PB2 is a serverless framework (node.js server + client library) for building collaborative apps.
In this context, serverless means
- building an application without doing any coding on the server side and
- using the same server instance for different client applications (as a service)
PB2 is based on socket.io and to communicate, you have to use certain kind of messages (see below).
With PB2, you can do two things:
- Send JSON messages to the server
- Receive JSON messages from the server
(1) Connecting to the server
First, include socket.io and pb2_client.js into your HTML:
<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>
<script src="pb2_client.js"></script>PB2 Client is available here: https://raw.githubusercontent.com/OAlm/pb2/master/static/pb2_client.js
In javascript, you have to give an unique app_id for your app and connect to the server.
In below, we connect to a server https://pb2.mydomain.com with app_id my_first_app_123:
const pb2 = new PB2('https://pb2.mydomain.com/', 'my_first_app_123');(in Socket.io terms, your app will connect to a room my_first_app_123)
(2) Sending messages
With current PB2 setup, you can send only JSON messages. To send messages, construct a javascript object, with the value you want. In the below example, we will generate the following JSON object and send it to the server.
{
hello: 'world'
}const msg = {};
msg.hello = 'world';
pb2.sendJson(msg);(3) Receiving messages
In order to receive messages, the following javascript code can be used:
pb2.setReceiver(function(data) {
console.log('socket.on message received: '+data);
});The socket will receive any messages send to the server with the app_id. Full chat client example is available here: https://github.com/OAlm/pb2/tree/master/static/chat
The first version of the PB was originally a student project for monitoring autonomous vehicle data in Sohjoa-project, later extended to serve as a general purpose server framework.
References