Parsing Headers and Bodies

Previously...

• I resolved to use a single process to respond to ejabberd_http.
• I did an analysis of the event sequence that should take place in order to use a single process.
• I made some plans about how to create megaphone_tcp.

I remember a comment that James Rumbaugh, one of guys behind UML, once said:

Some objects tell others to do stuff, other objects do what they're told.

I thought that contrast nicely summarizes the first part of coding for megaphone_tcp.

At a larger level, meaphone_tcp is very much a "do what you're told" style of module: on startup, it fires up a new process for itself, but doesn't try to start up anything else:

start(Socket) ->

    Pid = spawn(megaphone, start_receive, [Socket]),

    gen_tcp:controlling_process(Socket, Pid).

start_receive just sets up the system for the first iteration through the main loop:

start_receive (Socket) ->

    receive_loop(Socket, start, undefined).

The module is currently centered around going through the steps outlined in the post previous to this one.  The first step is to figure out if you have a complete header:

receive_loop (Socket, OldState, LeftOvers) ->

    case gen_tcp:recv(Socket, 0) of

        { ok, Binary } ->

            { PacketLength, ConnectionID, Data } = receive_header(Socket, LeftOvers, Binary),

            { Packet, NewLeftOvers } = receive_packet_body (Socket, Data, PacketLength, ConnectionID),

            give_packet_to_megaphone (ConnectionID, Packet),

            receive_loop(Socket, undefined, NewLeftOvers);

        Other ->

            gen_tcp:close(Socket)

    end.

The rest of the code is left as an exercise for the reader.

That didn't work, did it?

I'll post the rest of the code as I write it.  Which will be real soon.  Honest.