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metroplex

Metroplex

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Metroplex a Redis based spark/connection registry for Primus.

Installation

Metroplex is released in the npm registry and can therefor be installed using:

npm install --save metroplex

Once you've installed the module you need to tell Primus to use the plugin which is done using the primus.use method:

'use strict';
 
var http = require('http').createServer()
  , Primus = require('primus')
  , primus = new Primus(http, { transformer: 'sockjs' });
 
primus.use('metroplex', require('metroplex'));

Usage

In the example above you've seen how to add the plugin to your Primus server but not how to configure it. We have various of options that can be configured in this plugin:

  • redis: Metroplex is currently using Redis as its default back-end for storing the state of the connections. If you do not supply us with a pre-defined Redis client (or authorized) we will create a Redis client which only connects to localhost and Redis's default port number. When provided this must be an ioredis client.
  • namespace: As the databases are usually shared with other programs it's good to prefix all the data that you store, in Metroplex we prefix every key with the set namespace. The default namespace is metroplex.
  • interval: We are using "alive" suffixed keys in the database to see which node process is still alive. The interval determines the interval of these updates. When the interval is reached we update the key in the database with the current EPOCH as well as start a scan for possible dead servers and removing them. The default interval 300000 ms
  • latency: The maximum time it would take to update the alive key in Redis. This time is subtracted from the set interval so we update the key BEFORE it expires. Defaults to 2000 ms.
  • address The address or public URL on which this SPECIFIC server is reachable. Should be without path name. When nothing is supplied we try to be somewhat smart and read the address and port and server type from the server that Primus is attached to and compose an URL like: http://0.0.0.0:8080 from it.

These options should be provided in the options object of the Primus server:

primus = new Primus(http, {
  transformer: 'sockjs',
  namespace: 'metroplex',
  redis: require('redis').createClient()
});
 
primus.use('metroplex', require('metroplex'));

Metroplex

The orchestration is all done using the metroplex library which is bundled in this plugin. The Metroplex instance is exposed on the Primus instance when you use this plugin:

primus.metroplex.servers(function (err, servers) {
  console.log('registered servers:', servers);
});

The following public methods are available.

metroplex.servers

metroplex.servers(fn)

List all the servers in our current registry.

metroplex.servers(function (err, servers) {
  console.log(servers);
});

metroplex.spark

metroplex.spark(id, fn)

Get the server for the given spark id. It does not check if the spark is hosted on the current server. That's up to the developer to implement.

metroplex.spark(id, function (err, server) {
  console.log(server);
});

metroplex.sparks

metroplex.sparks(sparks, fn)

Get the servers for each id in the given sparks array. It will return an object and just like metroplex.spark it does not check if the spark is hosted on the current server.

Omega Supreme integration

If you load the omega-supreme plugin before metroplex, you can use some additional convenience methods. These methods are added to the primus.forward object:

forward.broadcast

forward.broadcast(msg, fn)

Broadcast a message to all sparks in the cluster.

forward.broadcast('data', function (err, result) {
  // result is an object with details about the result of the operation. 
  console.log(result);
});

forward.sparks

forward.sparks(ids, msg, fn)

Send a message to a set of sparks in the cluster.

forward.sparks(['ad8a-280z-18', 'y97x-42480-13'], 'data', function (err, result) {
  console.log(result);
});

forward.spark

forward.spark(id, msg, fn)

Send a message to a single spark in the cluster.

forward.spark('ad8a-280z-18', 'data', function (err, result) {
  console.log(result);
});

License

MIT

Metroplex