Wednesday, July 22. 2009
Silverlight/WCF starter solution (not for dummies)
It took me several days to create a proper solution fundament for silverlight, so i decided to publish my starter solution. Maybe it helps some of you.
There is a solution available for download for each of the four parts.
I had the following requirements:
Let's start. I'm going to implement each of this topic separately, and hopefully get a solution working till this blog entry is finish.
Initialize solution
I just start with a new Silverlight solution in visual studio 2008. The only thing i change from original, is to assign a static port to the built in web server. This makes the life with wcf much easier.
Then add a new Silverlight-enabled WCF Service to the web project, create some operation contract, and add a service reference to the silverlight project.
For this, there are two possibilities:
1. Do it yourself (Write something like a session agent service)
2. Use the ASP session management
I guess there are lots of reasons not to use aspNetCompatibility (The most obvious might be performance), but the simplicity of it was the reason for me to choose it anyway. I have to say that i did not invent this, i just copied it from an article of SpoonStomper from the silverlight forum.
The following goal i want to achieve. I press a button on my silverlight application which sends a string to my service. Then i want to press another button and get back this string again(Sounds really easy btw.).
To enable the asp session management you first have to edit the web.config
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
//this should be default since silverlight 3
On your service class, you have to change the RequirementsMode from Allowed to Required
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
public class MyCoolService{.
With this modification, you're ready to go. Now you can use the HttpContext.Current.Session for handling session stuff.
[OperationContract]
public void ServiceCallOne(string message)
{
HttpContext.Current.Session["Test"] = message;
}
[OperationContract]
public string ServiceCallTwo()
{
return (string)HttpContext.Current.Session["Test"];
}
You can download the solution with activated asp session management from here
Make sure to use my .suo file, since the service settings are stored in this file.
The user impersonation is build on top of the previous topic. Since we are asp.net controlled, we can use the HttpContext to impersonate.
Here you can find the description from microsoft
[OperationContract]
public string WhoAmIAfterImpersonate()
{
((WindowsIdentity)HttpContext.Current.User.Identity).Impersonate();
return HttpContext.Current.User.Identity.Name;
}
After the Impersonate, the service stuff will be executed as the user who has called it.
Btw. as far as i understand, this requires ntlm authentication. To get this in firefox without being asked for username and password, have a look here
You can download the solution with Impersonate from here
Since it is not possible to catch regular exception from a wcf service in a silverlight application, there is another way to do it.
I just explain it in a short story, and give the example. You may find the whole story from microsoft here.
First: Create a FaultBehavior class in your web project:
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
using System.Web;
namespace SilverlightWCF.Web
{
public class MyFaultBehavior : BehaviorExtensionElement, IEndpointBehavior
{
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
SilverlightFaultMessageInspector inspector = new SilverlightFaultMessageInspector();
endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
}
public class SilverlightFaultMessageInspector : IDispatchMessageInspector
{
public void BeforeSendReply(ref Message reply, object correlationState)
{
if (reply.IsFault)
{
HttpResponseMessageProperty property = new HttpResponseMessageProperty();
// Here the response code is changed to 200.
property.StatusCode = System.Net.HttpStatusCode.OK;
reply.Properties[HttpResponseMessageProperty.Name] = property;
}
}
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
// Do nothing to the incoming message.
return null;
}
}
// The following methods are stubs and not relevant.
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
}
public void Validate(ServiceEndpoint endpoint)
{
}
public override System.Type BehaviorType
{
get { return typeof(MyFaultBehavior); }
}
protected override object CreateBehavior()
{
return new MyFaultBehavior();
}
}
}
Second: Edit the web.config
<system.serviceModel>
<!--Add a behavior extension within the service model-->
<extensions>
<behaviorExtensions>
<add name="myFault" type="SilverlightWCF.Web.MyFaultBehavior, SilverlightWCF.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</behaviorExtensions>
</extensions>
...
