C# .NET - Application Domain

Application Domain

An Application Domain is a light-weight process.  It is a logical and physical unit of isolation built around every .NET application by the Common Language Runtime (CLR) and contains its own set of code, data and configuration settings.  Multiple application domains can exist simultaneously in the same process.  The default application domain is created when the Common Language Runtime is first loaded into a process.  From then on, the CLR loads an assembly implicitly into an Application Domain the first time it encounters and references a type in the MSIL code. Assemblies can also be created explicitly loaded in Application Domains.  This article discusses what Application Domains are and the differences between Application Domains and Processes.  It also discusses Default Domains and how Application Domains can be created, loaded and unloaded explicitly.

Creating Application Domain

Check this out. just a little HelloWorld application to create an AppDomain in C#.

This is for a console application :

using System;
using System.Reflection;
using System.Runtime.Remoting;

public class ShowAppDomain : MarshalByRefObject
{
 public string GetAppDomainName()
 {
 return AppDomain.CurrentDomain.FriendlyName; // gets the Current application domain thread and returns it's nameAppDomain name
 }
}

public class CallMyHelloWorld
{
public static void Main ()
{
AppDomain ad = AppDomain.CreateDomain ("Yupee! My AppDomain!"); // create a new domain
ShowAppDomain ad2 = (ShowAppDomain) ad.CreateInstanceAndUnwrap(Assembly.GetCallingAssembly().GetName().Name,"ShowAppDomain");

/*
We use the AppDomain.CreateInstanceAndUnwrap method to Create a new instance of a specified type.
Assembly.GetCallingAssembly().GetName().Name returns The Assembly object and the name of the method that calls the presently executing method.
*/

Console.WriteLine("Here's my own AppDomain " + ad2.GetAppDomainName()); // Voila!
}
}

If you want one AppDomain to talk to another, then you should go for .net remoting, check the below article for moreinfo,

.NET Remoting and Cross Domain Marshalling

http://69.10.233.10/KB/IP/CrossDomainRemoting.aspx

Creating an Application Domain

"System.AppDomain" is the main class you can use to deal with application domains. To create an application domain use one of the overloaded "CreateDomain" methods in this class.

The following piece of code creates an application domain and assign a name to it.

        Dim NDomain As AppDomain

        NDomain = AppDomain.CreateDomain("Domain1")

The above code declare an "NDomain" variable of type "AppDomain", then calls the "CreateDomain" method giving it a string that represents the name of the newly created application domain.

You can configure the newly created application domain by using the "AppDomainSetup" class with its most important property "ApplicationBase" which defines the root directory for this application domain. You can also use this class to control many settings for the newly created application domain like application name, cache path, configuration file, license file, and others.

You can use this class as shown in the following code.

        Dim NDomainInfo As New AppDomainSetup

        NDomainInfo.ApplicationBase = "C:\AppDomains\Ex2"

        Dim NDomain As AppDomain

        NDomain = AppDomain.CreateDomain("Domain1", Nothing, NDomainInfo)

        MsgBox(NDomain.BaseDirectory())

Check thius out, it very good article:

http://www.beansoftware.com/NET-Tutorials/Application-Domain.aspx