async-sockets

A Clojure library for opening and working with sockets asynchronously.

Releases

async-sockets is published to clojars.org. The latest stable release is 0.1.0.

Leiningen dependency information:

[com.gearswithingears/async-sockets "0.1.0"]

Usage

This library permits the creation of socket servers and remote socket clients in idiomatic Clojure. It uses clojure.core.async channels for receiving and sending socket data but otherwise leans heavily on java.net.Socket and java.net.ServerSocket for most of the heavy lifting. At the moment, it uses a line-based idiom for all socket interactions; remote data is received and sent a line at a time, and flushed on write. Pull requests gratefully accepted.

Servers are created with (socket-server <port> [<backlog>] [<bind-addr>]). The latter two arguments are both optional and behave as specified by java.net.SocketServer. The function returns a record with a channel named :connections, which yields one AsyncSocket per incoming client connection.

Clients are created with (socket-client <port> [<address>]); address is localhost by default. Each socket, either created explicitly using this function or yielded by the :connections fields of an AsyncSocketServer, exposes two channels, an :in channel for receiving messages and an :out channel for sending messages. The raw java.net.Socket object is also available as :socket, should you need it.

To connect and send a message to a remote server example.com:

(ns user
  (:require [async-sockets.core :refer :all]
            [clojure.core.async :as async]))

(let [socket (socket-client "example.com" 12345)]
  (async/>!! (:out socket) "Hello, World")
  (close-socket-client socket))

To start an asynchronous socket server, which in this case echoes every input received:

(ns user
  (:require [async-sockets.core :refer :all]
            [clojure.core.async :as async]))
   
(defn echo-everything [socket]
  (async/go-loop []
    (when-let [line (async/<! (:in socket))]
      (async/>! (:out socket) (str "ECHO: " line))
      (recur))))
   
(let [server (socket-server 12345)]
  (async/go-loop []
    (when-let [connection (async/<! (:connections server))] 
      (echo-everything connection)
      (recur)))))

When the underlying socket closes, each channel will close automatically, both for outgoing (client) and incoming (server) sockets.

License

Copyright © 2014 Brian Guthrie (btguthrie@gmail.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.