Solana: How do I retry an RPC subscription using web3.js 2.0?

Retrying an RPC Subscription with Web3.js 2.0

When using Web3.js 2.0, establishing a long-lived WebSocket connection can be a bit more difficult than in previous versions of the library. A common issue is reconnecting after a disconnect, which can result in lost transactions or sending duplicate data.

In this article, we’ll explore how to retry an RPC subscription using Web3.js 2.0.

Why Retry?

Remote Procedure Call (RPC) subscriptions allow you to execute blockchain functions remotely without worrying about establishing a direct connection between client and server. However, as with any asynchronous operation, there is always the possibility of a disconnect or error.

If a disconnect occurs, your application may lose its position in the blockchain transactions that are being processed. As a result, all pending transactions may be resubmitted multiple times, resulting in wasted gas and lost value.

Solution: Retry Mechanism

To solve this problem, we implemented a retry mechanism using the built-in error handling features of Web3.js 2.0. Our solution uses the retry function from the web3 package to automatically reconnect when necessary.

Here is an example of how you can change your code to include retry:

const web3 = require('web3');
const { retry } = require('web3');
// Replace with the URL of your Web3.js provider
const provider = new web3.providers.HttpProvider("
// Initialize the connection to the blockchain network
async function connectToBlockchain() {
const chainId = await web3.eth.getChainId();
console.log(Connected to blockchain ${chainId}...);
// Create a new Web3 instance with your provider
const web3Instance = new web3(provider);
return web3Instance;
}
// Set up an RPC subscription
async function EstablishRpcSubscription() {
try {
const wsSubscription = await createWeb3RpcSubscription(
'0xYourPublicKey', // Your RPC endpoint
{ network: 'mainnet' } // Specify the blockchain network (e.g. mainnet, testnet)
);
console.log(RPC subscription set up successfully!);
return wsSubscription;
} catch (error) {
if (error.message.includes('Disconnected')) {
// Retry the connection after disconnection
retry(error, 5);
}
console.error('Error setting up RPC subscription:', error);
throw error;
}
}
// Main entry point for your application
async function main() {
const web3Instance = await connectToBlockchain();
const wsSubscription = await establishRpcSubscription();
// Handle any errors that occur during the connection
try {
console.log('WebSocket connection established.');
} catch (error) {
throw error;
}
return wsSubscription;
}

Here’s how it works:

• The connectToBlockchain function sets up a new Web3 instance with your provider.

• The establishRpcSubscription function attempts to create an RPC subscription using the established connection.

• If the subscription is successfully created, it returns the newly created WebSocket object (wsSubscription).

• Otherwise, if the connection is interrupted, after a short delay (5 seconds), the retry mechanism is triggered using the Web3 “Retry” function.

• When the retries are exhausted or successful, the original error is triggered again.

Conclusion:

By implementing this retry mechanism, you can ensure that your Web3.js applications remain responsive and efficient even in the event of interruptions or errors in blockchain transactions. This approach also helps minimize gas waste and loss of value due to repeated retries.