i am working on a chat program.
[JAVA] [Without RMI, just Sockets] [Command example: 'sentToMike', 'Disconnect', 'Login', etc]
How do i send a "command" Object through Sockets to be excecuted on the server directly? I want to send all kind of messages(Strings, Audio, Video), and all kind of Command objects to many clients, any of them. I know there exist ObjectInput/Output objects and all of that. My problem is trying to get a polymorphic solution.
For example i want to create a IMessage interface with a method signature "execute()". Then i would create a AudioMessage, TextMessage, etc that implements the IMessage. The problem is that at some point i need to share the server code with the client and viceversa in order Server and client know all the objects involved in every excecute method. And worst of all is that if i send an IMessage, the server would't know what specific type the message is, so i dont know to what kind cast the Object. The same would happen when i send the Command back to the client.
I can work a solution with simple text strings "commands" and a big and ugly switch in the server(and in the client by the way), but i believe that is not elegant, i would need to create a wrapper class with the string command plus the object of the kind i want to send plus the string with the type of object been sent(Message[String type; String command; IMessage->AudioMessage ]), this wont be polymorphic since i will need to use the switch to ask the type of the object and then cast it to AudioMessage for example. Furthermore i would need to share a lot of code between server and client and i dont know if that would be ok.
Any advice will be very very welcome, maybe i need a design pattern, an architecture pattern, i have no clue.
There are security reason to not allow just any code to run on server!
But if you are willing to expose your server (and client) to unknown code, then you need to also serve classes bytecode, and have classloaders to enable instanciating classes' types you expect the other end to accept. Your protocol would have to send the full classname and locations (if not inlining the bytecode) of the alien class (and all its dependencies not found in parent classloader), for the purpose of hoping to call any method of such object.
(FYI, that just reinventing RMI).
If you don't have to call anything on this object (it's not your case, I know, but I musy say it), then it is passive and there is really no point in transporting it as an object instance.