WebSocket Scaling

WebSocket RPC turns each client into a long-lived resource consumer. Capacity planning must account for open connections, subscriptions per connection, message fanout, heartbeat traffic, and reconnect storms.

Concern	Gateway policy	Client policy
Load balancing	Use sticky sessions when upstream subscription state is in-memory	Reconnect and resubscribe after disconnect
Connection count	Per-key and per-IP concurrent connection limits	Share connections inside one app process
Subscription count	Method-specific caps for logs, blocks, objects, or accounts	Subscribe narrowly and unsubscribe when unused
Heartbeats	Idle timeout plus ping/pong or app-level heartbeat	Detect dead connections before sending critical work
Reconnect storms	Jittered retry and admission limits	Exponential backoff with jitter

Ethereum clients commonly use WebSocket for eth_subscribe over port 8546 (Geth RPC). Solana exposes WebSocket methods such as logsSubscribe and account subscriptions (Solana WebSocket). Sui exposes subscription-oriented services, including the gRPC SubscriptionService in its fullnode protocol surface (Sui Full Node gRPC methods).

const reconnectDelayMs = Math.min(30_000, 500 * 2 ** attempt) * (0.5 + Math.random());

:::warning Streaming is not indexing by itself Subscriptions can drop, reconnect, or miss messages during failover. Persist cursors and reconcile with polling or checkpoint reads for durable indexers. :::

For durable pipelines, combine WebSocket or gRPC streams with /developer/indexer-architecture.