Build counters, rooms and reservations that keep a consistent shared state. Durable Objects give each named entity a stable coordination point, serialized execution and its own SQLite-backed storage.
The course contains seven guided labs and one independent reservation-repair challenge. You move from named objects and persisted activity to concurrency, alarms and WebSocket behavior.
What You Will Learn
- Route stable names to independent objects
- Persist and retrieve room activity
- Coordinate concurrent reservations without overbooking
- Schedule expiry with object alarms
- Broadcast room updates over WebSockets
- Restore connection context after object reconstruction
- Diagnose a cross-room identity leak
- Repair an overbooked workshop while preserving valid bookings and totals
Who This Course Is For
Workers developers who want to coordinate stateful applications and live clients.
Prerequisites: Complete Workers foundations, Connect LabEx to Your Cloudflare Account and the basic SQL keys, constraints and queries introduced in D1 D01–D02.
Learning environment: Each lab starts in a fresh LabEx VM using your own independently authorized account. You create uniquely named Workers and SQLite-backed object namespaces, then inspect runtime and Dashboard evidence. Bounded synthetic exercises use Workers Free and count toward shared allowances; no purchased domain is required.
Frequently Asked Questions
How is a Durable Object different from an ordinary Worker?
A Worker can route a request, while one named object owns the coordination point and persistent state for an entity such as a room. Names and routing therefore affect isolation.
Will I test concurrent behavior?
Yes. The reservation labs check capacity and durable totals under concurrent requests. Correctness depends on the invariant, not which request happens to arrive first.
Does a disconnected WebSocket mean its state is lost?
The course distinguishes a client connection from object-owned state and restores connection context after reconstruction. You inspect the resulting behavior rather than assuming what an idle period proves.
How do I finish an exercise?
Delete only your disposable Workers and related namespaces, confirm removal while authorized and log out. Preserve unrelated applications and account resources.
