How to pass a variable from one app domain to another

Question

I'd like to know, if I have a variable,for example, a string, how to pass its value to my new app domain:

static string _str;

static void Main(string[] args) {
    _str = "abc";
    AppDomain domain = AppDomain.CreateDomain("Domain666");
    domain.DoCallBack(MyNewAppDomainMethod);
    AppDomain.Unload(domain);
    Console.WriteLine("Finished");
    Console.ReadKey();
}

static void MyNewAppDomainMethod() {
    Console.WriteLine(_str); //want this to print "abc"
}

Thanks

Answer 1

Use one of the variations of AppDomain.CreateDomain that takes an AppDomainSetup argument. In the AppDomainSetup object, set the AppDomainInitializerArguments member to the string array you want passed to the new app domain.

See sample code at http://msdn.microsoft.com/en-us/library/system.appdomainsetup.appdomaininitializerarguments.aspx.

With the code in the question, the change might look like (not tested):

static voide Main(string[] args) {
    _str = "abc";

    AppDomainSetup setup = new AppDomainSetup();
    setup.AppDomainInitializer = new AppDomainInitializer(MyNewAppDomainMethod);
    setup.AppDomainInitializerArguments = new string[] { _str };

    AppDomain domain = AppDomain.CreateDomain(
        "Domain666",
        new Evidence(AppDomain.CurrentDomain.Evidence),
        setup);

    Console.WriteLine("Finished");
    Console.ReadKey();
}

static void MyNewAppDomainMethod(string[] args) {
    ...
}

Answer 2

Addressing both your first and second requirements (passing through a value and retrieving another value back), here is a quite simple solution:

static void Main(string[] args)
{
    AppDomain domain = AppDomain.CreateDomain("Domain666");
    domain.SetData("str", "abc");
    domain.DoCallBack(MyNewAppDomainMethod);
    string str = domain.GetData("str") as string;
    Debug.Assert(str == "def");
}

static void MyNewAppDomainMethod()
{
    string str = AppDomain.CurrentDomain.GetData("str") as string;
    Debug.Assert(str == "abc");
    AppDomain.CurrentDomain.SetData("str", "def");
}

Answer 3

I know that this is an old thread but perhaps this will help other people who are researching the subject.

In this article, the writer suggests using application domain SetData and GetData methods for basic exchange of data objects that support marshal-by-value or marshal-by-reference object.