Overview#
Field teams deploying to remote locations, disaster zones, or communications-denied environments cannot rely on live map tile servers. The Map Offline domain lets operators cache map tiles to cloud storage before a deployment, carry those tiles onto devices, and later synchronise any edits they made while offline, resolving conflicts automatically or flagging them for manual review when connectivity returns.
Key Features#
- Map tile caching for offline use with cloud storage integration
- Offline edit synchronisation with conflict resolution strategies
- Presigned URL generation for client-side tile uploads
- Cache statistics and management for storage optimisation
- Conflict detection and resolution for concurrent offline modifications
- Support for multiple map tile formats and zoom levels
Use Cases#
Relevant sectors include defence, law enforcement, and critical infrastructure response teams.
- Enabling field investigators to access maps in areas without network connectivity
- Synchronising offline map edits when connectivity is restored
- Caching map tiles for specific investigation areas before field deployment
- Managing offline map storage with usage statistics and cleanup
Integration#
The Map Offline domain integrates with cloud storage for tile persistence, the synchronisation engine for conflict resolution, and the map visualisation layer for rendering.
Open Standards#
- Slippy Map Tile Addressing (XYZ/TMS): Tile coordinates are addressed using the de facto web mapping standard of zoom/x/y indices derived from Web Mercator projection, compatible with OpenStreetMap, Mapbox, and all major tile providers.
- GeoJSON (RFC 7946): Offline feature geometry and properties are stored, exchanged, and synchronised as GeoJSON objects, enabling interoperability with any GeoJSON-compliant mapping client.
- Web Mercator Projection (EPSG:3857 / OGC:CRS84): Tile bounding-box calculations use the Gudermannian-based Mercator formulae that define the Web Mercator coordinate reference system, ensuring geometric accuracy across zoom levels.
- CRDT (Conflict-free Replicated Data Types): Offline edit synchronisation is governed by CRDT-inspired principles, including a vector-clock implementation that tracks causality and resolves concurrent modifications deterministically.
- GraphQL (June 2018 Specification): All tile-cache management and offline edit sync operations are exposed through a typed GraphQL API, enabling strongly-typed, introspectable access from any GraphQL client.
- JSON Web Token (RFC 7519) / OAuth 2.0 (RFC 6749): Service-to-service calls for queue submission are authenticated with scoped JWT bearer tokens, and all end-user mutations are protected by an OAuth 2.0 bearer-token permission check.
- SHA-256 (FIPS 180-4): Each tile is fingerprinted with a SHA-256 hash on upload to support deduplication and integrity verification before overwriting cached content.
- S3-Compatible Presigned URLs (AWS S3 REST API): Tile uploads and downloads use the S3-compatible presigned-URL pattern (implemented via Cloudflare R2), allowing clients to transfer tile data directly to object storage without proxying through the application server.
Last Reviewed: 2026-02-05 Last Updated: 2026-04-14