# axon

**Repository Path**: mirrors_Unitech/axon

## Basic Information

- **Project Name**: axon
- **Description**: message-oriented socket library for node.js heavily inspired by zeromq
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-19
- **Last Updated**: 2026-02-14

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## 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](https://github.com/visionmedia/punt).

[![Build Status](https://travis-ci.org/visionmedia/axon.png)](https://travis-ci.org/visionmedia/axon)

## Installation

    $ npm install axon

## Features

  - message oriented
  - automated reconnection
  - light-weight wire protocol
  - supports arbitrary binary message (msgpack, json, BLOBS, etc)
  - supports JSON messages out of the box
  - 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

## Push / Pull

`PushSocket`s distribute messages round-robin:

```js
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:

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

sock.connect(3000);

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

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

![push bind](http://f.cl.ly/items/473u3m1a0k1i0J0I3s04/ss-push.png)

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

![pull bind](http://f.cl.ly/items/3Y0j2v153Q0l1r373i0H/ss-pull.png)

## Pub / Sub

`PubSocket`s 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.

```js
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`:

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

sock.connect(3000);

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

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

```js
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){

});
```

## Req / Rep

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

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

sock.bind(3000);

sock.send(img, function(res){

});
```

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

```js
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:

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

sock.bind(3000);

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

});
```

 Respond to the "resize" task:

```js
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 / 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:

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

sock.connect(3000);

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

logger.js:

```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);
});
```

## 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]
  - `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

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.

## Codecs

To define a codec simply invoke the `axon.codec.define()` method, for example
here is the JSON codec:

```js
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);
});
```

## 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

  - [visionmedia](http://github.com/visionmedia)
  - [gjohnson](https://github.com/gjohnson)

## Links

  - [Screencast](https://vimeo.com/45818408)
  - [Axon RPC](https://github.com/visionmedia/axon-rpc)
  - [msgpack codec](https://github.com/visionmedia/axon-msgpack)

## License

  MIT