From: Joel VanderWerf <vjoel@...>
Date: 2008-09-06T15:48:52+09:00
Subject: Re: Question About TCPServer & TCPSocket classes

Steve Lewis wrote:
> Hello Rubyists,
> 
> I've been messing around with socket programming in Ruby lately, and I've 
> hit a snag with some of my experiments.  My first, (successful), 
> experiment was to create a basic client/server script wherein the client 
> sends a string to the server, and the server responds by simply writing 
> the string back to the client...that code is as follows:
> 
> Server:
> #####################################
> require 'socket'
> 
> class PingServer < TCPServer
> 
>   def start_server
>     loop do
>       Thread.start(self.accept) do |s|
>         p "Connection accepted from server #{s.inspect}"
>         request = s.readline.gsub(/\n$/, '')
                       ^^^^^^^^

This method reads until newline, and binary data (such as Marshal.dump 
output) is not generally delimited that way. Use IO#read or Socket#recv 
instead.

If you want to read a binary message, you can do one of several things:

1. pick a delimiter char and escape that wherever it occurs within the 
binary data (yuck)

2. send a length field before sending the data, so the receiver knows 
how much to wait for

3. send one message per socket connection

4. encode the binary data in some non-binary form: e.g. base64, using 
pack("m"), and delimit using blank lines.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407