<behaviors>
<!--Add a endpointBehavior below the behaviors-->
<endpointBehaviors>
<behavior name="myFaultBehavior">
<myFault/>
</behavior>
</endpointBehaviors>
...
<!--Set the behaviorConfiguration of the endpoint-->
<endpoint address="" binding="customBinding" bindingConfiguration="customBinding0"
contract="SilverlightWCF.Web.MyCoolService" behaviorConfiguration="myFaultBehavior" />
...
<!--For debugging, it might be cool to have some more error information.
to get this, set includeExceptionDetailInFaults to true-->
<serviceDebug includeExceptionDetailInFaults="true" />
Third: Create an operation contract which throws an exception.
Make sure not to throw regular exception, but FaultException
Fourth: Handle the error within your silverlilght application
private void btnThrowException_Click(object sender, RoutedEventArgs e)
{
serviceClient.ThrowExceptionCompleted += new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(serviceClient_ThrowExceptionCompleted);
serviceClient.ThrowExceptionAsync();
}
void serviceClient_ThrowExceptionCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
if (e.Error == null)
{
// In case of success
}
else if (e.Error is FaultException)
{
FaultException fault = e.Error as FaultException;
txtThrowException.Text = e.Error.Message;
}
}
You can download the solution with error handling from here.
Here i have to say, to unit test a single wcf method is not that difficult(its like if you unit test a library).
But if you use the asp.net session to store information, the client(browser) handles this with cookies. If you want to unit test a method which needs a value from the session, you have to handle the cookies manually. Here you can find a very good explanation for handling cookies in asmx/wcf services.
First you have to create a unit test project. I had to do this by hand, since create unit test on a method did not create a new project.
Then use Add service reference to add a reference of the web/wcf project to your unit test project.
Now implement the test methode:
[TestMethod]
public void TestMethod1()
{
string _sharedCookie = string.Empty;
//Creates connection to the WCF service
//It's done by code, not via config file
//The config file would be overwritten all the time
EndpointAddress objEndpoint = null;
CustomBinding cb = new CustomBinding();
//binding depends how your web server is set up
BinaryMessageEncodingBindingElement bmebe = new BinaryMessageEncodingBindingElement();
//TextMessageEncodingBindingElement tebe = new TextMessageEncodingBindingElement(MessageVersion.Default, Encoding.UTF8);
HttpTransportBindingElement htbe = new HttpTransportBindingElement();
cb.Elements.Add(bmebe);
cb.Elements.Add(htbe);
objEndpoint = new EndpointAddress("http://localhost:11111/MyCoolService.svc");
MyCoolServiceClient _serviceClient = new MyCoolServiceClient(cb, objEndpoint);
//howto manage cookies: http://megakemp.wordpress.com/2009/02/06/managing-shared-cookies-in-wcf/
using (new OperationContextScope(_serviceClient.InnerChannel))
{
_serviceClient.ServiceCallOne("my first message to the server");
// Extract the cookie embedded in the received web service response
// and stores it locally
HttpResponseMessageProperty response = (HttpResponseMessageProperty)
OperationContext.Current.IncomingMessageProperties[HttpResponseMessageProperty.Name];
_sharedCookie = response.Headers["Set-Cookie"];
}
using (new OperationContextScope(_serviceClient.InnerChannel))
{
//this sets the cookie for the next service request
HttpRequestMessageProperty request = new HttpRequestMessageProperty();
request.Headers["Cookie"] = _sharedCookie;
OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = request;
string returnValue = _serviceClient.ServiceCallTwo();
Assert.AreEqual("my first message to the server", returnValue);
}
}
As you can see, i call two method separately, and i return with the second method the session value which was set in the first method call.
You can download the solution with error handling from here.
Please let me know when you find mistakes/bugs in this sample.
cheers
manuel
There is a solution available for download for each of the four parts.
I had the following requirements:
- Session management.
In the second web service call, i want to know something from the first call
- Impersonate user
I don't want to enter my credentials if my service has to work as my user.
- Error handling
It's not very cool to get a white website after an error occurs.
