July 13, 2010

Testing COM components

Here's some code you can use to try to load your Type through COM.
You can use the GetPEKind method to get the platform that the assembly was compiled for.

(Recently ran into a problem where I couldn't be sure the assembly I'd registered was registered correctly, my query was particular to win64, there are some changes in the registry entries for 64bit windows when running 32 bit applications.)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Reflection;

namespace ComTest

class MyGetTypeFromCLSIDSample
public static void Main()
Guid myGuid1 = new Guid("3A21CE6B-8571-4955-9780-BAE1EE3215C0");//my Types GUID, regasm was ran on this assembly.

// Get the type associated with the CLSID
// and specify whether to throw an exception if an error occurs
// while loading the type.

//if this shows The type of the GUID is System.__ComObject.
//The current module is mscorlib.dll.
//assembly kind ILOnly, PE32Plus , platform AMD64
//then your assembly isn't registered.

Type myType1 = Type.GetTypeFromCLSID(myGuid1, true);
Console.WriteLine("The GUID associated with myType1 is {0}.", myType1.GUID);
Console.WriteLine("The type of the GUID is {0}.", myType1.ToString());

// Show the current module.
Module m = myType1.Module;
Console.WriteLine("The current module is {0}.", m.Name);

PortableExecutableKinds peKind;
ImageFileMachine machine;
m.GetPEKind(out peKind, out machine);

Console.WriteLine("assembly kind {0} , platform {1}", peKind.ToString(), machine);//assembly kind ILOnly , platform I386


July 09, 2010

Visual Studio build configuration with x64 "Any CPU"

In Visual Studio you may have noticed, and ignored, the pulldowns in your toolbar which usually contain "Release" "Any Cpu".
The "Any CPU" part in particular is of interest especially if you plan on running your apps on Windows 64.
These configurations are contained in each project and solution i.e. if you open the projects in a text editor you'll see sections in the XML which contain the settings. These settings are also accessible through the Visual Studio UI via the pulldowns mentioned earlier.

The significance of the "Any CPU" is it's telling the compiler to compile the code into assemblies into code which can run on either 32 or 64 bit machines. If your assemblies are used by an application written in 64bit (and of course the app runs on a 64bit machine) then your assemblies will be used in the 64bit context, the same stands for 32bit (of course 32bit apps can also run on 32 or 43 bit machines).
64bit machines have an additional registry section "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node", this section contains registry entries for applications build with "Any CPU" or x86 (32bit). The normal registry section "HKEY_LOCAL_MACHINE\SOFTWARE" is used for pure 64bit apps but if the 64bit OS comes across 32bit apps then it uses the "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node" to get registry settings.
Note to that your installer may target this "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node" section if your assemblies and installer are configured to "Any CPU" or "x86". It may not be what you expect.

There are some cavaets around the Registry entries used on 64bit machines. If your application uses registry entries in any way then you'll need to be aware.
When you compile your assemblies with "Any CPU" and your assembly is used by an application written for 64bit then the registry entries used will be slightly different.
(thanks to Miral on the msdn forums)
  • .NET app compiled for "x86":
    • Always 32-bit
    • On 32-bit platforms, accesses 32-bit registry
    • On 64-bit platforms, accesses 32-bit registry (inside Wow6432Node)
      • 64-bit registry inaccessible (without doing something weird)
  • .NET app compiled for "x64":
    • Always 64 bit
    • On 32-bit platforms, won't run
    • On 64-bit platforms, accesses 64-bit registry (not inside Wow6432Node)
      • If you want to get to the 32-bit registry, you need to do something weird
  • .NET app compiled for "AnyCpu"
    • Either 32 or 64 bit depending on platform
    • On 32-bit platforms, accesses 32-bit registry
    • On 64-bit platforms, accesses 64-bit registry (not inside Wow6432Node)
      • If you want to get to the 32-bit registry, you need to do something weird

July 07, 2010

Roles in ASP.NET

Roles are part of the Authorization in ASPNET i.e. a mechanism to tell if the user has or has not access to resources.

Roles are a mechanism to group users into sets of permissions.
Roles can reuse already existing groups from windows. Roles can also be linked into a SQL database.
Roles are configured on the aspnet websites web.config.


XMLSerializer and .NET CLR (sgen.exe)

You might have spotted on your .NET projects in Visual Studio a radiobutton to turn on/off serialization "Generate serialization assembly" in your project's property's Build tab , so what's that all about?

Serialization is a mechanism for recreating .NET objects from text. There's another post in this blog on the topic. So why is this option on your project? in brief it's there as a performance improvement for .NET CLR.

.NET serializes the assemblies when loading, if you tick the "Generate serialization assembly" listbox your creating a second assembly to accompany the original, the second assembly , with extension .xmlserialize.dll , will be loaded by the CLR at load load if it exists, this improves performance at load time because now the CLR does not have to serialize the original assembly at load time instead if can just load the already existing second assembly.

The second assembly is generated with Visual Studio with a tool called sgen.exe.