From: "mail@..." <mail@...>
Date: 2008-11-08T00:48:02+09:00
Subject: Re: Unix Sockets SOCK_DGRAM

On Nov 7, 9:32 am, David Rodriguez
<david.francisco.rodrig...@gmail.com> wrote:
> Hi
>
> THis is my first post so I hope I do not break any rule with it.
>
> I did not found how to send packets via a datagram UNIX sockets? I was
> able to create a server using:
>   sock = Socket::new( Socket::AF_UNIX, Socket::SOCK_DGRAM, 0 )
>   sock.bind(Socket.pack_sockaddr_un($path))
>   for i in 1..10
>     p sock.recvfrom(124)
>   end
>
> But I need the client to send packets. I can not change from SOCK_DGRAM
> to SOCK_STREAM as it would be sufficient to use UNIXServer and
> UNIXSocket.
>
> So how can I do it?
>
> David
> --
> Posted viahttp://www.ruby-forum.com/.

I am not sure if this will help or not.  In the example code below the
"user" process sends a datagram message to the "alarm manager" and the
"parameter store" processes.  The "user" process then receives an ack
back.


#Simple simulation using domain datagram sockets.   Everything is
started off when the user
#sets a parameter.
#
#Note that ruby does not provide specific support for domain datagram
sockets and we must use the "c" like
#basic_socket and socket classes directly (socket inherits from
basic_socket).
#
#Note that recvfrom blocks until a message is received.


require 'socket'
USER_SOCKET = "user.sock"
PARAM_STORE_SOCKET = "param_store.sock"
ALARM_MGR_SOCKET = "alarm_mgr.sock"

system("rm #{USER_SOCKET}")
system("rm #{PARAM_STORE_SOCKET}")
system("rm #{ALARM_MGR_SOCKET}")

fork {# The User.
    dgram_socket = Socket::new(Socket::AF_UNIX, Socket::SOCK_DGRAM, 0)
    dgram_socket.bind(Socket.pack_sockaddr_un(USER_SOCKET))#Without
this the receiver does not know who we are when using recvfrom.

    sleep(5);#Don't do anything until system is up.

    dgram_socket.send("x = 4", 0,
Socket.pack_sockaddr_un(PARAM_STORE_SOCKET))
    dgram_socket.send("x = 4", 0,
Socket.pack_sockaddr_un(ALARM_MGR_SOCKET))

    while(1)
        msg = dgram_socket.recvfrom(26)
        print "User: #{msg[0]} from #{msg[1]}\n"
    end

}

fork {# The Parameter Store.
    dgram_socket = Socket::new(Socket::AF_UNIX, Socket::SOCK_DGRAM, 0)
 
dgram_socket.bind(Socket.pack_sockaddr_un(PARAM_STORE_SOCKET))#Without
this the receiver does not know who we are when using recvfrom.

    sleep(5);#Don't do anything until system is up.

    while(1)
        msg = dgram_socket.recvfrom(26)
        print "Parameter Store: #{msg[0]} from #{msg[1]}\n"
        dgram_socket.send("ACK " + msg[0], 0,
Socket.pack_sockaddr_un(USER_SOCKET))
    end

}

fork {# The Alarm Manager.
    dgram_socket = Socket::new(Socket::AF_UNIX, Socket::SOCK_DGRAM, 0)
 
dgram_socket.bind(Socket.pack_sockaddr_un(ALARM_MGR_SOCKET))#Without
this the receiver does not know who we are when using recvfrom.

    sleep(5);#Don't do anything until system is up.

    while(1)
        msg = dgram_socket.recvfrom(26)
        print "Alarm Mgr: #{msg[0]} from #{msg[1]}\n"
        dgram_socket.send("ACK " + msg[0], 0,
Socket.pack_sockaddr_un(USER_SOCKET))
    end

}


Process.wait#Without this have to start using kill to get rid of the
processes created with fork.


Mark