Web Sockets in Canvas

The Canvas WebSocket connection is initiated by sending a WebSocket handshake request from a browser's HTTP connection to a server to upgrade the connection.
In the scenario of updating a UI component of a website at frequent intervals (e.g. stock rates or train details), the WebSockets serve as optimal solution where multiple calls to the server can be made by establishing a single connection. This decreases the serving time of the requests.

Steps to Publish and Subscribe to WebSockets:

1. Enable WEB_SOCKET_ENABLED=Y property in the securityconfig property file.

2. Create instance for WebSocketManager in your application class file.

   WebSocketManager webSocketManager=WebSocketManager.getInstance(); 

3. Invoke the publishMessage method to publish the WebSocket from server to client.

   // Input argument : WebSocketPublisherBean instance with properties publisherName, header, message 
   webSocketManager.publishMessage();

   Sample: The following snippet publishes the custom message from WebSocket.
   
   

   package com.intellectdesign.modelhouse.websocket; 
   import com.intellectdesign.canvas.websocket.WebSocketManager;
   import com.intellectdesign.canvas.websocket.WebSocketPublisherBean; 
   import java.util.HashMap;
   import java.util.Map; 
   public class WebSocketMessagePublisher { 
   public static void customPublish(String publisherName,Map header,Map Message){ 
   WebSocketManager webSocketManager;
   webSocketManager = WebSocketManager.getInstance();
   WebSocketPublisherBean webSocketPublisherBean=new WebSocketPublisherBean();
   webSocketPublisherBean.setPublisherName(publisherName); 
   webSocketPublisherBean.setHeader(header);
   webSocketPublisherBean.setMessage(Message);
   webSocketManager.publishMessage(webSocketPublisherBean);
   } 
   public static void main(String[] args) {
   Map headerData=new HashMap();
   headerData.put("Test", "test1");
   Map bodyData=new HashMap();
   bodyData.put("data", "data1");
   WebSocketMessagePublisher.customPublish("monitor",headerData,bodyData);
   }
   }

4. Subscribe with WebSocket channel. For the first time, the connection will be established with namespace ct.websocket.message.received.
   

   ct.MessageBus.subscribe('subscribename','ct.websocket.message.received'); 
   // subscribename => subscriber name 
   // ct.websocket.message.received => namespace and it will be always same 

   Sample: The following snippet subscribe establish & fetch data from web socket connection.

   ct.comm.MessageBus.subscribe('monitor','ct.websocket.message.received',this,function(data)
   {//business logic need to be done herealert('WELCOME TO WEBSOCKET'+data);
   });