session-storage-backends

SSE event management for reconnection resumability uses monotonic IDs to track event sequence, applies configurable retention policies to limit history size, and executes scheduled cleanup to remove expired events from your chosen storage backend.

You configure a custom session storage backend in an MCP server by wiring backend-specific implementations through McpServer::builder().with_session_storage(...), passing a configured instance that implements the SessionStorage trait API.

MCP session storage works across multiple deployment nodes when configured with PostgreSQL or DynamoDB backends, which provide the durable shared state required for multi-node SSE reconnection support and distributed session persistence.

The limitation of using InMemory storage for MCP sessions is the lack of durability across server restarts or crashes, making it unsuitable for multi-node deployments or production environments requiring persistent SSE event history and reconnection resumability.

SSE event management handles reconnection resumability in MCP by using monotonic IDs to track event sequences, applying event retention policies to preserve history, and executing cleanup routines to manage storage capacity across InMemory, SQLite, PostgreSQL, and DynamoDB backends.