ServiceNoWww.svc

Step 3: Change the client app to switch between the two services transparently

Replace the service instantiation code in Page.xaml.cs.

Original:

client = new ServiceClientApp.ServiceReference1.ServiceClient();

Changed:

Binding defaultBinding = new System.ServiceModel.BasicHttpBinding();

EndpointAddress defaultAddress;

if (HtmlPage.Document.DocumentUri.AbsoluteUri.ToLower().Contains("www."))

{

defaultAddress = new System.ServiceModel.EndpointAddress("http://www.nokola.com/SampleService/Service.svc");

}

else

{

defaultAddress = new System.ServiceModel.EndpointAddress("http://nokola.com/SampleService/Service.svc");

}

client = new ServiceClientApp.ServiceReference1.ServiceClient(defaultBinding, defaultAddress);

}

client = new ServiceClientApp.ServiceReference1.ServiceClient(defaultBinding, defaultAddress);

Note: you don’t have to add reference to the second service in your app, only change the default address using the above code.

Silverlight 2 Beta 1 Links to SDK Help, Reference and Samples

nikola — Mon, 17 Mar 2008 02:31:00 GMT

Here are some interesting Silvelright 2 Beta 1 documentation links:

High-level portal to the Managed Reference: http://msdn2.microsoft.com/en-us/library/bb404716.aspx
Controls: http://msdn2.microsoft.com/en-us/library/cc189031(vs.95).aspx
Control Templates and Styles: http://msdn2.microsoft.com/en-us/library/cc278068(vs.95).aspx
Web Services: http://msdn2.microsoft.com/en-us/library/cc296254(VS.95).aspx

I'm posting this because I need to go to these links almost every day and it is easier to remember in the blog. Hopefully it will help someone else also to discover this data easier.

Calling Web Services and Accessing UI from Timer Event in Silverlight

nikola — Thu, 13 Mar 2008 23:50:00 GMT

If you try accessing UI from a timer event, you'll Exception: Invalid cross-thread access. This happens because the timer code is running on different thread and trying to access controls on the main thread. Here's how to fix it:

Edit: thanks to jackbond on the Silverlight.NET forum http://silverlight.net/forums/p/11533/36916.aspx#36916 who pointed me in the right direction.

The preferred way to do this is by using DispatcherTimer:

DispatcherTimer timer = new DispatcherTimer();

timer.Interval = new TimeSpan(1000);

timer.Tick += new EventHandler(timer_Tick);

timer.Start();

Before I was using this method, which still works but is not as good in this case (harder to read):

Action _onTimerAction = new Action(OnTimer);

Timer _timer = new Timer(new TimerCallback(delegate(object action)

{ Dispatcher.BeginInvoke(_onTimerAction); }), null, 0, 3000);

private void OnTimer()

{

// call web service/update UI here

}

Also, I learned that Dispatcher.BeginInvoke is very usable for calling functions on the UI thread from another thread, as in the above sample.

Visual Studio 2008 Walkthrough: Creating, Hosting and Using WCF Services with Silverlight 2

nikola — Wed, 12 Mar 2008 13:57:00 GMT

Before we Start

The final project is a sample that sends a string to WCF web service from Silverlight and gets a response back.

Sample source code: http://blogs.msdn.com/nikola/attachment/8168735.ashx (Edit: see comments on how to change the source to work for localhost instead of public web site)

Edit: updated test link: http://www.nokola.com/SampleService/ServiceClientAppTestPage.aspx

This walkthrough is provided as-is, no warranties or rights.

Issues that this post will help you address

This post will help you with deployment, hosting and these 3 kind of common issues in particular:

1. The below error may appear when trying to host the web service on the internet.

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

Parameter name: item

2. Some 500. internal server errors like HTTP Error 500.19 - Internal Server Error. This can happen when you have several web.config files in nested directories (e.g. deploying service in nested folders on the web server)

3. UnexpectedHttpResponseCode: With this walkthrough you will not see some of the cross-domain errors that I encountered, like UnexpectedHttpResponseCode. This exception is thrown at the Silverlght client side and can happen either because of cross-domain issues or because the service is throwing exceptions when accessed. If the service works fine, then try adding crossdomain.xml file to the root of your web site, as described here: http://msdn2.microsoft.com/en-us/library/cc197955(VS.95).aspx. Note that two different port numbers on the same server count as two different domains. So you might be getting this error message in case the webservice runs on localhost:12340 and the site is at localhost:12345, for example during debugging.

