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Chainsaw App v2

A complete rewrite of the old convoluted chainsaw codebase to make it:

  • Cleaner in terms of code
  • Simpler to run (One process, versus many)
  • Easy to extend (based on a simple publisher model)

With the whole goal of making real time event streams (pulling events from external sources) as simple as possible.

Originally built for Rails Rumble 2010 like I built prior versions for earlier rumbles.

Getting Started

First, make sure you have node.js and npm installed.

Writing a Publisher

Publishers are just the general idea of a configurable item which can push things to the notifications list. For example, to implement a simple publisher, you can do (in CoffeeScript):

Base = require('chainsaw/base).Base

class MyPublisher extends Base
  name: "my-publisher"
  
  setup: ->
    # Called automatically.
    stored_name = @get "name" # gets name in the my-publisher key in the configuration
    setInterval((=>
      @emit some: "data"
    ), 10000)

You define a setup method that starts doing processing, configure a name (and optionally, namespace for events and configNamespace for the configuration json namespace). This simple yet flexible architecture makes it possible to build a wide variety of publishers.

Configuration

Chainsaw uses a standard config.json file which uses nested keys according to:

  • Chainsaw Settings (chainsaw)
  • Redis settings (redis)
  • Publisher settings (either the publisher name or the configNamespace value on a given publisher).

An example of this can be seen in the config.example.json file which contains all options. Please note that most options are optional.

Lastly, in the case of the following, they can also be overridden by an environment variable:

  • chainsaw.listen.host (by HOST)
  • chainsaw.listen.port (by PORT)
  • chainsaw.redis.host (by REDIS_HOST)
  • chainsaw.redis.port (by REDIS_HOST)
  • chainsaw.redis.password (by REDIS_PASSWORD)
  • chainsaw.redis.maxHistory (by REDIS_MAXHISTORY)

The Public JavasScript Portion

Please note the public portion can be found in public/ and that your application uses Chainsaw. It'd be pretty simple to port it to use something other than jQuery but that is left as an exercise for the reader.

Developing Chainsaw

To develop chainsaw, you'll also need to install coffee-script via:

npm install coffee-script