RediLine

Redis Backed Timeline

Rediline is a ruby library which intends to allow you to create timelines for your users in ruby.

Rediling has been built with the idea to make it compatible with any other ORM possible. Whether your users and objects are in SQL, MongoDB, CouchDB or anything else, you should be able to use it.

There are several requirements though.

• The ORM should provide an ActiveModel::Calbacks similar API (most ORM depends of it anyway)
• The ORM should provide a #find method to query the objects (if it does not, you can use complex queries though).

You should also be able to use Rediling in a non-rails application. Sinatra for example. There are be dependencies to ActiveSupport and ActiveModel though.

As we're using ActiveSupport (mainly for #constantize), there were some problems with the version of the gem we're using.

Currently, ActiveSupport is required on a very permissive way (>= 2). That's intended to allow you to run rediline on a Rails2 application.

Moreover, we're using ActiveModel for the callbacks. And it requires ActiveSupport 3.0. So for now, there's no dependency to ActiveModel. But you must know that you need your models to behave correctly with it in order to have rediline to work.

Add the following to your Gemfile :

gem "rediline"

Bundle install it and you're done, it's installed.

Your user model should look like the following :

class User < ActiveRecord::Base
    include Redline::User

    rediline :timeline do
        list :egocentric do
            [user]
        end
    end
end

This will create a timeline which will be called "timeline", with one list named "egocentric".
In this list, you must return an array of all the users which will see the event created there.

For exemple, if your users have friends, you could do the following :

class User < ActiveRecord::Base
    include Redline::User

    rediline :timeline do
        list :egocentric do
            [user]
        end
        
        list :public do
            user.friends.all
        end
    end
end

With this, any of your users will have two lists : an "egocentric" one, which will contain all the actions made by this same user.
And a "public" one, which will contain all the actions made by this user's friends.

You can retrieve a list's actions with the each method.

User.first.timeline.limit(10).each(:egocentric) do |action|
    p action.inspect
end

You can potentially trigger events in any kind of model, whether they are linked to an ORM or not.
However, when including Rediline::Object, your model should be compatible with ActiveModel::Callbacks.

Here's what your model could look like :

class Post < ActiveRecord::Base
    include Redline::Object
    
    redline :timeline,
        :user => :owner,
        :verb => :created,
        :when => :after_create
end

An after_create event will be added to this model and triggered every time a new post is created.
By default, we rely on the "user" method. But you can overwrite it to anything else like we do with "owner" here.

You can also use procs to define the values.

class Post < ActiveRecord::Base
    include Redline::Object
    
    redline :timeline,
        :user => lambda {|post| post.owner },
        :verb => :created,
        :when => :after_create
end

By default, we use localhost:6379 as the redis server with the namespace "rediline".
However, you can change that.

Rediline has a redis setter which can be given a string or a Redis object.
This means if you're already using Redis in your app, Rediline can re-use the existing connection.

String: Rediline.redis = 'localhost:6379'
Redis: Rediline.redis = $redis

In a rails app, I have an initializer in config/initializers/rediline.rb where I load config/rediline.yml and set the redis information appropriately.

My rediline.yml file is the following :

development:
    host: localhost
    port: 6379
test:
    host: localhost
    port: 6379

And the initializer :

rediline_config = YAML::load(Rails.root.join('config', 'rediline.yml').read)[Rails.env]
Rediline.redis = Redis.new(
    :host => rediline_config['host'],
    :port => rediline_config['port'],
    :password => rediline_config['password']
)

Want to hack on Rediline?

First clone the repo and run the tests:

git clone git://github.com/dmathieu/rediline.git
cd rediline
bundle install
rake test

If the tests do not pass make sure you have Redis installed correctly.

Once you've made your great commits:

1. Fork Rediline
2. Create a topic branch - git checkout -b my_branch
3. Push to your branch - git push origin my_branch
4. Create an Issue with a link to your branch
5. That's it!