- Unit tests of the wcf service
It would be great to have tests for the stuff above
Let's start. I'm going to implement each of this topic separately, and hopefully get a solution working till this blog entry is finish.
Initialize solution
I just start with a new Silverlight solution in visual studio 2008. The only thing i change from original, is to assign a static port to the built in web server. This makes the life with wcf much easier.
Then add a new Silverlight-enabled WCF Service to the web project, create some operation contract, and add a service reference to the silverlight project.
1. Session management (with aspNetCompatibilityEnabled)
For this, there are two possibilities:
1. Do it yourself (Write something like a session agent service)
2. Use the ASP session management
I guess there are lots of reasons not to use aspNetCompatibility (The most obvious might be performance), but the simplicity of it was the reason for me to choose it anyway. I have to say that i did not invent this, i just copied it from an article of SpoonStomper from the silverlight forum.
The following goal i want to achieve. I press a button on my silverlight application which sends a string to my service. Then i want to press another button and get back this string again(Sounds really easy btw.).
To enable the asp session management you first have to edit the web.config
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
//this should be default since silverlight 3
On your service class, you have to change the RequirementsMode from Allowed to Required
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
public class MyCoolService{.
With this modification, you're ready to go. Now you can use the HttpContext.Current.Session for handling session stuff.
[OperationContract]
public void ServiceCallOne(string message)
{
HttpContext.Current.Session["Test"] = message;
}
[OperationContract]
public string ServiceCallTwo()
{
return (string)HttpContext.Current.Session["Test"];
}
You can download the solution with activated asp session management from here
Make sure to use my .suo file, since the service settings are stored in this file.
Impersonate user
The user impersonation is build on top of the previous topic. Since we are asp.net controlled, we can use the HttpContext to impersonate.
Here you can find the description from microsoft
[OperationContract]
public string WhoAmIAfterImpersonate()
{
((WindowsIdentity)HttpContext.Current.User.Identity).Impersonate();
return HttpContext.Current.User.Identity.Name;
}
After the Impersonate, the service stuff will be executed as the user who has called it.
Btw. as far as i understand, this requires ntlm authentication. To get this in firefox without being asked for username and password, have a look here
You can download the solution with Impersonate from here
Error handling
Since it is not possible to catch regular exception from a wcf service in a silverlight application, there is another way to do it.
I just explain it in a short story, and give the example. You may find the whole story from microsoft here.
First: Create a FaultBehavior class in your web project:
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
using System.Web;
namespace SilverlightWCF.Web
{
public class MyFaultBehavior : BehaviorExtensionElement, IEndpointBehavior
{
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
SilverlightFaultMessageInspector inspector = new SilverlightFaultMessageInspector();
endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
}
public class SilverlightFaultMessageInspector : IDispatchMessageInspector
{
public void BeforeSendReply(ref Message reply, object correlationState)
{
if (reply.IsFault)
{
HttpResponseMessageProperty property = new HttpResponseMessageProperty();
// Here the response code is changed to 200.
property.StatusCode = System.Net.HttpStatusCode.OK;
reply.Properties[HttpResponseMessageProperty.Name] = property;
}
}
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
// Do nothing to the incoming message.
return null;
}
}
// The following methods are stubs and not relevant.
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
}
public void Validate(ServiceEndpoint endpoint)
{
}
public override System.Type BehaviorType
{
get { return typeof(MyFaultBehavior); }
}
protected override object CreateBehavior()
{
return new MyFaultBehavior();
}
}
}
Second: Edit the web.config
<system.serviceModel>
<!--Add a behavior extension within the service model-->
<extensions>
<behaviorExtensions>
<add name="myFault" type="SilverlightWCF.Web.MyFaultBehavior, SilverlightWCF.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</behaviorExtensions>
</extensions>
...
<behaviors>
<!--Add a endpointBehavior below the behaviors-->
<endpointBehaviors>
<behavior name="myFaultBehavior">
<myFault/>
</behavior>
</endpointBehaviors>
...
