This is what I want to do:

I want to dynamically load a class from an extenal assembly into my application. (using Silverlight 2.0 and Visual Studio 2008).

The class which I want to load is called MyAssembly.MyClass; It is derived from Canvas; It resides in an assembly called MyAssembly.dll. I amually deployed the DLL in the ClientBin directory of my Web-Project.

Her is what have tried:

I have tried to load the assembly using Assembly.Load("MyAssembly"). It failed with File not found. (Are there any good working examples for 'Assembly.Load()'?).

Now I am trying to solve the problem with AssemblyPart.Load(...). I am able to load the assembly, but nw I am not able to create instances of objects within that assembly. Can you help?

Here is the code I am working on:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Reflection;
using System.Net;
using System.IO;

namespace POC_Reflection_Dynamic_Load
{
   public partial class Page : Canvas
   {
      TextBlock txt;
      WebClient downloader;

      public Page()
      {
         // Initialize Debug Test Area
         txt = new TextBlock();
         txt.Text = "";
         txt.FontSize = 12;
         txt.Foreground = new SolidColorBrush(Color.FromArgb(255, 255, 0, 200));
         this.Children.Add(txt);

         // Download the DLL using a WebClient?
        downloader = new WebClient();
        downloader.OpenReadCompleted += new OpenReadCompletedEventHandler(onOpenReadCompleted);
        downloader.OpenReadAsync(new Uri("MyAssembly.dll", UriKind.Relative));
        debug("Downloader Base Address = " + downloader.BaseAddress.ToString());
      }

      private void onOpenReadCompleted(object o, OpenReadCompletedEventArgs args)
      {
         loadAssembly(args.Result);
      }

      private void loadAssembly(Stream s)
      {
          Assembly a;

          try
          {
               AssemblyPart ap = new AssemblyPart();
               ap.Load(s);
               debug("Assembly Part successfully loaded: " + ap.Source);

               // Here is the problem. Loading the Assembly (DLL) into the AssemblyPart was successful.
               // But how do I create an instance of a class which is defined in that DLL? Here is an
               // attempt do do that.
               //(IT DOES NOT WORK !!!)
               Canvas can = (Canvas)Assembly.GetExecutingAssembly().CreateInstance("MyAssembly.MyClass");
               if (can == null)
               {
                     debug("can is null!!!!!!!!!");
                     return;
               }

              debug("Canvas successfully created");
              this.Children.Add(can);

             debug("Canvas successfully added");
          }
          catch (Exception ex)  
          {
             debug("Exception when loading the assembly part:");
             debug(ex.ToString());
          }
      }

      public void debug(String s)
      {
         txt.Text += "\n" + s;
      }
   }
}

I found the solution. I hope this helps other people....

When loading the DLL as a Stream into the AssemblyPart, you can create an Assembly at the same time:

          AssemblyPart ap = new AssemblyPart();
          Assembly a = ap.Load(s);

The Assembly will then allow you to create an object:

          Canvas can = (Canvas)a.CreateInstance("MyAssembly.MyClass");

Here is the entire method loadAssembly(). All other parts of the source code (above) remain unchanged.
 

private void loadAssembly(Stream s)
{
     try
     {
          AssemblyPart ap = new AssemblyPart();
          Assembly a = ap.Load(s);
          Canvas can = (Canvas)a.CreateInstance("MyAssembly.MyClass");
          if (can == null)
          {
                 debug("can is null!!!!!!!!!");
                 return;
          }

          this.Children.Add(can);
          debug("Canvas successfully added");
     }
     catch (Exception ex)
     {
          debug("Exception when loading the assembly part:");
          debug(ex.ToString());
     }
}

Thank you for this. Your code works great. I made an adaption using my resizable window control. I placed it here:

SilverlightDesktop.net

With source code of course and even a credit for you.

http://ADefwebserver.com

Well, thanks for your comment. And thanks for putting it up. It is always good to know that someone finds this usefull