Developing the web app

For this part, you need installed npm. Please refer to npm docs for installation instructions.

Preparing web application

Let's clone a simple web app template:

~ $ git clone
~ $ cd frontend-template
~/frontend-template $ 

Inside you should find:

  • package.json which adds required dependencies
  • webpack.config.js which is needed for the webpack to work
  • index.js which demonstrates how to interact with the real-time cluster

The template web application uses the Fluence frontend SDK. This SDK allows to locate the real-time cluster with the help of the Fluence smart contract, and then send transactions to this cluster.

Let's take a look at index.js:

// the address of the Fluence smart contract on Ethereum
let contractAddress = "0xeFF91455de6D4CF57C141bD8bF819E5f873c1A01";

// the address of the Ethereum node
// MetaMask is used to send transactions if this address is set to `undefined`, 
let ethUrl = "";

// the backend appId as seen in the Fluence smart contract
let appId = "6";


// create a session between the frontend client and the backend application
// the session is used to send transactions to the real-time cluster
fluence.connect(contractAddress, appId, ethUrl).then((s) => {
  console.log("Session created");
  window.session = s;
  helloBtn.disabled = false;


// set a callback on the button click
helloBtn.addEventListener("click", send)

// send a transaction with the name to the real-time cluster and display the response
function send() {
  const username = usernameInput.value.trim();
  let result = session.invoke(username);
  getResultString(result).then(function (str) {
    greetingLbl.innerHTML = str;

Running the web application

Make sure that you have changed the appId variable to the identifier of the deployed backend!

To install dependencies, and compile and run your web application, run:

~/frontend-template $ npm install
~/frontend-template $ npm run start
> [email protected] start /private/tmp/frontend-template
> webpack-dev-server

ℹ 「wds」: Project is running at http://localhost:8080/

Now you can open http://localhost:8080/ in your browser. You should see an input text element and a disabled button, which should become enabled once the session with the backend is initialized.

You can also open the developer console, and check out the Fluence SDK logs:

Connecting web3 to
Session created

You can also interact with the backend application from the developer console:

let result = session.invoke("MyName");
Hello, world! -- MyName