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Clojure web application library: abstracts HTTP to allow modular and concise webapps

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Ring is a Clojure web applications library inspired by Python’s WSGI and Ruby’s
Rack. By abstracting the details of HTTP into a simple, unified API, Ring allows
web applications to be constructed of modular components that can be shared among
a variety of applications, web servers, and web frameworks.

The SPEC file at the root of this distribution for provides a complete
description of the Ring interface.

Quick Start

First clone the Ring source and download Ring’s dependencies:

git clone git:// cd ring ant deps

To see a live “Hello World” Ring app, run:

java -Djava.ext.dirs=deps clojure.main src/ring/examples/hello_world.clj

Now visit http://localhost:8080/ in your browser; the Ring app will respond
to your request with a simple HTML page indicating the time of day.

To see a more sophisticated Ring app, run:

java -Djava.ext.dirs=deps clojure.main src/ring/example/wrapping.clj
  • If you request http://localhost:8080/ in your browser the ring.dump
    handler will respond with an HTML page representing the request map that it
    received (see the SPEC for details on the request map).
  • If you request http://localhost:8080/clojure.png, the ring.file
    middleware will detect that there is a clojure.png file in the app’s
    public directory and return that image as a response.
  • If you request http://localhost:8080/error, the app will produce an error
    that will be caught by the middleware, which will in
    turn return a readable stacktrace as the HTML response.

Included Libs

  • ring.adapter.jetty: Adapter for the Jetty webserver.
  • ring.adapter.httpcore: Adapter for the Apache HttpCore webserver.
  • ring.middleware.file: Middleware that serves static files out of a public
  • ring.middleware.file-info: Middleware that augments response headers with
    info about File responses.
  • ring.middleware.static: Middleware that serves static files with specified
    prefixes out of a public directory.
  • Middleware that catches exceptions and
    displays readable stacktraces for debugging.
  • ring.middleware.reload: Middleware to automatically reload selected libs
    before each requests, minimizing server restarts.
  • ring.handler.dump: Handler that dumps request maps as HTML responses for
  • ring.util.builder: Helpers for composing Ring apps from multiple handlers
    and middleware.
  • ring.util.lint: Linter for the Ring interface, ensures compliance with the
    Ring spec.
  • ring.example.*: Various example Ring apps.


Ring is being actively developed; you can track its progress and contribute at
the project’s GitHub page.

To run all the Ring unit tests:

java -Djava.ext.dirs=deps clojure.main test/ring/run.clj

You can learn more about Ring’s dependencies at the following sites:


This project borrows heavily from Ruby’s Rack and Python’s WSGI, and I thank the communities developing and supporting those projects.

Copyright © 2009 Mark McGranaghan and released under an MIT license.
Clojure logo by Tom Hickey.

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