Streama is a simple Ruby activity stream gem for use with the Mongoid ODM framework.

It works by posting to and querying from a firehose of individual activity items.

Currently Streama uses a Fan Out On Read approach. This is great for single instance databases, however if you plan on Sharding then please be aware that it'll hit every shard when querying. I plan on changing the schema soon so that it Fans Out On Write with bucketing.

Data Modeling Examples from the real world

• Streama Google Group
• Code Climate
• Website Demo

gem install streama

Create an Activity model and define the activities and the fields you would like to cache within the activity.

An activity consists of an actor, a verb, an object, and a target.

class Activity
  include Streama::Activity

  activity :new_photo do
    actor :user, :cache => [:full_name]
    object :photo, :cache => [:subject, :comment]
    target_object :album, :cache => [:title]
  end

end

The activity verb is implied from the activity name, in the above example the verb is :new_photo

The object may be the entity performing the activity, or the entity on which the activity was performed. e.g John(actor) shared a video(object)

The target is the object that the verb is enacted on. e.g. Geraldine(actor) posted a photo(object) to her album(target)

This is based on the Activity Streams 1.0 specification (http://activitystrea.ms)

Include the Actor module in a class and override the default followers method.

class User
	include Mongoid::Document
	include Streama::Actor

	field :full_name, :type => String

	def followers
		User.excludes(:id => self.id).all
	end
end

Create the indexes for the Activities collection. You can do so by calling the create_indexes method.

Activity.create_indexes

In your controller or background worker:

current_user.publish_activity(:new_photo, :object => @photo, :target_object => @album)

This will publish the activity to the mongoid objects returned by the #followers method in the Actor.

To send your activity to different receievers, pass in an additional :receivers parameter.

current_user.publish_activity(:new_photo, :object => @photo, :target_object => @album, :receivers => :friends) # calls friends method

current_user.publish_activity(:new_photo, :object => @photo, :target_object => @album, :receivers => current_user.find(:all, :conditions => {:group_id => mygroup}))

To retrieve the activity stream for an actor

current_user.activity_stream

To retrieve the activity stream and filter by activity type

current_user.activity_stream(:type => :activity_verb)

To retrieve all activities published by an actor

current_user.published_activities

To retrieve all activities published by an actor and filtered by activity type

current_user.published_activities(:type => :activity_verb)

If you need to return the instance of an :actor, :object or :target_object from an activity call the Activity#load_instance method

activity.load_instance(:actor)

You can also refresh the cached activity data by calling the Activity#refresh_data method

activity.refresh_data

Mongoid 4 support added.

Mongoid 3.0 support added.

The Activity "target" field was renamed to "target_object". If you are upgrading from a previous version of Streama you will need to rename the field in existing documents.

http://www.mongodb.org/display/DOCS/Updating#Updating-%24rename

Once you've made your great commits

1. Fork
2. Create a topic branch - git checkout -b my_branch
3. Push to your branch - git push origin my_branch
4. Create a Pull Request from your branch
5. That's it!