Offlinesynchronisation

Offlinesynchronisation, or offline synchronization, describes the process of keeping data consistent across multiple devices or systems when network connectivity is intermittent or unavailable. The goal is to allow users to continue creating and editing data offline and to integrate those changes with a central data store when a connection becomes available.

A typical offline synchronization system includes a local data store on each device, a mechanism to track changes made while offline, and a synchronization engine that reconciles differences with a remote source. Changes are often queued and exchanged as deltas or patches. When online, the system transfers pending updates, applies remote changes, and resolves any conflicts that arise between concurrent edits.

Two major approaches to conflict handling are conflict resolution with operational transformation or using conflict-free replicated data types. Operational transformation adjusts operations to preserve intent, while CRDTs enable automatic convergence of replicas. Simpler schemes may use last writer wins or manual user resolution, depending on the data type and application requirements. Synchronization can be bidirectional or unidirectional, and may employ version vectors, timestamps, or hash-based reconciliation to detect divergences.

Typical use cases include mobile and web applications that must function offline, such as note-taking, field data collection, and collaborative editing. Common technologies include offline-first data stores and replication layers, with examples in the database ecosystem that support local storage and server-side synchronization. Security, data integrity, and schema evolution are ongoing considerations in designing robust offline synchronization solutions.