Creating The Projects

Prerequisites:

· VS 2008

· Silverlight SDK: http://www.microsoft.com/downloads/details.aspx?FamilyId=4E03409A-77F3-413F-B108-1243C243C4FE&displaylang=en

Creating the Silverlight project

1. Open Visual Studio 2008

2. Click File, New Project. Select C# (or VB)

3. Click Silverlight and select Silverlight Application, name it ServiceClientApp. I also check Create Directory for Solution. Click OK.

4. Select Generate and HTML test page to host Silverlight within this project. Click OK.

5. Open Page.xaml, and add a text box for typing, a button and a textblock to display the result.

Your page.xaml should look something like this:

<UserControl x:Class="ServiceClientApp.Page"

xmlns="http://schemas.microsoft.com/client/2007"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Width="400" Height="300">

</StackPanel>

</UserControl>

6. In the code-behind file, add the even handler for the button:

public partial class Page : UserControl

{

public Page()

{

InitializeComponent();

}

private void btnSend_Click(object sender, RoutedEventArgs e)

{

}

Creating the service project

1. Right-click on the solution in solution explorer and select Add -> New Web Site

2. Select WCF Service and C# (or VB) for language

3. Name the website HelloWorldService

4. In the App_code folder change in IService.cs and Service.cs the GetData function to accept string instead of int:

public string GetData(string value)

5. Add a custom service host factory to Service.cs. We add this since WCF supports one base address only and some web servers return more. If we don’t add this, you may get the following exception when trying to access the web service:

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

Parameter name: item

Below is how my Service.cs ended up after adding a custom service host and factory. I decided to host the service here: http://www.nokola.com/SampleService/Service.svc

using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.Serialization;

using System.ServiceModel;

using System.Text;

using System.ServiceModel.Activation;

// NOTE: If you change the class name "Service" here, you must also update the reference to "Service" in Web.config and in the associated .svc file.

public class Service : IService

{

public string GetData(string value)

{

return string.Format("You entered: {0}", value);

}

public CompositeType GetDataUsingDataContract(CompositeType composite)

{

if (composite.BoolValue)

{

composite.StringValue += "Suffix";

}

return composite;

}

public class MyServiceHostFactory : ServiceHostFactory

{

protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)

{

return new CustomServiceHost(serviceType, new Uri("http://nokola.com/SampleService/Service.svc"));

}

public class CustomServiceHost : ServiceHost

{

public CustomServiceHost(Type serviceType, params Uri[] baseAddresses)

: base(serviceType, baseAddresses) { }

protected override void ApplyConfiguration()

{

base.ApplyConfiguration();

}

6. In Service.svc make use of the factory:

<%@ ServiceHost Language="C#" Debug="true" Service="Service" Factory="MyServiceHostFactory" CodeBehind="~/App_Code/Service.cs" %>

7. In web.config update the wsHttpBinding to basicHttpBinding:

Deploying and Hosting

Deploying the Service

1. Right-click on the HelloWorldService web site project, and select Publish Web Site

2. Select the settings for your web site and click OK. Make sure to publish to the same address as in MyServiceHostFactory that you created. In my case I published at http://nokola.com/SampleService

3. From your web site administration tools select the SampleService fodler to be an application, otherwise you might get something like this:

Server Error in '/' Application.

Configuration Error

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS.

4. Test the service by opening it in IE. In my case I tested by opening http://nokola.com/SampleService/Service.svc

If you see a page starting like this, then Congratulations! You’ve created your service successfully:

Service Service

You have created a service.

You probably noted that the title says “Service Service”, this is not because the system is very happy with your new creation (who knows) but also because your service is named “Service”.

