Java Server two-way communication with browser | Simple Websocket example

In this article we will see how Java server (like Tomcat) can have two way communication with browser webpage using websocket API.

You can get history & basic details about websocket on wiki

Example in this article

  • We will create Java server endpoint to listen to websocket connection using javax.websocket.*  API.
  • We will create simple HTML page which will connect to Java server websocket endpoint using simple Javascript.
  • We will deploy this as a war to Tomcat server.
  • We will test exchange of messages both ways between server & browser.

Websocket Java server endpoint

We will create a simple maven web project for this example. We need to add javax.websocket-api  dependency for this example.

Now let’s create a simple endpoint. In this endpoint,

  • On opening of connection, we will start a separate thread which will send messages to browser every 2000 milliseconds.
  • On receiving message from browser, it will print the message in console.

HTML with Javascript Websocket

Now let’s create simple HTML page with Javascript.

  • This page will connect to above Java server websocket endpoint using Javascript Websocket.
  • Every 200 milliseconds, this page will keep sending messages to server.
  • On receiving/sending messages to/from server, it will append the message to HTML to visualize realtime.

Note: ws://  indicates websocket URL & wss://  indicates websocket secure like https. For our example we will use ws:// .

Refer Websocket to get more information about Javascript Websocket object.


To execute this example, we will use Tomcat server & deploy above example in tomcat. Tomcat server does provide support for websocket.

Here is a video which show demo the code, its deployment to Tomcat using eclipse IDE & browser showcasing exchange of two way messages between server endpoint & browser page.

Output of server

Browser console output

Browser output showing exchange of messages.


Complete code can be found on GitHub

Further Reading

You might be interested in this related article.

Create your own video conference web application using Java & JavaScript


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