Solana: How to retry a rpc subscription using web3.js 2.0?

Request RPC subscription with Web3.js 2.0: a step-by-step guide

When working with Long-Lived WebSockets (LLWS) using Web3.js 2.0, you may encounter situations where your connection will be dropped for various reasons, such as network problems or server errors. Reconnecting to the same RPC endpoint after disconnection can be difficult without proper error handling and retry mechanisms. In this article, we will look at how to repeat an RPC subscription using Web3.js 2.0.

Why repeat the subscription?

Before starting to solve the problem, it is important to understand why it is necessary to repeat subscriptions:

• Network Latency: Network congestion or packet loss can cause connection drops or delays.

• Server Errors: Server-side issues such as network errors or timeouts can prevent your subscription from being restored.

Web3.js 2.0 Solution

To retry an RPC subscription using Web3.js 2.0, you need to use the retry method provided by the Web3.js 2.0 API. Here is an example of how to implement it:

import {Client} from 'web3';

const client = new Client();


const wsSubscription = client.getSubscription('your-subscription-endpoint');


// Define a repeat function that will be called if the subscription is not available

function repeat(subscription, repeat count, delay) {

  console.log(Retrying subscription ${subscription.address} ${retryCount} times...);

  

  // Wait the specified delay before asking to restore the connection

  installTimeout(() => {

    subscription.connect().then((connected) => {

      wsSubscription = connected;

      client.getSubscription('your-subscription-endpoint').on('data', (data) => {

        console.log(Received data from ${subscription.address}:, data);

      });

    }).catch((error) => {

      if (retryCount > 0) {

        repeat request (subscription, number of repeat requests - 1, delay);

      } more {

        issue an error;

      }

    });

  }, delay);

}


// Usage example

client.getSubscription('your-subscription-endpoint')

  .then((subscription) => {

    repeat(subscription, 3, 1000); // Repeat the request up to 3 times with a delay of 1 second between requests

  })

  .catch((error) => {

    console.error(error);

  });

Best Practices and Considerations

When implementing this solution:

• Keep re-requests low: Don’t over-rely on re-requests, as excessive re-requests can lead to increased latency and reduced performance.

• Use a delay between re-requests: Implementing a fixed delay ensures that each re-request has enough time to propagate through the call stack and potentially resolve the problem.

• Monitor Subscription Activity

  : Monitor your subscription’s connection status to detect potential problems or network congestion.

By following this tutorial, you’ll be able to implement a robust retry mechanism for Web3.js 2.0 RPC subscriptions using LLWS. This approach will help you overcome common problems and ensure a stable and high-performance web application.

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