Best way to synchronize local HTML5 DB (WebSQL Storage, SQLite) with a server (2-way sync)

javascript

synchronization

websql-storage

sqlite

byAlex Kataev·Jan 30, 2025

The quickest route to synchronize a local HTML5 WebSQL with a server is by utilizing timestamps/revision numbers for change tracking and establishing a conflict resolution strategy. You can execute optimal synchronization in three simple steps:

Track changes with revision numbers or timestamps in both local and server-side databases.
Trigger syncs at regular intervals or upon specific event occurrences.
Compare data across databases, resolve conflicts, and exchange updates appropriately.

Here's pseudo code with jokes in comments for performing bi-directional sync:

function syncDatabases() {  //Here is where the magic happens... or the syncing, I guess.

  //Step 1: Just get me those changes, alright?
  getLocalChanges().then(sendToServer) // "Dear Server, these are my secrets. Please don't spill them."
    .then(applyServerChangesToLocalDB); // "Thanks Server for your secrets. They're safe with me."

  getServerChanges().then(applyServerChangesToLocalDB) // "Face to face again. It feels like only milliseconds ago we last spoke."
    .then(getLocalChangesAfter).then(sendToServer); // Rinse and repeat.
}

As efficiently shown, an ideal solution should:

Streamline the process of identifying, sending and applying changes.
Assure integrity of data through comprehensive error handling capabilities.
Lean towards IndexedDB if potential-proofing is on the cards. Remember, deprecation haunts WebSQL!

Decoding the synchronization libraries

If you're seeking an off-the-shelf tool to help with synchronization, below are some libraries to consider:

WebSqlSync: This JavaScript library facilitates 2-way sync between the client and server databases. WebSqlSync even handles table and trigger auto-creation, to ease your worries.
QuickConnect: This tool is a crackerjack in native SQLite synchronization on iOS and Android platforms.
PersistenceJS: This asynchronous JavaScript ORM comes handy when there's a need for smooth data model interchange between the browser and server.
Impel.inTouch: If you already use the Mootools framework, look no further. This tool provides a lean approach to synchronization.
Sencha.io Sync Service: A bespoke service for those already using the Sencha Touch framework.

Pick the supplementing tool that suits your existing stack or, if you're not chained to a framework, consider WebSqlSync for independence and functionality.

Sailing through advanced synchronization waters

Real-world database synchronization isn't always a walk in the park. So, let's address some commonly encountered complexities:

Conflict resolution and Connectivity chaos

Maintain a logical strategy for conflict resolution to handle concurrent updates.
When connectivity's on a vacation, queue local changes for a later rendezvous with the server.

Enforcing Security measures

Synchronization isn't complete without contemplating about security considerations:

Stick to https protocol for secure data transfers.
Implement a robust authentication and authorization mechanism to keep data stalkers at bay.

Tackling updates and migrations

When it's time for hefty updates or migrations, good planning pays off:

Have your synchronization protocol adapt to database schema updates, while maintaining backward compatibility.
When your databases need a major revamp, ensure you have a good migration path for them to stay in sync.

explain-codes / Javascript / Best way to synchronize local HTML5 DB (WebSQL Storage, SQLite) with a server (2-way sync)

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