Axon is a message-oriented socket library for node.js heavily inspired by zeromq.
$ npm install axon
close when server or connection is closederror (err) when an-handled socket error occursignored error (err) when an axon-handled socket error occurs, but is ignoredsocket error (err) emitted regardless of handling, for logging purposesreconnect attempt when a reconnection attempt is madeconnect when connected to the peer, or a peer connection is accepteddisconnect when an accepted peer disconnectsbind when the server is bounddrop (msg) when a message is dropped due to the HWMflush (msgs) queued when messages are flushed on connectionPushSockets distribute messages round-robin:
var axon = require('axon')
, 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')
, 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:
This configuration shows the inverse, where workers connect to a "sink" to push results:
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')
, 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')
, 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')
, sock = axon.socket('sub');
sock.connect(3000);
sock.subscribe('user:login');
sock.subscribe('upload:*:progress');
sock.on('message', function(topic, msg){
});
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')
, 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')
, 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')
, sock = axon.socket('req');
sock.bind(3000);
sock.send('resize', img, function(res){
});
Respond to the "resize" task:
var axon = require('axon')
, sock = axon.socket('rep');
sock.connect(3000);
sock.on('message', function(task, img, reply){
switch (task.toString()) {
case 'resize':
// resize the image
reply(img);
break;
}
});
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')
, sock = axon.socket('pub-emitter');
sock.connect(3000);
setInterval(function(){
sock.emit('login', { name: 'tobi' });
}, 500);
logger.js:
var axon = require('axon')
, 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);
});
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]retry max timeout - the cap for retry timeout length in milliseconds [5000]hwm - the high water mark threshold for queues [Infinity]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')
The wire protocol is simple and very much zeromq-like, where <length> is
a BE 24 bit unsigned integer representing a maximum length of roughly ~16mb. The <meta>
data byte is currently only used to store the codec, for example "json" is simply 1,
in turn JSON messages received on the client end will then be automatically decoded for
you by selecting this same codec.
octet: 0 1 2 3 <length>
+------+------+------+------+------------------...
| meta | <length> | data ...
+------+------+------+------+------------------...
Thus 5 bytes is the smallest message axon supports at the moment. Later if necessary we can use the meta to indicate a small message and ditch octet 2 and 3 allowing for 3 byte messages.
To define a codec simply invoke the axon.codec.define() method, for example
here is the JSON codec:
var axon = require('axon');
axon.codec.define('json', {
encode: JSON.stringify,
decode: JSON.parse
});
Note: codecs must be defined on both the sending and receiving ends, otherwise
axon cannot properly decode the messages. You may of course ignore this
feature all together and simply pass encoded data to .send().
To use a codec in a socket pair, use the format(<codec name>) command. For example, to send json over a req/rep socket pair:
var axon = require('axon')
, req = axon.socket('req')
, rep = axon.socket('rep')
req.format('json');
req.bind(3000);
rep.format('json');
rep.connect(3000);
rep.on('message', function(obj, reply){
reply(obj);
});
req.send({ hello: 'World' }, function(res){
console.log(res);
});
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
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.
$ npm install
$ make test
MIT
FAQs
High-level messaging & socket patterns implemented in pure js
We found that axon demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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