Message exchanging between two or many independent objects

Question

Hi all what is the best practice for message exchanging between two or many independent objects in the same application domain? For example i have two classes ClassA and ClassB they don't know about another. But the object of ClassA must react on action or event in object of ClassB. Thanks in advance

Vadim · Answer

Thank you. That is exact what i search

Vulpes · Answer

If you don't want A and B to have references to each other then here's how you could implement a simple message exchange scheme between them using a third 'singleton' class C as a conduit. The code can easily be generalized to 3 or more objects: using System; enum MessageType { Post Reply } class C { private static C c; public static C GetInstance() { if(c == null) c = new C(); return c; } private C() { } public Action SendMessage; public void OnSendMessage(string sender string[] recipients string message MessageType type) { if (SendMessage != null) { SendMessage(sender recipients message type); } } } class A { public A() { C.GetInstance().SendMessage += ReceiveMessage; } private void ReceiveMessage(string sender string[] recipients string message MessageType type) { if (Array.IndexOf(recipients A) > - 1) { Console.WriteLine(The message : '{0}' received from {1} message sender); if (type == MessageType.Post) { SendMessage(A new string[]{sender} Thanks for your message MessageType.Reply); } } } public void SendMessage(string sender string[] recipients string message MessageType type) { C.GetInstance().OnSendMessage(sender recipients message type); } } class B { public B() { C.GetInstance().SendMessage += ReceiveMessage; } private void ReceiveMessage(string sender string[] recipients string message MessageType type) { if (Array.IndexOf(recipients B) > - 1) { Console.WriteLine(The message : '{0}' received from {1} message sender); if (type == MessageType.Post) { SendMessage(B new string[]{sender} Thanks for your message MessageType.Reply); } } } public void SendMessage(string sender string[] recipients string message MessageType type) { C.GetInstance().OnSendMessage(sender recipients message type); } } class Program { static void Main() { A a = new A(); B b = new B(); b.SendMessage(B new string[]{A} Hello MessageType.Post); Console.ReadKey(); } } The output is: The message : 'Hello' received from B The message : 'Thanks for your message' received from A