Aleph is a framework for asynchronous communication, built on top of Netty and Lamina. It can do all kinds of things, including:
Aleph conforms to the interface described by Ring, with one small difference: the request and response are decoupled.
(use 'lamina.core 'aleph.http)
(defn hello-world [channel request]
(enqueue channel
{:status 200
:headers {"content-type" "text/html"}
:body "Hello World!"}))
(start-http-server hello-world {:port 8080})For more on HTTP functionality, read the wiki.
This snippet prints out a never-ending sequence of tweets:
(use 'lamina.core 'aleph.http)
(let [ch (:body
(sync-http-request
{:method :get
:basic-auth ["aleph_example" "_password"]
:url "http://stream.twitter.com/1/statuses/sample.json"}))]
(doseq [tweet (lazy-channel-seq ch)]
(println tweet)))A more in-depth exploration of this example can be found here.
Making a simple chat client is trivial. In this, we assume that the first message sent by the client is the user's name:
(use 'lamina.core 'aleph.http)
(def broadcast-channel (channel))
(defn chat-handler [ch handshake]
(receive ch
(fn [name]
(siphon (map* #(str name ": " %) ch) broadcast-channel)
(siphon broadcast-channel ch))))
(start-http-server chat-handler {:port 8080 :websocket true})Here is a basic echo server:
(use 'lamina.core 'aleph.tcp)
(defn echo-handler [channel client-info]
(siphon channel channel))
(start-tcp-server echo-handler {:port 1234})For more on TCP functionality, visit the wiki.
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Other protocols are supported, and still more are forthcoming.
Aleph is meant to be a sandbox for exploring how Clojure can be used effectively in this context. Contributions and ideas are welcome.
For more information, visit the wiki or the API documentation. If you have questions, please visit the mailing list.