Inter-process communication with VB6 application

Question

I want to have my C# application communicate with VB6 application program.
The message to communicate is simple. Here is a scenario.
  VB6 APP                                            C# APP
Run C# APP         "1", "2" or "3"       
Send command  ----------------> 
     Wait                                    Do work as the command
Exit from loop    <----------------        Return code
                                                       Terminate
I implemented this with Profile(ini file) but I want to do without file writing.
Which way would be desirable?

Answer 1

If vb6 is using process.start ( or whatever the equivalent is )  to crank the c# application up then you could just use command line arguments to pass the variable in.
A simple way to pass data between processes is ms message queue.
You have a queue for each direction you want to send stuff.
You could use a mix of these.
Pass in args to the c# app then listen for messages on a queue and the c# app pushes the return code onto that queue.
https://msdn.microsoft.com/en-us/library/aa288457%28v=vs.71%29.aspx?f=255&MSPPError=-2147217396
public class CommandLine
public static void Main(string[] args)
// The Length property is used to obtain the length of the array.
// Notice that Length is a read-only property:
Console.WriteLine("Number of command line parameters = {0}",
args.Length);
for(int i = 0; i < args.Length; i++)
Console.WriteLine("Arg[{0}] = [{1}]", i, args[i]);
https://msdn.microsoft.com/en-us/library/ms711472(v=vs.85).aspx
Hope that helps.
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