Click here to Skip to main content
Click here to Skip to main content

How To Load A Class Into a New Appdomain, and Use It: Quick and Simple

, 1 Sep 2006 CPOL
Rate this:
Please Sign up or sign in to vote.
Appdomain loading

Introduction

This is a quick smash-and-grab type article. Download the code and you'll see how to load a class into a secondary appdomain and use it.

One of the things I miss most about VB6, is the ability to load an object into a separate process, detached from my current process, so if something goes wrong in that object, my main process does not hang (application isolation). In the VB6 world, we create an out of process activex EXE. The .NET way requires us to use Appdomains.

My first read on appdomains left me confused and asking myself "why is this so hard? All I want to do is create an out of process object and use it." After reading Wrox's book "Visual Basic.NET Reflection Handbook", the lights went on and I better understood how these types of things work.

I'm not an expert in this area, but this code will save you some time researching how to create an 'out of process' object the .NET way...

First, you create the app domain:

' Create the app domain
otherDomain = System.AppDomain.CreateDomain("DuffBeerIsGreatDomain")

Next, you create the object:

' Do it the easy way, but you have to pay attention to case in the object.classname

Dim herHello As echo.Hello = _
    CType(otherDomain.CreateInstanceAndUnwrap("echo", "echo.Hello"), echo.Hello)

Now, invoke a method on the object:

MessageBox.Show(herHello.echo("As createinstanceandunwrap"))

It is *that* simple. Now obviously, there are pitfalls, one of them being that in the above createinstanceandunwrap call, the echo.Hello parameter is case sensitive..

The sample code contains example calls which avoid this issue.

Enjoy!

History

  • 1st September, 2006: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

Random Coding Monkey
Web Developer
United States United States
No Biography provided

Comments and Discussions

 
-- There are no messages in this forum --
| Advertise | Privacy | Terms of Use | Mobile
Web02 | 2.8.150129.1 | Last Updated 1 Sep 2006
Article Copyright 2006 by Random Coding Monkey
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid