Jimmy Rasmussens Blog : .NET

Code Contracts

jimmytr — Sat, 25 Apr 2009 23:00:00 GMT

pre-conditions, post-conditions, object invariants in .NET - go here

Share sourcecode between Silverlight and WPF Applications

jimmytr — Wed, 11 Jun 2008 23:49:30 GMT

Sharing code between Silverlight and WPF Applications has been a returning wish from several of the customers in our Microsoft Innovation Center in Denmark. The base class libraries are very similar, but obviously something is missing in the 3-4 MB Silverlight download you just installed on that iMac in your girlfriends officespace... therefore if you use features in .NET that is not supported by the SL BCL sharing is not possible. As you are compiling your projects to a given runtime the binary sharing is not really an option either. That leaves us with source code sharing - which is close to 100% better than no sharing at all.

Code to share typically include Presentation Models, Controllers, Domain Objects, Data Transfer Objects etc.

It is a good idea to start with the lowest denominator (Silverlight) if you have the choice from the beginning of your project. Some limitations may require you to think completely differently than you would normally if you were starting out with the full featureset of WPF (ex. ICommand) - you will eventually run into grayzones and I will leave it up to your judgement to decide when and how much you can/should share.

One way to achieve code file sharing is to use the "Add As Link" in the "Add Existing Item" dialog in Visual Studio (push the little arrow to get to it)

An example is shown below:

Notice the "link" icon on the "MyClass.cs" file in the Silverlight project.

If you have code that is not really shared but nice to keep in the shared file you can make use of the C# preprocessor directives. That sounds like a bad thing to do, but you may have to use different namespaces etc. Silverlight projects actually has a SILVERLIGHT "define" allowing you to include specific code simply by writing:

#if SILVERLIGHT
using System.Windows.Media.Animation;
#endif

You will notice that this is grayed out in the FullCLR project (and obviously the directive #if !SILVERLIGHT may be used in the opposite case)

I have just learned about another way of sharing source files that is less visible in the UI (no "linked icon") but seem to solve the exact same problem.

Any comments and other ideas are welcome - i acknowledge that it is kind of simple but it solves most cases where source code sharing is possible.

Security tips and code clips [german]

jimmytr — Sat, 23 Jun 2007 11:41:00 GMT

ThinkTecture's Dominick Baier has helped MSDN in Germany to create a number of clips and How-To's covering several aspects of security on the .NET platform.

If you remember any german from school I would recommend you point your browser this way

Smart Clients from Greece?

jimmytr — Tue, 05 Jun 2007 10:20:00 GMT

Microsoft Code Name "Acropolis" has finally been released to the public as a technology preview.

Having played with some internal releases it has become clear to me what a huge amount of work the team has put into this technology. I would like to congratulate with this important milestone and will obviously help getting customer feedback.

Features included in Acropolis CTP1 includes:

- Declarative Composition - allows you to declarative program the structure of application components

- Navigation support - manages activation and deactivation of components

- Document Life Time support - manages the life time of a document bject

- Layout Pane - Split style and tab style UI layout that leverages WPF

- Transition Animation - Prepackage transitions built on WPF

... and all these comes with Application Design Time Support!

Go get your copy here and please provide feedback to our hard-working team in Redmond.

Note: The CTP1 requires the Visual Studio Codename "Orcas" to run - get it here

ISB - Biztalk Services in the sky

jimmytr — Thu, 26 Apr 2007 17:58:00 GMT

If you haven't done so already I recommend you take a look at our latest Biztalk Services CTP from the Connected Systems Division (http://connectedsystems.spaces.live.com/).

Quite a few people has already commented on this and I will just forward you to some of the links I have found interesting:

http://labs.biztalk.net/

http://blogs.msdn.com/stevemar/

http://blogs.msdn.com/clemensv/archive/2007/04/25/internet-service-bus.aspx

http://www.dennispi.com/

Have Fun!

