Hi all!
I got a c++ non-blocking server socket, with all the clients stored in a std::map structure.
I can call the send() method for each clientObject to send something to the connected client and that works pretty good already.
But for sending a message to all (broadcast?) i wanna know: there is something better than do a for/loop with all the clients and call to ClientObject->send("foo") each iteration?
Or should i just try having a peek on multicast sockets?
Thanks in advance. Rag.
Multicast would be much preferable... as long as you are talking about local nodes i.e. within the "broadcast/multicast" domain on the LAN.
Of course there are multicast distribution protocols for wider dispersion of such messages but they are seldom used and, depending on your specific case, you could/couldn't reliability depend on such facility.
The use of Multicast translates to lots of savings from a sender point of view: only one send operation needs to occur instead of n*send.
Multicast is only an option if you're communicating over a LAN. It won't work over the Internet.
What you may want to do here is to demultiplex the sockets using asynchronous I/O. This allows you to send data to multiple sockets at the same time, and use asynchronous event handlers to deal with each transmission.
I would recommend looking into Boost ASIO for a portable way to do this. You can also use OS specific system calls, (such as poll/select on UNIX or epoll on Linux) to do this, but it is a lot more complicated.
You'd better off to do udp unicast to each host unless you have those very expensive switches. Yes, broadcast/multicast can actually be slower for most switches that have much wimpier CPU than your pcs. Doing anything other than simple forwarding would slow them down tremendously.
Do a benchmark to find out.