Socket

Socket:

Type:

Class

Constants:

AF_INET6 : Object.new

IPv6 protocol family

Class Socket provides access to the underlying operating system socket implementations. It can be used to provide more operating system specific functionality than the protocol-specific socket classes.

The constants defined under Socket::Constants are also defined under Socket. For example, Socket::AF_INET is usable as well as Socket::Constants::AF_INET. See Socket::Constants for the list of constants.

What's a socket?

Sockets are endpoints of a bidirectionnal communication channel. Sockets can communicate within a process, between processes on the same machine or between different machines. There are many types of socket: TCPSocket, UDPSocket or UNIXSocket for example.

Sockets have their own vocabulary:

domain: The family of protocols:

Socket::PF_INET
Socket::PF_INET6
Socket::PF_UNIX
etc.

type: The type of communications between the two endpoints, typically

Socket::SOCK_STREAM
Socket::SOCK_DGRAM.

protocol: Typically zero. This may be used to identify a variant of a protocol.

hostname: The identifier of a network interface:

a string (hostname, IPv4 or IPv6 adress or broadcast which specifies a broadcast address)
a zero-length string which specifies INADDR_ANY
an integer (interpreted as binary address in host byte order).

Quick start

Many of the classes, such as TCPSocket, UDPSocket or UNIXSocket, ease the use of sockets comparatively to the equivalent C programming interface.

Let's create an internet socket using the IPv4 protocol in a C-like manner:

s = Socket.new Socket::AF_INET, Socket::SOCK_STREAM
s.connect Socket.pack_sockaddr_in(80, 'example.com')

You could also use the TCPSocket class:

1	`s = TCPSocket.new` `'example.com',` `80`

A simple server might look like this:

require 'socket'
 
server = TCPServer.new 2000 # Server bound to port 2000
 
loop do
  client = server.accept    # Wait for a client to connect
  client.puts "Hello !"
  client.puts "Time is #{Time.now}"
  client.close
end

A simple client may look like this:

require 'socket'
 
s = TCPSocket.new 'localhost', 2000
 
while line = s.gets # Read lines from socket
  puts line         # and print them
end
 
s.close             # close socket when done

Exception Handling

Ruby's Socket implementation raises exceptions based on the error generated by the system dependent implementation. This is why the methods are documented in a way that isolate Unix-based system exceptions from Windows based exceptions. If more information on a particular exception is needed, please refer to the Unix manual pages or the Windows WinSock reference.