Design pattern for handling multiple message types

Question

I\'ve got the GOF sitting on my desk here and I know there must be some kind of design pattern that solves the problem I\'m having, but man I can\'t figure it out.

F

Answer 1

In a similar scenario I have a server which receives lots of different messages from multiple clients.

All messages are sent serialized and start with an identifier of message type. I then have a switch statement looking at the identifier. The messages are then deserialized (to very differing objects) and processed as appropriate.

A similar thing could be done by passing objects which implement an interface which includes a way of indicating message type.

public void ProcessMessage(IMessage msg)
{
    switch(msg.GetMsgType())  // GetMsgType() is defined in IMessage
    {
        case MessageTypes.Order:
            ProcessOrder(msg as OrderMessage);  // Or some other processing of order message
            break;
        case MessageTypes.Trade:
            ProcessTrade(msg as TradeMessage); //  Or some other processing of trade message
        break;
        ...
    }
}