1. Streaming Geo
Coordinates from
MongoDB to your
iPhone App with
PubNub using
WebSocket SDK!
by Stephen Blum

2. Not long ago we partnered with a high-
standards online engineering broker (an
online listing service where you can post
engineering projects). The partnership
involved joint PR and blogging, however a
new opportunity/idea was presented. This
particular idea stemmed from a
commission listed on the broker’s website
which listed requirements for building an
integrated Real-time Map Service. We took
the opportunity and built a Ruby GEM with
a sprinkle of documentation and HTML5.
Continue through the slides for a quick start
guide to build an integrated real-time map
service.

3. For those of you who need a quick mini-guide to getting your MongoDB installed and running with
data sync streaming directly to your mobile app, you can follow this guide:
MongoDB Pipe GitHub Repository. It will show you how to download/install MongoDB and the
MongoPipe GEM.
Real-time Data Stream of Geo Coordinates
Lat/Long from MongoDB replicated to your iPhone App
The commission at the online workplace was posted as a $3,025 bounty. Rather than taking the
commission for ourselves, which involves building and delivering the solution in a private exchange,
we instead reviewed the specifications and requirements and we developed an open source
implementation that you can download and run for your live app today! MIT License, so you can use
this however you desire. We even created a GEM for you and made it easy to get started:
gem install mongopipe

4. Downloading the GEM is the first step in the process and next we’ll walk you through more details.
Actually now may be the time for you to watch the short video (next slide), so feel free to jump into
that now if you want a very brief demonstration and usage covering these points:
1. Installing the Ruby gem and
2. Executing the commands to setup MongoDB and
3. Running the Pipe Daemon.
4. Launching the Map Viewer.
5. Finally inserting lat/long coords into MongoDB.
6. Result is live-animated points on a map displayed on the iPhone.
The video will show usage of the MongoPubNubPipe gem. Source code is available via GitHub if you
want to see everything - MongoDB Pipe GitHub Repository

5. MongoPubNubPipe::Connect.new(...)
MongoDB Geo Coordinates
This becomes the new interface that is available with mongopipe gem:
Usage of MongoPubNubPipe is available in later slides.

6. The video demonstrates an implementation of the connection between MongoDB and a mobile
device (an iPhone in this case). This application code and gem library will provide you a way to easily
add a live always-on map connection which allows you to send lat/long signals directly to the device
displaying the map with the specific Lat/Long DB written into MongoDB. This will cause the device
to draw an animated dot onto the screen of the device in real-time.
The dot that animates is triggered by simply writing to your MongoDB collection directly either
through the mongo console or through your RoR/Ruby Server Code. For example here is a MongoDB
Console Command that will cause a DB write, creating a Document, which then triggers the sync
with the consumer iPhone device that is rendering the map in real-time.
db.collection_name.insert({ latlon : [ 1.5, 2.0 ] })

7. gem install mongopipe
Once you’ve written a Lat/Long coordinate into MongoDB collection, the process begins instantly
synchronizing with any connected iPhone. We where able to include several feature requests and
here follows the requirements:
When a new Lat/Lon document is inserted into MongoDB, stream the Lat/Lon data to a mobile
device is push data.
Use a Ruby or Node.JS Service to stream the data out of MongoDB as it is written in real-time.
Simple enough, yes, though it requires moving pieces. We simplified the process and built two
modules: one in Ruby and one in HTML5. We’ll walk through the methods for getting you started and how
to hook into the stream on your iPhone App. You can fast-track the tutorial and go strait to the
GitHub Repository or gem install mongopipe package for ruby.
GitHub Repository
MongoDB Pipe GitHub Repository

8. How it Works
MongoPipe is a new tool powered
by PubNub that streams your
MongoDB Documents from your
MongoDB Collection directly to your
iPhone App in less than 0.25 seconds
(real-time) using the PubNub Real-time
Network. Your iPhone app opens an
always-on TCP Socket Connection to
PubNub while a dispatch process runs
on your MongoDB server via Tailable
Cursors to catch inserted documents.
The data is streamed and brokered via
PubNub Network directly to your
iPhone App in real-time.

9. mongod
require 'rubygems'
require 'mongopipe'
## ------------------------------------------------------
## Pipe MongoDB for Inserts
## ------------------------------------------------------
MongoPubNubPipe::Connect.new(
:puts_usage => true,
:publish_key => 'demo',
:subscribe_key => 'demo',
:db => 'test',
:collection => 'cap_collection',
:callback => lambda{ |doc|
## Optional Callback Called on Doc Insert
## Remove :callback if you don't need it.
puts(doc)
}
).pipe()
MongoDB Tailable Cursors
The ruby GEM mongopipe utilizes the tailable
cursor interface provided by MongoDB
Core. Document Data is then piped directly
through the PubNub Network which uses a
direct broadcast synchronization socket
with the mobile app.
Next we’ll show you what the process is to
get the mongopipe running on your Ruby
Server.
Make sure MongoDB is running
Next open a text editor and copy/paste the following
monogopipe example.
Save this to a file pipe.rb for example then execute it.
Ruby pipe.rb

10. Step 1: Open Your Browser to Show PubNub Pipe Console
This will connect directly to MongoDB and print usage guide on next steps. The video covers only a
demonstration of this process. Here is a sample output of what may be provided via the puts(doc) output:
> Open http://www.pubnub.com/console?channel=test.cap_collection
Step 2: Open Demo Map on Your Phone
> Open http://goo.gl/HAqAv#test.cap_collection
Step 3: Insert Test Data
> ./mongo
> Use test
> db.cap_collection.insert({ latlon : [ 1.5, 2.0 ] })

11. Remaining Details
This blog entry was intended to give you a quick
skim over the details on how the mongopipe ruby
gem works and what is involved in coordinating
the embeddable mobile HTML5 animated map.
If you have any more questions please
tweet @PubNub directly.
You may be curious about the connectivity
mechanism between your iPhone App and your
MongoDB Sever. Checkout the PubNub
WebSocket Reference below to see the
transport mechanism utilized.
Thank you for reading!

12. PubNub WebSocket Reference
The MongoDB Pipe uses the PubNub Network WebSocket interface which provides an always-on
socket connection to your iPhone app. The PubNub Network WebSocket acts as a broadcast
receiver and syncs directly to your mobile device in real-time from your MongoDB server via
MongoPipe.
Following is an example of how the Map app implements the socket:
// Create Socket Connection
var socket = new WebSocket(
'wss://pubsub.pubnub.com/PUBLISH_KEY/SUBSCRIBE_KEY/CHANNEL'
);
// Set Message Receiver Function
socket.onmessage = receiver;
// Receiver Function Prints Data Result
function receiver(evt) { console.log(evt.data); }