Deploying the Silverlight Application

Before deploying the application we have to make some more updates so it can access the service correctly:

1. Right-click on the HelloWorldService web site in Solution Explorer and select Add Silverlight Link

2. Select ServiceClientApp (should be already selected), make sure that Add test page that references this control is checked and click Add

3. Build and re-publish the service. Test it again.

4. Try opening the web page from the web site. In my case it’s at http://nokola.com/SampleService/ServiceClientAppTestPage.html

You should see your Silverlight application at that point, and the button does nothing yet

5. Go back to Visual Studio and right-click the ServiceClientApp project in the Solution Explorer. Select Add Service Reference.

6. In the Address box type the address of your service. In my case I typed http://nokola.com/SampleService/Service.svc

7. Update the Page.xaml.cs to call the service. Here’s how I updated mine:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

namespace ServiceClientApp

{

public partial class Page : UserControl

{

ServiceReference1.ServiceClient client;

public Page()

{

InitializeComponent();

client = new ServiceClientApp.ServiceReference1.ServiceClient();

client.GetDataCompleted += new EventHandler<ServiceClientApp.ServiceReference1.GetDataCompletedEventArgs>(client_GetDataCompleted);

}

private void btnSend_Click(object sender, RoutedEventArgs e)

{

client.GetDataAsync(boxTypeText.Text);

}

void client_GetDataCompleted(object sender, ServiceClientApp.ServiceReference1.GetDataCompletedEventArgs e)

{

if (e.Error != null)

{

textResponse.Text = e.Error.Message;

}

else

{

textResponse.Text = e.Result;

}

8. Rebuild and re-deploy the HelloWorldService web site.

Go to your test html (in my case http://nokola.com/SampleService/ServiceClientAppTestPage.html ), type “test” in the box and click Send to WCF web service.

If everything works OK you should see “You entered: test” below the button.

Congratulations!

Feedback is always welcome! If you enjoyed this walkthrough and want to see more like this please let me know or leave a comment.

Nikola

Configuring IIS 7 to work with WCF Web Services for Silverlight 2

nikola — Fri, 07 Mar 2008 00:18:00 GMT

I've tried these, and there are some interesting parts that can take some time figuring out by digging in docs.

This post will probably solve the 404.3 error (svc not registered as MIME type)

So here's the whole solution for getting a WCF service started up and using it from Silverlight 2 Beta 1:

1. To build the service: How to: Build a Service for Silverlight Clients
2. To enable cross-domain for the service, if needed: How to: Make a Service Available Across Domain Boundaries

3. To add the service to IIS 7:

Create new IIS 7 application - Right-click on Default Web Site in the IIS Manager console, Add application, setup the folder (e.g. D:\test\SampleAppFolder) and name. Click OK
Deploy your service to http://localhost/SampleApp (or your app virtual name)
Important This step took me a while to figure out: install WCF: open admin cmd prompt, and execute ServiceModelreg -i in c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation folder.

c:\>cd c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation

c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation>

c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation>ServiceModelreg -i
Microsoft(R) Windows Communication Foundation Installation Utility
[Microsoft (R) Windows (R) Communication Foundation, Version 3.0.4506.648]
Copyright (c) Microsoft Corporation. All rights reserved.

Installing: Machine.config Section Groups and Handlers

Installing: System.Web Build Provider

Installing: System.Web Compilation Assemblies

Installing: HTTP Handlers

Installing: HTTP Modules

Installing: ListenerAdapter node for protocol net.tcp

Installing: Protocol node for protocol net.tcp

Installing: TransportConfiguration node for protocol net.tcp

Installing: ListenerAdapter node for protocol net.pipe

Installing: Protocol node for protocol net.pipe

Installing: TransportConfiguration node for protocol net.pipe

Installing: ListenerAdapter node for protocol net.msmq

Installing: Protocol node for protocol net.msmq

Installing: TransportConfiguration node for protocol net.msmq

Installing: ListenerAdapter node for protocol msmq.formatname

Installing: Protocol node for protocol msmq.formatname

Installing: TransportConfiguration node for protocol msmq.formatname

Installing: HTTP Modules (WAS)

Installing: HTTP Handlers (WAS)

c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation>

Hope this helps. If you have any other suggestions or things you stumbled upon please let me know. I appreciate your feedback!