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Package detail

pm2-axon

Unitech6.3mMIT4.0.1

High-level messaging & socket patterns implemented in pure js

zmq, zeromq, pubsub, socket, emitter, ipc, rpc

readme

Axon

Axon is a message-oriented socket library for node.js heavily inspired by zeromq. For a light-weight UDP alternative you may be interested in punt.

Build Status

Installation

$ npm install axon

Features

  • message oriented
  • automated reconnection
  • light-weight wire protocol
  • mixed-type arguments (strings, objects, buffers, etc)
  • unix domain socket support
  • fast (~800 mb/s ~500,000 messages/s)

Events

  • close when server or connection is closed
  • error (err) when an un-handled socket error occurs
  • ignored error (err) when an axon-handled socket error occurs, but is ignored
  • socket error (err) emitted regardless of handling, for logging purposes
  • reconnect attempt when a reconnection attempt is made
  • connect when connected to the peer, or a peer connection is accepted
  • disconnect when an accepted peer disconnects
  • bind when the server is bound
  • drop (msg) when a message is dropped due to the HWM
  • flush (msgs) queued when messages are flushed on connection

Patterns

  • push / pull
  • pub / sub
  • req / rep
  • pub-emitter / sub-emitter

Mixed argument types

Backed by node-amp-message you may pass strings, objects, and buffers as arguments.

push.send('image', { w: 100, h: 200 }, imageBuffer);
pull.on('message', function(type, size, img){});

Push / Pull

PushSockets distribute messages round-robin:

var axon = require('axon');
var sock = axon.socket('push');

sock.bind(3000);
console.log('push server started');

setInterval(function(){
  sock.send('hello');
}, 150);

Receiver of PushSocket messages:

var axon = require('axon');
var sock = axon.socket('pull');

sock.connect(3000);

sock.on('message', function(msg){
  console.log(msg.toString());
});

Both PushSockets and PullSockets may .bind() or .connect(). In the following configuration the push socket is bound and pull "workers" connect to it to receive work:

push bind

This configuration shows the inverse, where workers connect to a "sink" to push results:

pull bind

Pub / Sub

PubSockets send messages to all subscribers without queueing. This is an important difference when compared to a PushSocket, where the delivery of messages will be queued during disconnects and sent again upon the next connection.

var axon = require('axon');
var sock = axon.socket('pub');

sock.bind(3000);
console.log('pub server started');

setInterval(function(){
  sock.send('hello');
}, 500);

SubSocket simply receives any messages from a PubSocket:

var axon = require('axon');
var sock = axon.socket('sub');

sock.connect(3000);

sock.on('message', function(msg){
  console.log(msg.toString());
});

SubSockets may optionally .subscribe() to one or more "topics" (the first multipart value), using string patterns or regular expressions:

var axon = require('axon');
var sock = axon.socket('sub');

sock.connect(3000);
sock.subscribe('user:login');
sock.subscribe('upload:*:progress');

sock.on('message', function(topic, msg){

});

Req / Rep

ReqSocket is similar to a PushSocket in that it round-robins messages to connected RepSockets, however it differs in that this communication is bi-directional, every req.send() must provide a callback which is invoked when the RepSocket replies.

var axon = require('axon');
var sock = axon.socket('req');

sock.bind(3000);

sock.send(img, function(res){

});

RepSockets receive a reply callback that is used to respond to the request, you may have several of these nodes.

var axon = require('axon');
var sock = axon.socket('rep');

sock.connect(3000);

sock.on('message', function(img, reply){
  // resize the image
  reply(img);
});

Like other sockets you may provide multiple arguments or an array of arguments, followed by the callbacks. For example here we provide a task name of "resize" to facilitate multiple tasks over a single socket:

var axon = require('axon');
var sock = axon.socket('req');

sock.bind(3000);

sock.send('resize', img, function(res){

});

Respond to the "resize" task:

var axon = require('axon');
var sock = axon.socket('rep');

sock.connect(3000);

sock.on('message', function(task, img, reply){
  switch (task) {
    case 'resize':
      // resize the image
      reply(img);
      break;
  }
});

PubEmitter / SubEmitter

PubEmitter and SubEmitter are higher-level Pub / Sub sockets, using the "json" codec to behave much like node's EventEmitter. When a SubEmitter's .on() method is invoked, the event name is .subscribe()d for you. Each wildcard (*) or regexp capture group is passed to the callback along with regular message arguments.

app.js:

var axon = require('axon');
var sock = axon.socket('pub-emitter');

sock.connect(3000);

setInterval(function(){
  sock.emit('login', { name: 'tobi' });
}, 500);

logger.js:

var axon = require('axon');
var sock = axon.socket('sub-emitter');

sock.bind(3000);

sock.on('user:login', function(user){
  console.log('%s signed in', user.name);
});

sock.on('user:*', function(action, user){
  console.log('%s %s', user.name, action);
});

sock.on('*', function(event){
  console.log(arguments);
});

Socket Options

Every socket has associated options that can be configured via get/set.

