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

travis Code Climate

Project Tracking


gem install streama


Define Activities

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]


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 (

Setup Actors

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 =>

Setup Indexes

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


Publishing Activity

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}))

Retrieving Activity

To retrieve the activity stream for an actor


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


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


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




Mongoid 4 support added.


Mongoid 3.0 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.


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!