Using websockets and android to control robots in realtime

Using WebSockets and Android
to control robots in real-time
Sudar Muthu (@sudarmuthu)
http://hardwarefun.com
http://github.com/sudar

Who am I?

Research Engineer by profession
Create robots as hobby
Uses an Android phone
Why not combine both of them?
Has spoken in 6+ hasgeek events 


Android and Arduino

There are at least half dozen ways to do it and I am not
going to talk about each of them.

http://sudarmuthu.com/blog/building-robots-using-
arduino-and-android-at-droidcon


So today…

WebSockets in Android
How to use it to control robots


Why hardware for a software hacker?

Fun!


Let’s start with a demo

Demo
http://hardwarefun.com/projects/asimijs


Participate in the demo 

Visit
http://hardwarefun.com:3000


Control the bot at stage

#asimijs @hardwarefun

Now let’s see how I built it


What is WebSockets?

Full-duplex over a single TCP connection
Provides push support
Designed to work inside browsers
Works on port 80


WebSockets vs HTTP


HTTP (Pull)

Is there an update?

No

Is there an update?

No

Is there an update?

Yes


WebSockets (Push)

Tell me when you have an update

Ok

Here is the update


Why use WebSockets in Android

Firewall friendly
No need to reinvent protocol
Real-time communication
Easy to setup server


Remember, I am not talking about
using WebSockets inside an
Android browser


WebSocket implementation for
Android

There are lot of options, but I choose Socket.IO
implementation by Kaushik Dutta (Rom Manager fame)

https://github.com/koush/android-websockets


Why Socket.IO?

You should have attended jsFoo
;)


Why Socket.IO

Additional features on top of WebSockets
Node.js based server
Has support for maximum no: of browsers
Has clients in lot of languages


and ….

I had the server already written



Let’s see some code


In Android, create a socket
client = new SocketIOClient(URI.create(
”http://hardwarefun.com:3000"),new SocketIOClient.Handler() {
@Override
public void onConnect() {
Log.d(TAG, "Connected!");
}

@Override
public void on(String event, JSONArray arguments) {
Log.d(TAG, "Got event);
}

@Override
public void onDisconnect(int code, String reason) {
Log.d(TAG, "Disconnected!);
}
});

Send data through socket

client.connect();

JSONArray arguments = new JSONArray();
arguments.put("first argument");
JSONObject second = new JSONObject();
second.put("dictionary", true);
arguments.put(second)
client.emit("hello", arguments);

client.disconnect();

In node.js side

var io = require('socket.io').listen(80);

io.sockets.on('connection', function (socket) {
socket.emit('news', { hello: 'world' });
socket.on(’my other event', function (data) {
console.log(data);
});
});


Checkout the full source code
at


So…

How the demo worked?


Node.js Server

Android Client

Admin page

Web Socket User page Asimi (Bot)
User page
ADK User page


Links

AsimiJS – The demo that I showed initially
Android websockets - https://github.com/koush/android-
websockets
Getting started with hardware programming
http://hardwarefun.com/tutorials/getting-started-with-hardware-
programming
Getting started with Arduino
http://hardwarefun.com/tutorials/getting-started-with-arduino-
and-avr
Android and Arduino - http://sudarmuthu.com/blog/building-
robots-using-arduino-and-android-at-droidcon
Arduino Workshop - http://hardwarefun.com/arduino-workshop

Thank you
Sudar Muthu
http://github.com/sudar

Using websockets and android to control robots in realtime

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Using websockets and android to control robots in realtime