In web development, it’s common to have applications that work with local data stored in a client-side database like IndexedDB. However, there are times when you need to synchronize this local data with a remote server for further processing or analysis. Apache Solr is a widely used search platform that provides powerful indexing and querying capabilities. In this blog post, we will explore how to implement data synchronization between IndexedDB and Apache Solr to keep the data in sync.

Prerequisites

Before we begin, make sure you have the following setup:

1. IndexedDB: Ensure you have basic knowledge of setting up and working with IndexedDB in your web application.
2. Apache Solr: Set up an instance of Apache Solr and have a basic understanding of its REST API.

Steps to Implement Data Synchronization

Let’s look at the steps involved in implementing data synchronization between IndexedDB and Apache Solr.

1. Retrieve Data from IndexedDB: Use the IndexedDB API to fetch the local data that needs to be synchronized. Write a function to retrieve the required data from the IndexedDB database.

// Retrieve data from IndexedDB
function getDataFromIndexedDB() {
    const request = indexedDB.open("myDatabase", 1);
    request.onsuccess = function(event) {
        const db = event.target.result;
        const transaction = db.transaction("myObjectStore", "readonly");
        const objectStore = transaction.objectStore("myObjectStore");
        const dataRequest = objectStore.getAll();
        dataRequest.onsuccess = function(event) {
            const data = event.target.result;
            synchronizeDataWithSolr(data);
        };
    };
}

1. Synchronize Data with Apache Solr: Once you have the data from IndexedDB, you need to send it to Apache Solr using its REST API for synchronization. Write a function to send the data to Solr using the fetch API or any AJAX library.

// Synchronize data with Apache Solr
function synchronizeDataWithSolr(data) {
    const solrUrl = "http://localhost:8983/solr/my_core/update/json/docs";
    
    const payload = JSON.stringify(data);
    
    fetch(solrUrl, {
        method: "POST",
        headers: {
            "Content-Type": "application/json"
        },
        body: payload
    })
    .then(response => {
        if (response.ok) {
            console.log("Data synchronized successfully with Apache Solr");
        } else {
            console.error("Error synchronizing data with Apache Solr");
        }
    })
    .catch(error => {
        console.error("Error synchronizing data with Apache Solr", error);
    });
}

1. Trigger Data Synchronization: Now, you need to trigger the data synchronization process at the appropriate time. It can be done when the user performs specific actions or at predefined intervals.

// Trigger data synchronization
function triggerDataSync() {
    // Add your logic to trigger synchronization
    getDataFromIndexedDB();
}

1. Handle Changes in IndexedDB: If your application allows users to modify data stored in IndexedDB, you need to listen for changes and update them accordingly in Apache Solr. Use the IndexedDB onsuccess event to detect changes and trigger data synchronization.

// Listen for changes in IndexedDB and trigger synchronization
function listenForChangesInIndexedDB() {
    const request = indexedDB.open("myDatabase", 1);
    request.onsuccess = function(event) {
        const db = event.target.result;
        const transaction = db.transaction("myObjectStore", "readonly");
        const objectStore = transaction.objectStore("myObjectStore");
        
        objectStore.oncomplete = function(event) {
            triggerDataSync();
        };
    };
}

Conclusion

Data synchronization between IndexedDB and Apache Solr brings the benefits of local data storage and powerful search capabilities together. By following the steps outlined in this blog post, you can implement this synchronization process in your web application. Remember to trigger the synchronization process at the appropriate time and handle changes to keep the data in sync between IndexedDB and Apache Solr.

#IndexedDB #ApacheSolr