Bidirectional communication in Distributed Objects in cocoa - objective-c

Question

I am new to Cocoa programming...I am learning IPC with Distributed Objects.
I have made a simple example where I am vending objects from the server and calling them in the client.I am successful in passing messages from client object to the server But I want to pass messages from server to client[Bidirectional]...How do I do that?
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
MYMessageServer *server = [[MYMessageServer alloc] init];
NSConnection *defaultConnection=[NSConnection defaultConnection];
[defaultConnection setRootObject:server];
if ([defaultConnection registerName:#"server"] == NO)
{
NSLog(#"Error registering server");
}
else
NSLog(#"Connected");
[[NSRunLoop currentRunLoop] configureAsServer];
}
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
// Insert code here to initialize your application
//Getting an Vended Object
server = [NSConnection rootProxyForConnectionWithRegisteredName:#"server" host:nil];
if(nil == server)
{
NSLog(#"Error: Failed to connect to server.");
}
else
{
//setProtocolForProxy is a method of NSDistantObject
[server setProtocolForProxy:#protocol(MYMessageServerProtocol)];
[server addMessageClient:self];
[server broadcastMessageString:[NSString stringWithFormat:#"Connected: %# %d\n",
[[NSProcessInfo processInfo] processName],
[[NSProcessInfo processInfo] processIdentifier]]];
}
}
- (void)appendMessageString:(NSString *)aString
{
NSRange appendRange = NSMakeRange([[_messageView string] length], 0);
// Append text and scroll if neccessary
[_messageView replaceCharactersInRange:appendRange withString:aString];
[_messageView scrollRangeToVisible:appendRange];
}
- (void)addMessageClient:(id)aClient
{
if(nil == _myListOfClients)
{
_myListOfClients = [[NSMutableArray alloc] init];
}
[_myListOfClients addObject:aClient];
NSLog(#"Added client");
}
- (BOOL)removeMessageClient:(id)aClient
{
[_myListOfClients removeObject:aClient];
NSLog(#"Removed client");
return YES;
}
- (void)broadcastMessageString:(NSString *)aString
{
NSLog(#"Msg is %#",aString);
self.logStatement = aString;
[_myListOfClients makeObjectsPerformSelector:#selector(appendMessageString:)
withObject:aString];
}
#protocol MYMessageServerProtocol
- (void)addMessageClient:(id)aClient;
- (BOOL)removeMessageClient:(id)aClient;
- (void)broadcastMessageString:(NSString *)aString;

Answer 1

You haven't shown the code for MYMessageServer or MYMessageServerProtocol, specifically the -addMessageClient: method. However, once you have passed the server a reference to an object in the client, the server can message that object like normal and that message will be sent over D.O. to the client.
So, the client is sending self (its application delegate) to the server via -addMessageClient:. The server can simply call methods on the object it receives in its implementation of -addMessageClient: and that will call methods on the client's application delegate object. The server can keep that reference somewhere, such as an array of clients in an instance variable, and continue to message the client at later times, too, if it wants. The server will want to clear that reference out when the connection closes, which it can detect from notifications that NSConnection posts.