Node Summit 2012

Building an Activity Stream Engine on
Cloud Foundry with Node.js
Hands-on Lab

By Monica Wilkinson

© 2012 VMware, Inc. All rights reserved

Friday, January 27, 12

About Monica Wilkinson Loves the web and data portability.

Developer Advocate @ Cloud Foundry
12 years development experience.
Last 5 years in Social Web
Open Web Standards Advocate
Contact Me: @ciberch
mwilkinson@vmware.com

CONFIDENTIAL
2


Agenda
1.Overview of Cloud Foundry
2.What is Activity Streams ?
3.Building an Activity Stream Engine

CONFIDENTIAL
3


About Cloud Foundry The first Open PaaS

Multi(n) Languages, Frameworks,
Services & Clouds
Open Source

CONFIDENTIAL
4


Getting Started on Cloud Foundry

CONFIDENTIAL
5


STEP 1 - Get a Cloud Foundry Account

 https://my.cloudfoundry.com/signup/NodeSummit

CONFIDENTIAL
6


STEP 2 - Login to Cloud Foundry

•sudo gem
install vmc
•vmc login
<username>

CONFIDENTIAL
7


STEP 3 - Push your code to Cloud Foundry

vmc push

• Detects runtime automatically.
• In addition if you have manifest.yml vmc will read:
• App Name
• App Instances
• Services to bind to App
•Demo

CONFIDENTIAL
8


What is Activity Streams ?

CONFIDENTIAL
9


http://activityStrea.ms
 Activity Streams is a simple open specification used to describe social
actions around the web.
 The goal of Activity Streams is data portability
 Some publishers of Activity Streams: Socialcast, MySpace, Facebook
and G+
 The default format is JSON but Atom is also supported. The JSON
format was added after we saw some initial limitations with JSON
 Core concepts are: Actor, Verb, Object and Target

CONFIDENTIAL
10


Actor -> Monica
Verb -> Pinned(Bookmarked)
Object -> Rosa Parks’ Bio Page
Target -> Female Leaders Board
Source -> Pinterest
Published -> MLK Day 2012



What is an Activity Stream Engine ?
 An activity stream engine allows you to publish events and subscribe to
events.
 Many activity stream engine support aggregation of events via Streams.
 Many activity stream engines support fanning out activities to subscribers.
 Many activity stream engines tailor the stream to the reader providing Key
Stats and Contextual Info. Example: Monica with 1000 followers or Bank
of America established in 1989

CONFIDENTIAL
12


Building an Activity Streams Engine

CONFIDENTIAL
13


What should we use to store Activities ?

Key-Value Column Document Graph

Redis, Cassandra, MongoDB Neo4J
Riak HBase

CONFIDENTIAL
14


Mongo DB schema-less documents are perfect
for Activities

Key-Value Column Document Graph

MongoDB
(so easy)

CONFIDENTIAL
15


About MongoDB

1. No-SQL database development : {

2. Stores JSON-style tools: many,
documents with language_support: superb,
embedded documents

=
agility: high
3. Horizontally scalable },
production: {
4. Full Indexing Support
speed: fast
5. Open Source so great fault_tolerance: true
ORMs and drivers.
scalability: high

CONFIDENTIAL
16


Step 1- Build the persistence Model
var MediaLinkHash = {
        duration: Number,
        height: Number,
        width: Number,
        url: String
    };

    var ActivityObjectHash = {
       id: {type: String},
       image: MediaLinkHash,
       displayName: {type: String},
       summary: {type: String},
       content: {type: String},
       url: {type:String},
       author: {type: ObjectId, ref: 'activityObject'},
       published: {type: Date, default: Date.now},
       updated: {type: Date, default: Date.now},
       objectType: {type: String},
       attachments: [{type: ObjectId, ref: 'activityObject'}],
       upstreamDuplicates: [String],
       downstreamDuplicates: [String]
    };

    var ActivityObjectSchema = new Schema(ActivityObjectHash)
    this.ActivityObject = mongoose.model('activityObject', ActivityObjectSchema);

CONFIDENTIAL
17


Step 1- Persistence Model
    var ActivitySchema = new Schema({
        id: {type: String},
        verb: {type: String},
        url: {type: String},
        title: {type: String},
        content: {type: String},
        icon: MediaLinkHash,
        object: ActivityObjectHash,
        actor: ActivityObjectHash,
        target: {type: ObjectId, ref: 'activityObject'},
        published: { type: Date, default: Date.now},
        updated: { type: Date, default: Date.now},
        inReplyTo: {type: ObjectId, ref: 'activity'}
    });

    this.Activity = mongoose.model('activity', ActivitySchema);

    return this;
};

CONFIDENTIAL
18


Step 2 - Expose helpers for the queries
 The most important is to be able to list the activities in
descending order by published time.
 It is also important to hydrate any objects for which we
have references

 With Mongoose you can do:
 this.getActivityStream = function(n, fx)
{ Activity.find().sort('published',
'descending').limit(n).populate('target').run
(fx);
}
 More at: https://github.com/cloudfoundry-samples/
activity-streams-mongoose

CONFIDENTIAL
19


How do we make our engine faster and more
scalable ?
 Add support for PubSub
 In a PubSub model as soon as an event is published it
gets sent to all the subscribers.
 The Publisher doesn’t know who the subscribers are, it
simply knows where to publish.
 Redis has nice support for Pub Sub http://redis.io/topics/
pubsub

CONFIDENTIAL
20


Exposing the Engine as Service

CONFIDENTIAL
21


Using Socket.io

 Server Side:
• Subscribe to a Stream
• When there is a new event send it to the client as JSON

 Client Side
• Add support to publish activities to the Stream
• Change the client rendering to use ActivityStrea.ms

 Benefits
• Richer messaging
• Activity Syndication

CONFIDENTIAL
22


http://asms.cloudfoundry.com

CONFIDENTIAL
23


Thank You - Questions ?
Cloud Foundry Activity Streams Libraries are at:
https://github.com/organizations/cloudfoundry-samples

http://cloudfoundry.com
Questions: @cloudfoundry - @ciberch or
mwilkinson@vmware.com



Node Summit 2012

Recommended

Recommended

More Related Content

Similar to Node Summit 2012

Similar to Node Summit 2012 (20)

Recently uploaded

Recently uploaded (20)

Node Summit 2012