node-caster

Multicast Service Discovery

Caster provides a multicast server with middleware support. json, hash, and crypto middleware is included.

Node implements service discovery on top of Caster.

install

npm install caster

api

Caster - a multicast server

Stability: 2 - Unstable

example

var caster = require('caster');

var server = caster.create();

server.use(
    caster.middleware.json(),
    caster.middleware.hash({secret: 'mySecretHashPrefix'}),
    caster.middleware.crypto({key: 'mySecretKey'})
);

server.on('message', function(message, remote) {
  console.log(message, remote);
});

server.bind(function(err) {
  if (err) {
    console.log(err);
  } else {
    server.send({hello: 'world'}, function(err, bytes) {
      console.log(err, bytes);
      server.close();
    });
  }
});

caster.create(opt_options)

Creates a new Caster server. Caster is an EventEmitter.

opt_options is an optional Object.

{
  multicast: '224.0.0.42',
  address: '0.0.0.0',
  port: 10101,
  loopback: true,
  ttl: 64
}

Note: All nodes have to use the same multicast address & port to be able to communicate.

server.use(var_middleware)

Adds middleware.

server.use(
    caster.middleware.json(),
    caster.middleware.hash(),
    caster.middleware.crypto()
);

The middleware execution order, resulting from the above example, would be json.tx -> hash.tx -> crypto.tx for outgoing, and crypto.rx -> hash.rx -> json.rx for incoming messages.

server.send(message, opt_callback)

Sends a message to all listening multicast servers.

message is a Buffer.

opt_callback is an optional function(err, bytes). A possible error is emitted when no callback is set.

server.bind(opt_callback)

Enables the multicast udp socket.

opt_callback is an optional function(err). A possible error is emitted when no callback is set.

server.close(opt_callback)

Closes the socket. Allows to bind() again with the same caster object.

opt_callback is an optional function().

Event: 'message'

function(message, remote)

message is a Buffer.

remote is an object with address and port.

Event: 'error'

function(err)

middleware

An example middleware object:

{
  name: 'json',
  tx: function(message, next) {...},
  rx: function(message, remote, next) {...}
}

middleware.crypto(opt_options)

Creates a new crypto middleware to encrypt outgoing & decrypt incoming messages.

opt_options is an optional Object.

{
  key: '09dfDim3ZqzXvfkun6',
  algorithm: 'aes256'
}

middleware.hash(opt_options)

Creates a new hash middleware to hash outgoing & verify incoming messages.

opt_options is an optional Object.

{
  secret: '9ve2cND;d3"Vs',
  algorithm: 'sha1'
}

middleware.json()

Creates a new json middleware to allow usage of a stringifyable object instead of a Buffer as message.

Node - a service discovery server

Stability: 2 - Unstable

example

var node = require('caster').createNode({
  meta: {
    type: 'http',
    port: 8080
  }
});

node.on('up', function(remote) {
  console.log('node up:', remote.id, remote.meta);
});

node.on('down', function(remote) {
  console.log('node down:', remote.id, remote.meta);
});

node.on('message', function(message, remote) {
  console.log(remote.id + ':', message);
});

node.up(function(err) {
  if (err) {
    console.log(err);
  } else {
    console.log('caster node running on ' +
        node.multicast + ':' + node.port);
  }
});

caster.createNode(opt_options)

Creates a new Node object. Node is an EventEmitter and uses Caster.

opt_options is an optional Object.

{
  id: null, // your node's id, randomized if not set
  meta: null, // your node's metadata that is transmitted with every heartbeat
  expose: true, // when false, no heartbeat messages are send
  heartbeat: 1000, // heartbeat interval in ms
  timeout: 2000, // timeout until a remote node is declared down

  // caster options
  multicast: '224.0.0.42',
  port: 10101,
  ttl: 64,

  // caster middleware options
  hash: true, // enable message hashing
  hashSecret: null, // hash secret
  hashAlgorithm: 'sha1', // hash algorithm
  crypto: false, // enable message encryption
  cryptoKey: null, // encryption key
  cryptoAlgorithm: 'aes256' // encryption algorithm
}

node.up(opt_callback)

Starts up the node.

opt_callback is an optional function(err). A possible error is emitted when no callback is set.

node.down(opt_callback)

Shuts down the node.

opt_callback is an optional function().

node.send(message, opt_callback)

Sends a message to other multicast nodes.

message is a String, Number or Object.

opt_callback is an optional function(err, bytes). A possible error is emitted when no callback is set.

node.nodes

An object with all currently seen nodes.

{
  node857631295: {
    id: 'node857631295',
    address: '10.0.0.23',
    firstSeen: 1340351517064,
    lastSeen: 1340351517064,
    meta: {...}
  },
  ...
}

Event: 'message'

function(message, remote)

message is the received & parsed json object.

remote is the object stored in node.nodes.

Event: 'error'

function(Error)

Event: 'up'

Emitted when a remote node is discovered.

function(remote)

remote is the object stored in node.nodes.

Event: 'down'

Emitted when a remote node disappeared.

function(remote)

remote is the object just removed from node.nodes.

tests

make install
make jshint
make test
make test-cov

license

(The MIT License)

Copyright (c) 2012 Malte-Thorben Bruns <skenqbx@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.