Executing Code in Another Application Domain (C# Programming Guide)
Once an assembly has been loaded into an application domain, the code it contains can be executed. The simplest way to do this is to use AssemblyLoad which will load the assembly into the current application domain, and begin running the code at the assembly's default entry point.
If you want to load the assembly into another application domain, use ExecuteAssembly or ExecuteAssemblyByName, or one of the other overloaded versions of these methods.
If you want to execute the other assembly starting other than at the default entry point, define a new type in the remote assembly, deriving from MarshalByRefObject. Then use CreateInstance to create an instance of that type in your application.
Consider the following file, which creates an assembly consisting of a single namespace and two classes. Assume this assembly has been built, and is stored on drive C with the name HelloWorldRemote.exe.
// This namespace contains code to be called.
namespace HelloWorldRemote
{
public class RemoteObject : System.MarshalByRefObject
{
public RemoteObject()
{
System.Console.WriteLine("Hello, World! (RemoteObject Constructor)");
}
}
class Program
{
static void Main()
{
System.Console.WriteLine("Hello, World! (Main method)");
}
}
}
To access the code from another application, you can either load the assembly into the current application domain or create a new application domain and load the assembly into it. If you load the assembly into the current application domain with Assembly.LoadFrom, you can use Assembly.CreateInstance to instantiate an instance of the RemoteObject class, which causes the object constructor to be executed.
Note
For information about the disadvantages of using Assembly.LoadFrom, see the "Remarks" section of Assembly.LoadFrom(String).
static void Main()
{
// Load the assembly into the current appdomain:
System.Reflection.Assembly newAssembly = System.Reflection.Assembly.LoadFrom(@"c:\HelloWorldRemote.exe");
// Instantiate RemoteObject:
newAssembly.CreateInstance("HelloWorldRemote.RemoteObject");
}
When loading the assembly into a separate application domain, use AppDomain.ExecuteAssembly to access the default entry point or AppDomain.CreateInstance to create an instance of the RemoteObject class. Creating the instance causes the constructor to be executed.
static void Main()
{
System.AppDomain NewAppDomain = System.AppDomain.CreateDomain("NewApplicationDomain");
// Load the assembly and call the default entry point:
NewAppDomain.ExecuteAssembly(@"c:\HelloWorldRemote.exe");
// Create an instance of RemoteObject:
NewAppDomain.CreateInstanceFrom(@"c:\HelloWorldRemote.exe", "HelloWorldRemote.RemoteObject");
}
If you do not want to load the assembly programmatically, use Add Reference from the Solution Explorer to specify the assembly HelloWorldRemote.exe. Then, add a using HelloWorldRemote; directive to the using block of your application, and use the RemoteObject type in your program to declare an instance of the RemoteObject object, like this:
static void Main()
{
// This code creates an instance of RemoteObject, assuming HelloWorldRemote has been added as a reference:
HelloWorldRemote.RemoteObject o = new HelloWorldRemote.RemoteObject();
}
See Also
Concepts
Application Domains and Assemblies
Programming with Application Domains
Reference
Application Domains (C# Programming Guide)