sombrero-node's Introduction

Sombrero Node

Node of a Sombrero cluster. Uses Skiff (A Raft implementation) underneath.

As a leader, creates an independent RPC server for servicing requests from followers.
As a follower, forwards the write requests to the leader.
As a follower, makes sure that the leader writes to the issuing follower before returning.
Because of this last point, it implements a read-your-writes on a follower.

Install

$ npm install sombrero-node --save

Require

var Node = require('sombrero-node');

Create

var url = 'tcp+msgpack://localhost:8000';
var port = 7000;
var options = {
  skiff: {
    dbPath: '/path/to/my/leveldb/dir'
  },
  port: port
};

var node = Node(url, options);

Options

skiff: all the options supported by skiff
port: the TCP port for exposing the RPC server. Defaults to 5201.
transport: a transport module provider. Defaults to this.
gossip: an object with the following attributes:
- port: gossip port. defaults to 8217

Use

A Sombrero node implements the level-up API.

You can also extend the client with level-* plugins, including sublevel.

.join(url, options, cb)

Joins a node given its URL. Options should contain the hostname and port of the node Sombrero RPC server.

Example:

var options = {
  hostname: 'localhost',
  port: 8071
};

node.join('tcp+msgpack://hostname:8000', options, function(err) {
  if (err) throw err;
  console.log('joined');
});

.leave(url, cb)

Leaves a node given its URL.

.close(cb)

Closes the server and the skiff node.

Events

A Sombrero node emits the same events as a Skiff node.

Setting up a cluster

To boot a cluster, start a node and wait for it to become a leader. Then, create each additional node in the standby mode (options.skiff.standby: true) and do leader.join(nodeURL).

See this test for an actual implementation.