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Friday, August 21. 2009

Using a Businessobject in Silverlight from client and server

Following situation:
I have a BusinessObject called Person which i want to use in a Silverlight project. This Buisnessobject should be returned from a WCF service and should have some functionality on it. Now, if i define this object on the WCF service, i can use it only as DTO, but i cannot add additional functionality on it(Or at least i am unable to use it in a silverlight application).

Now, i'm showing a way how you can get all this requirements done.

1. Create a new silverlight project

Just create a Silverlight 3.0 project.

Im using the visual studio built in webserver for providing the xap file as well as for the WCF service.

2. Create the business object and the wcf service

Now, just add a Silverlight enabled webservice to the web project.

In this newly added service1.cs, i add a new method GetPerson and a new class Person which will be my Businessobject/Datatransverobject for this sample. I have put the Person class into the same file.

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service1
{
[OperationContract]
public Person GetPerson()
{
return new Person() {FirstName = "manuel", LastName = "kaderli", Salutation = "Dear Mr. "};

}
}

[DataContract]
public class Person
{
[DataMember]
public string FirstName { get; set; }
[DataMember]
public string LastName { get; set; }
[DataMember]
public string Salutation{ get; set; }
}

This service is ready to use, and i now add a service reference on the silverlight project.

3. Use the service from silverlight

On the xaml page, i add a button and some TextBlocks. I'm using the Binding mechanism for get/set data to the controls.

The csharp file does only call the service, and bind the person object to the LayoutRoot.

public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
}

private void btnGetPerson_Click(object sender, RoutedEventArgs e)
{
Service1Client sc = new Service1Client();
sc.GetPersonCompleted += new EventHandler<GetPersonCompletedEventArgs>(sc_GetPersonCompleted);
sc.GetPersonAsync();
}

void sc_GetPersonCompleted(object sender, GetPersonCompletedEventArgs e)
{
Person person = e.Result;
LayoutRoot.DataContext = person;
}
}

When i now run this application, and after pressing the button it shows me the values of the three properties which are bound to the xaml.

4. Addin functionality to the person BusinessObject

I want to add a new control to the page, which should display the full letter salutation, in my sample this would be "Dear Mr. Kaderli Manuel". Of course i could do this right on the silverlight page. But this functionality belongs to the BusinessObject. Since the person object is sent via wcf, there is no possibility of code sharing. And i don't want to edit any generated proxy files.
What i now want to is to share the person BusinessObject between the web/wcf server and the silverlight application. But because they don't use the same .net framework(web/wcf uses .net 3.5 and the silverlight application obviously the silverlight framework) which are incompatible.

First i add a new project of type Silverlight Class Library to my solution.

Then i move the Person class which is in the .svc service file into a seperate class in the newly created class library project. Now i can add the method GetLetterSalutatioin to this class.
Make sure to include System.Runtime.Serialization with the using statement.

using System.Runtime.Serialization;

namespace BusinessDTO
{
[DataContract]
public class Person
{
[DataMember]
public string FirstName { get; set; }
[DataMember]
public string LastName { get; set; }
[DataMember]
public string Salutation { get; set; }

public string LetterSalutation
{
get
{
return string.Format("{0} {1} {2}", Salutation, LastName, FirstName);
}
}

public void DoSomethiing()
{
//add any other businesslogic here
}
}
}

Since i have remove this code from the web/wcf project there are now some errors, because tihs class is missing. I just add this Person class as link.
Just select add existing item, select the Person class from the silverlight class library project, and make sure to use add as link.

In the .svc file, i just have to add the new namespace:

using BusinessDTO;

In the silverlight project, it's even easier. Just add the BusinessObject project as a project reference.
Make sure to renew the service reverence on the silverlight application, in order to get the latest proxy. I had first to delete the existing service reference, and the to add it again to get it working.

Now, i'm able to write the following in the silverlight client:

BusinessDTO.Person person = e.Result;
string letterSalutatioin = person.LetterSalutation;
person.DoSomethiing();

Now i have clientside a object wihch comes from a wcf service but which also can have business functionality.
It is also possible to use the new property LetterSalutation as source for a control.

5. Use specific functionality client or serverside

Because i use the code from a silverlight class library now in a silverlight project as well as in a .net 3.5 project, there may be some problems.
E.g. some functionality like ObservableCollection are not in the same assmbly in the .net 3.5 framework and in the silverlight framework. Then you might have situations where you like to have code for either client or serverside.
For this you can use #if SILVERLIGHT statement in the BusinessObjects classes.

#if SILVERLIGHT
//code available only for silverlight applicatioins
#else
//code available for web/wcf service
#endif

You can get the whole solution right here.

Now, this is the way i'm working with BusinessObjects and silverlight/wcf. If one has a remark, or an other solution, please leave a commen.

cheers

Posted by suntsu in Silverlight, WCF, work at 16:03 | Comments (0) | Trackbacks (0)

Defined tags for this entry: silverlight, wcf

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:

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>

<extensions>
<behaviorExtensions>
<add name="myFault" type="SilverlightWCF.Web.MyFaultBehavior, SilverlightWCF.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</behaviorExtensions>
</extensions>

...

<behaviors>

<endpointBehaviors>
<behavior name="myFaultBehavior">
<myFault/>
</behavior>
</endpointBehaviors>

...


<endpoint address="" binding="customBinding" bindingConfiguration="customBinding0"
contract="SilverlightWCF.Web.MyCoolService" behaviorConfiguration="myFaultBehavior" />

...


<serviceDebug includeExceptionDetailInFaults="true" />

Third: Create an operation contract which throws an exception.
Make sure not to throw regular exception, but FaultException

[OperationContract]
public void ThrowException()
{
throw new FaultException("this is my Exception");
}

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

Posted by suntsu in Silverlight, WCF, work at 23:11 | Comments (2) | Trackbacks (0)

Defined tags for this entry: Silverlight, WCF

Tuesday, August 5. 2008

Use WCF service from a Silverlight application

At work, i'm involved in a silverlight application, and i've got my first challange.
It's not that easy to use an WCF service which is not hosted in an IIS environment right from an Silverlight application.
With the help of the official Silverlight forum, i figured it out.
You may download an test this sample visual studio solution. Of course you have to set up the proper environment for developing Silverlight application first.
The solution contains the following project:

SilverLightTestAppWeb (Startup website for the silverlight application)
SilverLightTestApp.csproj (Silverlight application)
WCF.csproj (WCF service for providing data)
WCFServer.csproj (Console application for hosting WCFServer.csproj)
WCFPolicy.csproj (WCF/REST service for providing clientaccesspolicy.xml)
WCFPolicyServer.csproj (Console application for hosting WCFPolicy.csproj)
WCFTestApp.csproj (Test application for WCFServer.csproj)

To test it, the following projects must be started: WCFServer, WCFPolicyServer, SilverLightTestAppWeb.
With this you are ready to go. If you then see the silverlight application, and press the button, it will first call the WCFServer, and then request the WCFPolicyServer for receive the clientaccesspolicy.xml. The policy is only checked once at the first webservice call.
For testing it, you may download it from here WCF.rar.
Just make sure to set the proper startup projects: