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|ab|

|ab| is a subproject of Autobahn and provides an open-source implementation of The Web Application Messaging Protocol (WAMP) .

WAMP runs on top of WebSocket and adds asynchronous Remote Procedure Calls and Publish & Subscribe.

|ab| runs in the browser as well as in Node.js

What can I do with this stuff?

|ab| makes distributed, realtime Web applications easy: it provides the infrastructure for both distributing live updates to all connected clients (using the PubSub messaging pattern) and for calling remote procedures in different backend components (using RPC).

It is ideal for distributed, multi-client and server applications, such as multi-user database-drive business applications, real-time charts, sensor networks (IoT), instant messaging or MMOGs (massively multi-player online games).

The protocol that |ab| uses, WAMP, enables application architectures with application code distributed freely across processes and devices according to functional aspects. All WAMP clients are equal in that they can publish events and subscribe to them, can offer a procedure for remote calling and call remote procedures.

Since WAMP implementations exist for multiple languages, this extends beyond JavaScript clients: WAMP applications can be polyglot. Application components can be implemented in a language and run on a device which best fit the particular use case. Applications can span the range from embedded IoT sensors right to mobile clients or the browser - using the same protocol.

Show me some code

The following example implements all four roles that |ab| offers

  • Publisher
  • Subscriber
  • Caller (calls a remote procedure)
  • Callee (offers a remote procedure)

The code runs unaltered in the browser or Node.js!

var connection = new autobahn.Connection({
         url: 'ws://127.0.0.1:9000/',
         realm: 'realm1'
      });

connection.onopen = function (session) {

   // 1) subscribe to a topic
   function onevent(args) {
      console.log("Event:", args[0]);
   }
   session.subscribe('com.myapp.hello', onevent);

   // 2) publish an event
   session.publish('com.myapp.hello', ['Hello, world!']);

   // 3) register a procedure for remoting
   function add2(args) {
      return args[0] + args[1];
   }
   session.register('com.myapp.add2', add2);

   // 4) call a remote procedure
   session.call('com.myapp.add2', [2, 3]).then(
      function (res) {
         console.log("Result:", res);
      }
   );
};

connection.open();

Features

  • supports WAMP v2, works with any WAMP server
  • works both in the browser and Node.js
  • provides asynchronous RPC and PubSub messaging patterns
  • easy to use Promise-based API
  • pluggable promises/deferreds: use when.js (built-in), jQuery , Dojo , ECMA Script 6 or others
  • no dependencies
  • small size (244kB source, 111kB minified, 33kB compressed)
  • Open-Source (MIT License)

Where to start

:doc:`gettingstarted` gives a brief overview of requirements, how to get |ab|, and where to get an application router which you need to route the application traffic of your JavaScript application.

The :doc:`programming` gives an overview of how to connect your application components, and do basic RPC and PubSub.

The :doc:`examples overview page <examples_overview>` lists code examples covering a broader range of uses cases and advanced WAMP features.

The Demos give the opportunity to play around with some live sample applications made using |ab| and Crossbar.io, an application router which uses WAMP. The demo source code can be found on GitHub.

The :doc:`reference` provides details for the entire API.

Note

The documentation for older versions of |ab|, which implement WAMP v1, is still available as :doc:`legacy documentation <reference_wampv1>`. The current version of |ab| no longer supports WAMP v1. WAMP v2 adds a lot of features and some completely new capabilities, so consider upgrading.

Acknowledgements

|ab| includes code from the following open-source projects

Special thanks to the Coders with an Unhealthy Javascript Obsession for creating when.js - A lightweight Promise and when() implementation, plus other async goodies.

.. toctree::
   :hidden:

   Home <self>
   gettingstarted
   programming
   examples_overview
   building
   reference