Writing Test Code with Impersonation

jimmytr — Sat, 14 Apr 2007 22:01:00 GMT

Some of your (unit) tests may be required to run with predefined credentials, and if all your tests should run as one single identity your might as well use the command line runas.exe tool to start your testrunner (or whatever your favorite naming for this is). In some (rare?) occasions you may need to do tests with a large number of different credentials. There is a number of ways to do this and here I will show you two methods: P/Invoke and Windows Communication Foundation (WCF). I don’t feel like explaining a lot today so I’ll just drop you some sample code you can play with.

P/Invoke

using System;

using System.Security.Principal;

using System.Runtime.InteropServices;

using System.Threading;

namespace Test

{

class Program

{

static void Main(string[] args)

{

User u = new User("joe",string.Empty,"P\"ssw0rd");

Thread t = new Thread(DoWorkAs);

t.Start(u);

Console.ReadLine();

}

private static void DoWorkAs(object o)

{

User u = o as User;

//Print user of application

Console.WriteLine(WindowsIdentity.GetCurrent().Name);

IntPtr hToken = IntPtr.Zero;

IntPtr hTokenDuplicate = IntPtr.Zero;

if (Win32.LogonUser(u.UserName, u.Domain, u.Password, 2 /*LOGON32_LOGON_INTERACTIVE*/, 0 /*LOGON32_PROVIDER_DEFAULT*/, out hToken))

{

if (Win32.DuplicateToken(hToken, 2, out hTokenDuplicate))

{

WindowsIdentity windowsIdentity = new WindowsIdentity(hTokenDuplicate);

WindowsImpersonationContext impersonationContext = windowsIdentity.Impersonate();

// domain\username

Console.WriteLine(WindowsIdentity.GetCurrent().Name);

//INVOKE UNIT TEST HERE - or call test controller or whatever you prefer to call it today...

//revert

impersonationContext.Undo();

Console.WriteLine(WindowsIdentity.GetCurrent().Name);

}

if (hToken != IntPtr.Zero) Win32.CloseHandle(hToken);

if (hTokenDuplicate != IntPtr.Zero) Win32.CloseHandle(hTokenDuplicate);

}

public class User

{

public User(string u, string d, string p)

{

Domain = d;

UserName = u;

Password = p;

}

public string UserName;

public string Domain;

public string Password;

}

public class Win32

{

// P/Invoke snask

[DllImport("advapi32.dll", SetLastError = true)]

public static extern bool LogonUser(

string lpszUsername,

string lpszDomain,

string lpszPassword,

int dwLogonType,

int dwLogonProvider,

out IntPtr phToken);

[DllImport("advapi32.dll", SetLastError = true)]

public extern static bool DuplicateToken(IntPtr ExistingTokenHandle, int

SECURITY_IMPERSONATION_LEVEL, out IntPtr DuplicateTokenHandle);

[DllImport("kernel32.dll", SetLastError = true)]

public static extern bool CloseHandle(IntPtr hHandle);

}

(Note: In this example I could have used the System.Net.NetworkCredential class instead of the homemade User class)

WCF

using System;

using System.ServiceModel;

using System.Security.Principal;

using System.Threading;

using System.Net;

namespace TestWCF

{

[ServiceContract(Namespace = "NotDefault")]

public interface IImpersonateTest

{

[OperationContract]

void RunAsTest();

}

public class ImpersonateTest : IImpersonateTest

{

[OperationBehavior(Impersonation = ImpersonationOption.Allowed)]

public void RunAsTest()

{

Console.WriteLine(

string.Format("Inside a WCF Service - caller: {0}",

WindowsIdentity.GetCurrent().Name));

//INVOKE UNIT TEST HERE - or call test controller or whatever you prefer to call it today...

