How can I persist data between 2 appliaiton

Areeb Quazi

Hi,

I have 3 application

1- C# window application1
2- C# window application2
3- Class library
I am Passing data from application 1 to class library and I want this data from application 2. But I am not getting

For ex My class library have one class

public class1
{
public bool Flag = false;
public void hello(bool f)
{

Flag = f;
}
}

application 1

class1 cs = new class1();
cs.hello(true);

but from application 2 I am always getting Flag value false event I passed true
Please suggest how can i persist value of flag.

Thanks

5 Replies

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Vulpes13y ago
Do you have the attribute applied to your Main() method?

If you don't, then I'd add it because otherwise the default threading model for COM interop is MTA.

If you already have the attribute, are you explicitly starting any threads in your application?

If you are, then try calling this method before starting the thread:

' t is the new thread object
t.SetApartmentState(ApartmentState.STA)
0
Areeb Quazi13y ago
Thanks for your reply, I really appreciate you help.

My problem is I migrated vb6 activeX application into .net and exposed it as ActiveX exe. Which takes data from java web application and pass it to vb.net application. Now i used Remoting now I am able to pass data from Java --> vb.net (ActiveX) --> to vb.net windows application
but when I am trying to assign this value to any text box then I am getting error
An error occurred creating the form. See Exception.InnerException for details. The error is: ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment.
and not able to rasise any event of
0
Vulpes13y ago
In that case, you really need to use inter-process communication (remoting or WCF) to share the object between different processes.

Notice that even though it's the same dll, it's loaded into different Application Domains and so even if you made the Flag field static, each Application Domain would still have its own independent copy and changes made by one application would not be persisted to the other.

However, if you don't mind making class1 into a singleton and are not too bothered about performance, then you can simply save the Flag field to a disk file each time you change it.

// library

using System.IO;

public class class1
{
static class1 instance = null;
static string path = "class1.txt";

public static class1 GetInstance()
{
if(instance == null)
{
instance = new class1();
}

if(!File.Exists(path)) instance.Flag = false; // default value

return instance;
}

class1(){} // private constructor

public bool Flag
{
get
{
return bool.Parse(File.ReadAllText(path));
}

set
{
File.WriteAllText(path, value.ToString());
}
}

public void hello(bool f)
{
Flag = f;
}
}

// application 1

using System;

class Test
{
static void Main()
{
class1 c1 = class1.GetInstance();
Console.WriteLine(c1.Flag);
c1.hello(true);
Console.ReadKey();
}
}

// application 2

using System;

class Test
{
static void Main()
{
class1 c1 = class1.GetInstance();
Console.WriteLine(c1.Flag);
Console.ReadKey();
}
}

If you start application 1 and then (from a different console window but from the same directory) you start application 2, then the former should print "false" and the latter "true" to the console.

Notice that not only will the Flag value be persisted between applications but between different runnings of those applications unless you do something to delete the text file between sessions.

0
Areeb Quazi13y ago
They are running at same time
0
Vulpes13y ago
Are applications 1 and 2 running at different times or concurrently?

If they're running at different times, then one way of doing it would be for application 1 to serialize the class1 object to disk just before it exits and for application 2 to then deserialize the object when it starts up.

Clearly, for this to work, both applications would have to work with a file which has a pre-agreed name and is stored in a pre-agreed location.
0