Vaadin Flow and Distributed Session Stores: State Synchronization Consistency

Server-Side State Persistence

Vaadin Flow maintains a server-side component tree that mirrors the browser DOM. In high-availability environments, this state is often offloaded to a distributed session store to allow for seamless failover across multiple server nodes.

Interoperability Constraints

When the Java server state is serialized and stored externally, any discrepancy between the serialized state and the active Client-Side Engine in the browser can lead to synchronization failures. This is particularly critical when the communication protocol relies on specific component IDs and session identifiers to map JSON payloads to the correct DOM elements.

Given the reliance on a unique session ID and the Atmosphere-based Push mechanism, it is unclear how the framework ensures atomic state recovery when a session is migrated between nodes during an active WebSocket connection.

• How does Vaadin Flow reconcile the client-side component tree if the recovered server-side state lacks the most recent asynchronous updates?
• What mechanism prevents state divergence when a distributed session store recovers a state that is slightly behind the client's current DOM version?