<!--Set the behaviorConfiguration of the endpoint-->
<endpoint address="" binding="customBinding" bindingConfiguration="customBinding0"
contract="SilverlightWCF.Web.MyCoolService" behaviorConfiguration="myFaultBehavior" />
...
<!--For debugging, it might be cool to have some more error information.
to get this, set includeExceptionDetailInFaults to true-->
<serviceDebug includeExceptionDetailInFaults="true" />
Third: Create an operation contract which throws an exception.
Make sure not to throw regular exception, but FaultException
Fourth: Handle the error within your silverlilght application
private void btnThrowException_Click(object sender, RoutedEventArgs e)
{
serviceClient.ThrowExceptionCompleted += new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(serviceClient_ThrowExceptionCompleted);
serviceClient.ThrowExceptionAsync();
}
void serviceClient_ThrowExceptionCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
if (e.Error == null)
{
// In case of success
}
else if (e.Error is FaultException)
{
FaultException fault = e.Error as FaultException;
txtThrowException.Text = e.Error.Message;
}
}
You can download the solution with error handling from here.
Unit test the the wcf service (using sessions)
Here i have to say, to unit test a single wcf method is not that difficult(its like if you unit test a library).
But if you use the asp.net session to store information, the client(browser) handles this with cookies. If you want to unit test a method which needs a value from the session, you have to handle the cookies manually. Here you can find a very good explanation for handling cookies in asmx/wcf services.
First you have to create a unit test project. I had to do this by hand, since create unit test on a method did not create a new project.
Then use Add service reference to add a reference of the web/wcf project to your unit test project.
Now implement the test methode:
[TestMethod]
public void TestMethod1()
{
string _sharedCookie = string.Empty;
//Creates connection to the WCF service
//It's done by code, not via config file
//The config file would be overwritten all the time
EndpointAddress objEndpoint = null;
CustomBinding cb = new CustomBinding();
//binding depends how your web server is set up
BinaryMessageEncodingBindingElement bmebe = new BinaryMessageEncodingBindingElement();
//TextMessageEncodingBindingElement tebe = new TextMessageEncodingBindingElement(MessageVersion.Default, Encoding.UTF8);
HttpTransportBindingElement htbe = new HttpTransportBindingElement();
cb.Elements.Add(bmebe);
cb.Elements.Add(htbe);
objEndpoint = new EndpointAddress("http://localhost:11111/MyCoolService.svc");
MyCoolServiceClient _serviceClient = new MyCoolServiceClient(cb, objEndpoint);
//howto manage cookies: http://megakemp.wordpress.com/2009/02/06/managing-shared-cookies-in-wcf/
using (new OperationContextScope(_serviceClient.InnerChannel))
{
_serviceClient.ServiceCallOne("my first message to the server");
// Extract the cookie embedded in the received web service response
// and stores it locally
HttpResponseMessageProperty response = (HttpResponseMessageProperty)
OperationContext.Current.IncomingMessageProperties[HttpResponseMessageProperty.Name];
_sharedCookie = response.Headers["Set-Cookie"];
}
using (new OperationContextScope(_serviceClient.InnerChannel))
{
//this sets the cookie for the next service request
HttpRequestMessageProperty request = new HttpRequestMessageProperty();
request.Headers["Cookie"] = _sharedCookie;
OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = request;
string returnValue = _serviceClient.ServiceCallTwo();
Assert.AreEqual("my first message to the server", returnValue);
}
}
As you can see, i call two method separately, and i return with the second method the session value which was set in the first method call.
You can download the solution with error handling from here.
Please let me know when you find mistakes/bugs in this sample.
cheers
manuel
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It was nice having this example demonstarted here for State Management. But Check out with multiple different session @ sametime. you will see that only one session values will be maintain across multiple session. So i think this is not a proper solution.
Thanks for your comment.
I have to check this, but i'm going away from this asp.net compatibility mode anyway. I'll create my own session manager i quess.