1. Introduction
2. The Interfaces & First Plugin
3. The Host Application
4. Wrapping Up

Comments

1. haneen ahmad
   27 Sep 2009 at 00:23

   hi

   when i run the host i found this error : Warning 1 Could not resolve this reference. Could not locate the assembly "Interfaces". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors. Plugin 1

   "PluginSample.Interfaces.IPlugin" is not defined

   can u help me to splve this problem

   thanks

2. aroni san
   03 Jun 2008 at 00:13

   Just add event handlers to the menu items before returning from InitializeMenu, e.g.

   [quote]menu1.Click += new EventHandler (nameOfCallbackFunction);[/quote]

3. JazzyXun
   22 Aug 2007 at 15:02
   Hi There,
   
   I found a very easy way to add controls to the host.
   
   

   Public Function InitializeMenu() As System.Windows.Forms.ToolStrip Implements Interfaces.IPlugin.InitializeMenu
           Dim Menu As New ToolStrip
           Dim menu1 As New ToolStripMenuItem("Plugin")
           menu1.DropDown = CreateCheckImageContextMenuStrip("Calculate")
           Menu.Items.Add(menu1)
           Menu.Dock = DockStyle.Top
           Return Menu
    End Function
   
   
   
   
   
   
   
   
   
   
   

   The interface should have this:    
   

   Function InitializeMenu() As ToolStrip
   
   
   
   

   Now you are able to add an control to the host like this:
   Me.ToolStripContainer1.TopToolStripPanel.Controls.Add(objPlugin.InitializeMenu)
   
   The only thing i did not figure out yet is how to handle when you click on the control.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
4. Jon Frost
   19 Jun 2007 at 08:23
   I liked this article, all seven times that I read it. But I felt that it lacked a bit of security. I came across this article on msdn. It shows quite nicely how to wrap untrusted code in a sort of security blanket.
5. novy
   15 Apr 2007 at 11:20

   I rewrote your application in C# and everthing works except one thing.

   After loading  assembly and creating plugin instance I am casting plugin instance to plugin interface and I get excepion "Specified cast is not valid"

   I have no idea what is wrong.

6. Christian Rygg
   16 Oct 2006 at 13:35
   This artice was just what I was looking for - however it turned out to lead me to the conclusion that the feature I wanted wasn't achievable by .Net - at least not without some dirty coding... You code describes plugging in, but not plugging out. To my shock I realized that .Net doesn't allow unloading of assemblies!
   
   I needed the plug in functionality to swap and update plug-ins on a regular basis, for an ASP.Net application. However, it seems I must shut down the site completely to replace an existing plug-in with a new version...
7. borvik
   09 Dec 2005 at 17:11

   Great article!
   

   
   This will come in very handy with an application I have in mind .
   

   
   Just a note about using this in VB2005 (I'm using Express edition right now, hopefully I'll upgrade):
   

   
   The CreateInstance method of the PluginServices works fine, and does return an instance of the class that can be used but only when put into an Object type.
   

   
   You don't have the full list of functions and subroutines available to you using the object.
   

   
   When using the DirectCast, to cast the instance to an variable declared as the Interface - it doesn't like that cast and throws an exception.
   

   
   To fix this do what Prozac mentiond - change the references of [Assembly].LoadFrom() to [Assembly].LoadFile() and it works fine.
   

   
   Thanks for the great article!

8. alchol100
   30 Nov 2005 at 01:59
   Hi Tim,
   
   I think your article is great, i'm looking for it for months, and finally...
   
   I just have a question:
   
   If I want that a plugin add a button ont the host form, is it possible? can you help me please?
   
   thanks in advance,
   Ivan
9. Jimmy Kelly Jr
   17 Jun 2005 at 15:31

   The complete code is available in the source code, however I'll post it for you anyway.
   

   
   

   Code:

   
      Public Structure AvailablePlugin
          Public AssemblyPath As String
          Public ClassName As String
      End Structure
   

   
   

   
   Enjoy!

10. Jimmy Kelly Jr
    17 Jun 2005 at 15:30

    I noticed that when I used [Assembly].LoadFrom(), it kept on loading the first plugin that was initially loaded,
    to fix this; use [Assembly].LoadFile() insted.
    

    
    DotNet Framework 1.1, Visual Studio 2003, Visual Basic.NET.

11. Ralph Mallamace
    30 Sep 2004 at 23:42

    I can't get AvailablePlugin to work. VB.NET reports that
    "Type 'AvailablePlugin' is not defined." Has anyone else had this problem?

12. malloc
    27 Apr 2004 at 11:51

    Hi.
    

    
    I've been trying to find the way of doing an application with pluggable components over vb6, but have not found any help. I read the subject of this article and was very excited but when I realized it was about .net I got frustrated. Could you please explain me how it is possible to make a plugin-based app in vb6.
    Thanx
    

    
    

    ---

    
    malloc

13. Developer Fusion Bot
    01 Jan 1999 at 00:00

    This thread is for discussions of Writing Plugin-Based Applications.