SSE (Server Sent Events) library for node.js.

sselib is a implementation of the server-side part of the [SSE] 1 protocol written in Coffee Script for the node.js platform.

Installation

Install with npm:

$ npm install sselib

Requirements

None, tested on node.js 0.6 >

Connect and Express Middleware

sselib can be used as a middleware for applications following the Connect convention.

Example

Javascript

    var sselib = require('sselib'),
    express = require('express');

    var app = express();
    
    app.use(sselib.middleware());
    
    app.get('/events', function(req, res) {
      res.sse({
        event: 'update',
        data: 'I am a stray cat.'
      });
        
    });

    app.listen(3000);

Coffeescript

    sselib = require 'sselib'
    express = require 'express'

    app = express()

    app.use sselib.middleware()
    
    app.get '/events', (req, res) ->
      res.sse
        event: 'update'
        data: 'I am a stray cat.'

Options

You can pass options when initializing the middleware.

    app.use(sselib.middleware({
      retry: 5*1000,
      keepAlive: 15*1000,
      compatibility: true
    });

A already initialized connection can use res.sse.set in order to set a new value for the option. Setting longer retry values and closing connections can be a effective strategy when servers are under high load.

    app.get('/events', function(req, res) {
      res.sse.set('retry', 30*1000);
    });

res.sse.get(option) respectively gets the current configuration.

retry

The time in milliseconds for client reconnects. Default is 5 seconds.
Set to false in order to disable.

keepAlive

Sends pseudo keep alive heartbeats in order to keep the connection open. The value is the amount of milliseconds between each keepAlive heartbeat. Default is 15 seconds.
Set to false in order to disable.

compatibility

"Quirks mode". Adds support for some polyfills and the way MSIE handles XDomainRequest. Default is true
Set to false in order to disable.

Use as a library to serialize data for your own transmission

Example

    var sselib = require('sselib');

    console.log(sselib.event("notice")); // "event: notice\n"
    console.log(sselib.data("Hello there!")); // "data: Hello there!\n\n"

    // or:
    
    sselib.data("Hello there!", function(err, result) {
      if (err) {
        // print the error to console
        console.log(err);
        return;
      }
      console.log(result) // "data: Hello there!\n\n"
    });

Serializers

sselib.comment(comment [, callback])

Returns a SSE-serialized comment string representing a comment (please note that comments are invisible to browser clients).

sselib.event(event [, callback])

Returns a SSE-serialized event string that can be used with a following data type to trigger a event in the browser.

sselib.id(id [, callback])

Returns a SSE-serialized id string. If called without id it will use a UNIX timestamp as the id.

sselib.data(data [, callback])

Returns a SSE-serialized data string.

sselib.message(obj [, callback])

message is provided as a meta-serializer. It will return a SSE-serialized string from a message object you pass in.

sselib.headers([callback])

Returns a Object containing valid HTTP-headers suitable for a http.ServerResponse.

Concepts

Message Object

A message object is simply a javascript object containing the data and event keys, it can also optionally be given a id key.

Example

{event: 'update', data: 'I am a stray cat.', id: 789}

License

BSD (see LICENSE.md)

Made by massförströelse