megaphone_sender

Previously...

• I made some plans about how to create megaphone_tcp.
• Determine if segment contains a complete header
• If not, then keep reading until you do have a complete header
• Parse out the connection ID and packet length, 
• If you have a complete header, then determine if you have a complete megaphone packet
• If not, then keep reading until you have a complete megaphone packet
• Send the megaphone process the completed packet.
• Wait for another packet to arrive.
• I created the part that receives headers.
• I finished the receiver

As it turned out, sending the packet off to the megaphone process was very simple.  Here is the code:


give_packet_to_megaphone (ConnectionID, Packet) ->
    megaphone ! { ConnectionID, Packet }.

Perhaps I need to work on the name a bit, but the function is ready.  At least for testing.

Emboldened by this, I went on and started writing the part of the system that sends packets to ECM.  In a burst of creativity I named this "megaphone_sender."  The startup for this module doesn't do much, just starts up a new process and then registers the PID as "megaphone_sender."  Here is the startup:

start(Socket, Config) ->

    State = #megaphone_state{socket = Socket, config = Config},

    Pid = spawn(megaphone_sender, main_loop, [State]),

    register(megaphone_send, Pid).

The main loop basically just sits around waiting for packets and then sends them off to ECM:

main_loop (State) ->

    receive

        { ConnectionID, Packet } ->

            send_packet(State#megaphone_state.socket, ConnectionID, Packet),

            main_loop(State);

        shutdown ->

            ok

    end.

The send_packet function is also pretty simple and just formats the packet:

send_packet(Socket, ConnectionID, Packet) ->

    PacketLength = length(Content) + 32,

    StrPacketLength = lists:flatten(io_lib:format("~10..0B", [ PacketLength ])),

    Packet = StrPacketLength ++ "|" ++ ConnectionId ++ "|" ++ Content,

    gen_tcp:send(Socket, Packet).

The next step is to refactor the megaphone module to take into account that the ECM communications logic has been moved to other modules.