MCP Dev Summit Seoul 2026

MCP's current transport model is largely request/response — but production agents need to react to live events without polling. GraphQL subscriptions, delivered over graphql-ws or graphql-sse, offer a battle-tested, widely deployed event streaming primitive that maps cleanly onto MCP's resource notification model. This talk covers the full protocol translation layer needed to wire GraphQL subscriptions into an MCP server as push-based resource updates: how subscription events become MCP notifications, how to map GraphQL variables to MCP resource URIs, and how to handle subscription lifecycle — setup, teardown, and mid-session schema changes. We'll dig into the tradeoffs between WebSocket and SSE transports for different agent deployment environments, covering reconnection strategies, message ordering guarantees, and backpressure handling when an agent falls behind the event stream. Load tested using Grafana k6 against 2,000 concurrent subscriptions running on Apollo Server, this architecture achieves P99 event-to-agent latency under 80ms and sustains throughput that is 4.2× faster than a comparable polling baseline.