  • identity - the "name" of the socket that uniqued identifies it.
  • retry timeout - connection retry timeout in milliseconds [100] (0 = do not reconnect)
  • retry max timeout - the cap for retry timeout length in milliseconds [5000]
  • hwm - the high water mark threshold for queues [Infinity]

Binding / Connecting

In addition to passing a portno, binding to INADDR_ANY by default, you may also specify the hostname via .bind(port, host), another alternative is to specify the url much like zmq via tcp://<hostname>:<portno>, thus the following are equivalent:

sock.bind(3000)
sock.bind(3000, '0.0.0.0')
sock.bind('tcp://0.0.0.0:3000')

sock.connect(3000)
sock.connect(3000, '0.0.0.0')
sock.connect('tcp://0.0.0.0:3000')

You may also use unix domain sockets:

sock.bind('unix:///some/path')
sock.connect('unix:///some/path')

Protocol

Axon 2.x uses the extremely simple AMP protocol to send messages on the wire. Codecs are no longer required as they were in Axon 1.x.

Performance

Preliminary benchmarks on my Macbook Pro based on 10 messages per tick as a realistic production application would likely have even less than this. "better" numbers may be acheived with batching and a larger messages/tick count however this is not realistic.

64 byte messages:


      min: 47,169 ops/s
     mean: 465,127 ops/s
   median: 500,000 ops/s
    total: 2,325,636 ops in 5s
  through: 28.39 mb/s

1k messages:


      min: 48,076 ops/s
     mean: 120,253 ops/s
   median: 121,951 ops/s
    total: 601,386 ops in 5.001s
  through: 117.43 mb/s

8k messages:


      min: 36,496 ops/s
     mean: 53,194 ops/s
   median: 50,505 ops/s
    total: 266,506 ops in 5.01s
  through: 405.84 mb/s

`

32k messages:


      min: 12,077 ops/s
     mean: 14,792 ops/s
   median: 16,233 ops/s
    total: 74,186 ops in 5.015s
  through: 462.28 mb/s

What's it good for?

Axon are not meant to combat zeromq nor provide feature parity, but provide a nice solution when you don't need the insane nanosecond latency or language interoperability that zeromq provides as axon do not rely on any third-party compiled libraries.

Running tests

$ npm install
$ make test

Authors

License

MIT

changelog

=======

2.0.1 / 2014-09-09

  • fix Floating-point durations to setTimeout may cause infinite loop

2.0.0 / 2014-02-25

  • refactor to use the AMP protocol. Closes #577
  • remove old codec support

1.0.0 / 2013-08-30

  • change Socket#connect() to use inaddr_any as well

0.6.1 / 2013-04-13

  • fix Socket#close() callback support
  • add callback to reply() when peer is gone

0.6.0 / 2013-04-13

  • add optional reply() callback. Closes #95
  • add support for optional req.send() callback. Closes #89

0.5.2 / 2013-04-09

  • add sock.queue array for logging / debugging etc
  • fix connection queue flush which may drop messages on connection

0.5.1 / 2013-03-01

  • add exit() to HWM example
  • add better HWM example
  • fix: ignore closed sockets on reply(). fixes #82

0.5.0 / 2013-01-01

  • add HWM support. Closes #19
  • add ability to pass a callback in to the Socket.close method.
  • update benchmarks. Closes #72
  • remove batching

0.4.6 / 2012-11-15

  • fix round-robin write to unwritable socket

0.4.5 / 2012-10-30

  • add more network errors to be ignored
  • refactor SubEmitter
  • refactor PubEmitter
  • fix exponential backoff

0.4.4 / 2012-10-29

  • fix round-robin global var leak for fallback function. Closes #66

0.4.3 / 2012-10-27

  • add 30% throughput increase for sub-emitter by removing some indirection
  • fix PubSocket#flushBatch() in order to avoid writing to not writable sockets [AlexeyKupershtokh]

0.4.2 / 2012-10-18

  • add 30% throughput increase for sub-emitter by removing some indirection
  • add escaping of regexp chars for SubSocket#subscribe()
  • fix non-multipart SubEmitterSocket logic

0.4.1 / 2012-10-16

  • add removal of sockets on error
  • add handling of ECONNRESET, ECONNREFUSED, and EPIPE. Closes #17
  • add immediate closing of sockets on .close()
  • fix "bind" event. Closes #53
  • fix 'close' event for server sockets
  • remove "stream" socket type for now

0.4.0 / 2012-10-12

  • add emitter wildcard support
  • add sub socket subscription support
  • add pub-emitter
  • add sub-emitter
  • perf: remove .concat() usage, ~10% gain
  • remove greetings

0.3.2 / 2012-10-08

  • change prefix fix to reply() only

0.3.1 / 2012-10-08

  • add fix for reply(undefined)

0.3.0 / 2012-10-05

  • add Socket#address() to help with ephemeral port binding. Closes #39
  • add default identity of PID. Closes #35
  • remove examples for router/dealer

0.2.0 / 2012-09-27

  • add default random identity
  • add req.send() callback support
  • remove router / dealer
  • change ReqSocket to round-robin send()s

0.1.0 / 2012-09-24

  • add router socket [gjohnson]
  • add dealer socket [gjohnson]
  • add req socket [gjohnson]
  • add rep socket [gjohnson]
  • add multipart support [gjohnson]
  • add .set() / .get() configuration methods
  • add tcp://hostname:port support to .bind() and .connect(). Closes #16
  • add make bm
  • add Batch#empty()
  • remove Socket#option()

0.0.3 / 2012-07-14

  • add resize example
  • add debug() instrumentation
  • add PullSocket bind support
  • add Parser