In modern web applications, offline support plays a crucial role in providing a seamless user experience. One common approach to achieve offline support is by using IndexedDB as a client-side database. However, when it comes to synchronizing the data with a server-side system, there can be challenges in handling complex data structures.

Apache Avro is a popular data serialization framework that provides a compact binary format for efficient data storage and transfer. In this blog post, we will explore how to implement data synchronization between IndexedDB and Apache Avro, ensuring seamless data transfer and compatibility.

Setting up IndexedDB

First, let’s initialize IndexedDB in our web application using JavaScript.

let indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;

let request = indexedDB.open('myDatabase', 1);

request.onerror = function(event) {
  // Handle errors
};

request.onupgradeneeded = function(event) {
  let db = event.target.result;
  
  let objectStore = db.createObjectStore('myObjectStore', { keyPath: 'id' });

  // Define objectStore structure
  // objectStore.createIndex('indexName', 'property', { unique: false });
};

request.onsuccess = function(event) {
  let db = event.target.result;

  // Use db for further operations
};

In the above code, we create an IndexedDB database named ‘myDatabase’ and an object store named ‘myObjectStore’. We can define the structure of the object store by creating indexes on properties.

Serializing Data with Apache Avro

Now, let’s focus on serializing and deserializing data using Apache Avro. We will use the avsc library, which provides a JavaScript implementation of Avro.

First, install the avsc library using npm:

npm install avsc

Next, let’s convert our JavaScript objects to Avro-compatible Binary objects.

const avro = require('avsc');

// Define Avro schema
const schema = {...};

// Create Avro type from the schema
const type = avro.parse(schema);

// Serialize JavaScript object to Avro binary
const avroBinary = type.toBuffer(jsObject);

// Deserialize Avro binary to JavaScript object
const deserializedObject = type.fromBuffer(avroBinary);

In the code snippet above, we define an Avro schema and create a corresponding Avro type using the avsc library. We then serialize the JavaScript object to Avro binary using toBuffer method and deserialize Avro binary back to JavaScript object using fromBuffer method.

Synchronizing Data

Now, let’s bring it all together to synchronize data between IndexedDB and Apache Avro.

const avro = require('avsc');

// Initialize IndexedDB and Apache Avro

...

// Retrieve data from IndexedDB
let transaction = db.transaction('myObjectStore', 'readonly');
let objectStore = transaction.objectStore('myObjectStore');
let request = objectStore.getAll();

request.onsuccess = function(event) {
  let data = event.target.result;

  // Serialize data to Avro binary
  let type = avro.parse(schema);
  let avroBinary = data.map(record => type.toBuffer(record));

  // Synchronize data with server-side system using avroBinary
  // ...

  // Update data in IndexedDB
  let updateTransaction = db.transaction('myObjectStore', 'readwrite');
  let updateObjectStore = updateTransaction.objectStore('myObjectStore');
  
  data.forEach((record, index) => {
    record.updatedProperty = 'Updated';
    updateObjectStore.put(record);
  });
};

In the above code snippet, we retrieve data from IndexedDB and serialize it to Avro binary using the Avro schema and toBuffer method. We can then synchronize the data with the server-side system using the avroBinary values. After that, we update the data in IndexedDB as needed.

By implementing this data synchronization between IndexedDB and Apache Avro, you can ensure that your web application seamlessly works offline and keeps the data consistent with the server-side system.

#dataSynchronization #IndexedDB #ApacheAvro