Javascript – Abetoo IoT wiki

Introduction. Installation

abetoo — Mon, 26 Jun 2017 09:26:31 +0000

With the Abetoo Javascript library you can send messages to a whatever device in the world from a web page, no matter if your end device is a desktop application, a mobile app or an arduino device.

Simply download the javascript library code and use it in your own webpages.

First steps. Hello World

abetoo — Mon, 26 Jun 2017 09:50:46 +0000

Once you’ve downloaded the last version of the Abetoo Javascript library you’re done to start.

We’re going to build a website which allow us to connect and receive messages.

Open a regular text editor and create a new file called helloworld.html, and copy the following lines,



   Abetoo Library JavaScript Hello World
   Messages Received

let’s go and check it out the source code more deeply,

The most important thing you have to do is to include the abetoo library with the following line, the file abetoo.js has to be on the same folder you are working on.

....

....

Then we can define and launch the connection,

....
   // Define a new Abetoo connection
   var abetoo = Abetoo.getInstance();
   abetoo.init("-7glliYjxdE-H6QudCmEL7g636307126198941784#"+
               "8dd71c893d5502f2b5ae0e5175a8c588a0060474", callback);
....

… and establish a listener for the incoming messages,

function callback(newmessage)
   {
      // Once a new message is received, 
      // append it to the messages received box
      var textelement = document.getElementById('messagesreceived');
      textelement.value += newmessage + "\n";
      textelement.scrollTop = textelement.scrollHeight;
   }

in this particular case, whenever a new message is received, it’s appended to the received messages box.

If you open the generated helloworld.html file with a web browser you’ll see something like that,

You can download the full source code of this example.

To Infinity and Beyond

abetoo — Mon, 26 Jun 2017 10:19:48 +0000

Once you’ve understood the basics, you’re ready to communicate the web app with the world.

We’re going to build a web app that allows us to send and receive messages to/from any other connected devices, even another web app. This web app will also allow us to test the connectivity against remote devices.

If you don’t change the Remote Channel id, every message sent will appear at the abetoo website.

Open a regular text editor and create a new file called messagetesttool.html and copy the following code,



 Abetoo Library JavaScript Test Tool
 
 
 
 Remote Channel Id
 
 Message Content
 
 
 
 
 
 Messages Received

There’s a few changes over the hello world sample code.

We’ve introduced a new function to send messages, whenever the send button is clicked a new message is sent to the remote channel introduced and with the content defined in the textarea with the id messagecontent.

....
 // This function is called whenever the send button is clicked
 function sendMessage()
 {
  var remotechannel = document.getElementById('remotechannel').value;
  var messagecontent = document.getElementById('messagecontent').value;
  var correlationid = "-";
  abetoo.sendMessage(remotechannel, messagecontent, correlationid);
 } 
....

If you want to change the default local Channel id, please modify the abetoo.init function call with your unique channel id.

If you launch the code above with a regular web browser, you’ll see something like that,

This app is very useful not only to communicate with another web app but to be able to test quickly ours desktop/mobile app. You can use it as a remote console test.

You can download the full source code of this example with the following link.

Basic Chat application.

abetoo — Mon, 26 Jun 2017 14:11:46 +0000

With the following application you can communicate two web pages with each other, even guessing that they aren’t at the same location.

Download and open the app zip file, you’ll find two files jschatuser1.html and jschatuser2.html. You can open the files with any web browser, either both locally or in separate computers.

Library reference

abetoo — Mon, 26 Jun 2017 14:30:21 +0000

Constructor (Singleton)

var abetoo = Abetoo.getInstance();

The object is defined as a singleton object, so first at all you have to get the instance.

Methods

init(QueueName, Callback)

Used to establish a connection with the remote server, normally called just after obtain the instance Abetoo object. Once the connection is triggered, the abetoo object takes care about connection lost management and reconnections. You need to pass two parameters.

QueueName, This is an string which represents the local channel id.
Callback, Used to define a function called whenever a new message is received.

bool sendMessage(String DestinationId, String Body, String Correlationid)

Used to send messages to a remote device using it’s channel id

DestinationId, channel id of the remote device you want to send a message.
Body, message as a XML/JSON or as a plain text.
Correlationid, used to keep track about the messages sent/received. If you want to use a challenge/response approach you can associate the challenge sent message with a correlation id, once a message is received you can use its correlation id to identify the associated challenge message.