}

class Program

{

static string _address = "net.pipe://localhost/ImpersonateTest";

static NetNamedPipeBinding _binding = new NetNamedPipeBinding();

static void Main(string[] args)

{

Thread t = new Thread(Server);

ManualResetEvent mre = new ManualResetEvent(false);

t.Start(mre);

mre.WaitOne();

EndpointAddress epa = new EndpointAddress(_address);

ChannelFactory<IImpersonateTest> factory = new ChannelFactory<IImpersonateTest>(_binding,_address);

factory.Credentials.Windows.ClientCredential = new NetworkCredential("joe", "P\"ssw0rd", String.Empty);

IImpersonateTest proxy = factory.CreateChannel();

proxy.RunAsTest();

((ICommunicationObject)proxy).Close();

Console.WriteLine("Press <ENTER> to exit.");

Console.ReadLine();

t.Abort();

t.Join();

Console.WriteLine("Done...");

}

static void Server(object o)

{

ManualResetEvent mre = o as ManualResetEvent;

ServiceHost sh = new ServiceHost(typeof(ImpersonateTest));

try

{

sh.AddServiceEndpoint(typeof(IImpersonateTest), _binding, _address);

sh.Authorization.ImpersonateCallerForAllOperations = true;

sh.Open();

mre.Set(); //Ready - client can continue

Console.WriteLine("Service host opened");

Thread.Sleep(System.Threading.Timeout.Infinite);

}

catch (ThreadAbortException)

{

//Abort is called at some point.

}

finally

{

sh.Close();

Console.WriteLine("Service host closed");

}

EntLib 3.0 Released

jimmytr — Sun, 08 Apr 2007 10:27:00 GMT

The P&P team has finished the third major release of the enterprise library. See Tom's post for more information. Try the new WCF integration with logging, exception handling and validation application blocks. Download from MSDN.

XmlSerialization snippet

jimmytr — Sat, 24 Mar 2007 17:39:00 GMT

I keep writing this code - now I can find it on my blog in the future :-)

public static class StringXmlSerializer

{

public static string Serialize<T>(T obj)

{

XmlSerializer s = new XmlSerializer(typeof(T));

StringBuilder sb = new StringBuilder();

StringWriter sw = new StringWriter(sb);

s.Serialize(sw, obj);

return sb.ToString();

}

public static T Deserialize<T>(string str)

{

XmlSerializer s = new XmlSerializer(typeof(T));

StringReader sr = new StringReader(str);

return (T)s.Deserialize(sr);

}

Externalize your Communication Protocol Details with WCF

jimmytr — Mon, 19 Mar 2007 11:31:00 GMT

In general the Web Service client proxy generated by “Add Web Reference” in Visual Studio is all you need to start talking to a Web Service. Some of you may need to present a certificate to the remote server you are calling and for this purpose you would typically populate the ClientCertificates collection on the generated proxy class like:

WebServiceProxy prx = new WebServiceProxy();

X509Certificate certificate = FetchRelevantCertificate();

prx.ClientCertificates.Add(certificate);

prx.SomeMethod();

The fictitious method FetchRelevantCertificate finds the relevant certificate using the X509Store class or a similar wrapper. While this is probably what many of us have done in the past it adds an unfortunate coupling to the communication protocol in your compiled code.

As you probably know WCF allow you to configure almost anything relevant for the communication externally to the code in the System.ServiceModel configuration section. The equivalent code using a WCF generated (svcutil.exe) client proxy would be:

WebServiceProxy prx = new WebServiceProxy();

prx.SomeMethod();

Nothing here specifies the need of a client certificate for the communication. For the code to actually present the required certificate you should simply add the following (or similar) section to your app.config (or web.config):

<system.serviceModel>

<clientCertificate

findValue="MyCertificate"

storeLocation="CurrentUser"

storeName="My"

x509FindType="FindBySubjectName" />

</clientCredentials>

</behavior>

</endpointBehaviors>

</behaviors>

</security>

</binding>

</basicHttpBinding>

</bindings>

<endpoint address="https://demoappserver.mydomain.local/SSLTest/Service.asmx"

binding="basicHttpBinding"

bindingConfiguration="ClientSecureBinding"

behaviorConfiguration="ClientSecureBehavior"

contract="MyContractHere">

</endpoint>

</client>

</system.serviceModel>

As you see this gives you complete isolation of business code and communication protocol related code. I agree that you could build a similar externalization for the wsdl.exe generated proxy classes, but with WCF this is really plain vanilla. As a side note you obviously do not have to change anything on the server side to start using WCF clients. In short: svcutil.exe is your friend ;-)

Nothing new really - I just got excited about this point late last week.