In this blog post, we will explore how to implement real-time logging with Azure Event Hubs in a Node.js application. Azure Event Hubs is a scalable and highly available event streaming platform that enables you to build real-time applications and process large amounts of data in real-time.

Prerequisites

Before getting started, make sure you have the following:

• Node.js installed on your machine
• An Azure subscription
• An Azure Event Hubs namespace and Event Hub created

Setting up the Node.js application

To begin, let’s set up a basic Node.js application. Create a new directory for your project and navigate to it using the terminal.

npm init -y

This command initializes a new Node.js project with default settings.

Install the required package for connecting to Azure Event Hubs:

npm install @azure/event-hubs

This package provides a client library for interacting with Azure Event Hubs from Node.js.

Sending real-time logs to Azure Event Hubs

Now, let’s implement the code to send real-time logs to Azure Event Hubs.

First, import the necessary modules and instantiate an EventHubProducerClient:

const { EventHubProducerClient } = require("@azure/event-hubs");

const connectionString = "YOUR_EVENT_HUBS_CONNECTION_STRING";
const eventHubName = "YOUR_EVENT_HUB_NAME";

async function sendLogs() {
  const producerClient = new EventHubProducerClient(connectionString, eventHubName);

  // Your code to send logs

  await producerClient.close();
}

sendLogs();

Replace YOUR_EVENT_HUBS_CONNECTION_STRING and YOUR_EVENT_HUB_NAME with your actual Event Hubs connection string and Event Hub name.

To send logs, use the sendBatch method of the EventHubProducerClient:

const logs = ["Log 1", "Log 2", "Log 3"];

async function sendLogs() {
  // ...

  const batchOptions = {
    partitionKey: "YOUR_PARTITION_KEY"
  };

  const batch = await producerClient.createBatch(batchOptions);

  for (const log of logs) {
    if (!batch.tryAdd({ body: log })) {
      await producerClient.sendBatch(batch);
      batch.clear();

      if (!batch.tryAdd({ body: log })) {
        throw new Error(`Unable to add log ${log}`);
      }
    }
  }

  await producerClient.sendBatch(batch);

  // ...
}

sendLogs();

Replace YOUR_PARTITION_KEY with a value to determine which partition to send the logs to.

Receiving real-time logs from Azure Event Hubs

To receive the logs in real-time, we need to create a consumer client.

First, import the necessary modules and instantiate an EventHubConsumerClient:

const {
  EventHubConsumerClient,
  earliestEventPosition,
  latestEventPosition,
} = require("@azure/event-hubs");

async function receiveLogs() {
  const consumerGroup = "$Default";
  const consumerClient = new EventHubConsumerClient(consumerGroup, connectionString, eventHubName);

  // Your code to receive logs

  await consumerClient.close();
}

receiveLogs();

Replace YOUR_EVENT_HUBS_CONNECTION_STRING and YOUR_EVENT_HUB_NAME with your actual Event Hubs connection string and Event Hub name.

To receive logs, use the subscribe method of the EventHubConsumerClient:

async function receiveLogs() {
  // ...

  const subscription = consumerClient.subscribe({
    processEvents: async (events, context) => {
      for (const event of events) {
        console.log(event.body);
      }

      await context.updateCheckpoint(events[events.length - 1]);
    },
    processError: async (error, context) => {
      console.error(error);
    }
  });

  // ...
}

receiveLogs();

This code will continuously receive and log the events from the Event Hub. You can perform any custom logic on the received logs within the processEvents function.

Conclusion

In this tutorial, we learned how to implement real-time logging with Azure Event Hubs in a Node.js application. We covered how to send logs to Azure Event Hubs and how to receive logs in real-time using the Event Hub client libraries.

By leveraging the power of Azure Event Hubs, you can build scalable and real-time logging solutions for your Node.js applications. Start exploring Azure Event Hubs and unleash the full potential of real-time event streaming.

#azure #logging