Thursday, March 26, 2009

TCP server in Erlang

Came across this good article on writing a TCP server in Erlang. Author forgot to mention one thing here.

connect(Listen) ->
{ok, Socket} = gen_tcp:accept(Listen),
inet:setopts(Socket, ?TCP_OPTS),
% kick off another process to handle connections concurrently
spawn(fun() -> connect(Listen) end),

In the above code snipper (from the above mentioned blog), it is to be noted that after getting the connection via gen_tcp:accept/1, a process is spawned to continue listen on the socket and the client is served from the same process unlike in any other language where a thread is spawned to serve the incoming client request and main thread continue to listen on the socket. This is very important to note as the incoming client socket has a ownership relationship with the process. If you spawn a process to serve the client, it won't work as the messages won't be delivered to the new process instead are delivered to the process in which gen_tcp:accept/1 was executed.

No comments:

Book Promotion