Real-Time APIs · Real-Time Transports
Emerging Options: HTTP/3, WebTransport and Managed Services
What's new and when to use a managed real-time platform.
WebTransport (over HTTP/3/QUIC) offers multiple streams and unreliable datagrams with low latency, without TCP head-of-line blocking — useful for games, media and high-frequency updates; browser support is growing but not universal, so keep fallbacks. Managed real-time services (Ably, Pusher, PubNub, AWS AppSync/API Gateway WebSockets, Azure Web PubSub, Cloudflare Durable Objects, Supabase Realtime) handle connection scaling, presence and global edge delivery.
Build vs buy vs new protocols
| Criterion | Self-hosted WebSockets | Managed real-time service | WebTransport |
|---|---|---|---|
| Ops effort | High at scale | Low | High (new stack) |
| Global latency | Depends on deployment | Edge networks | Low (QUIC) |
| Features | Build yourself | Presence, history, auth hooks | Streams + datagrams |
| Cost | Infra | Per message/connection | Infra |
| Maturity | High | High | Emerging |
// WebTransport (browser, where supported)
const wt = new WebTransport("https://rt.example.com:4433/game");
await wt.ready;
const writer = wt.datagrams.writable.getWriter();
writer.write(new Uint8Array([1, 2, 3])); // unreliable, unordered: good for position updates
Common pitfalls
- Adopting WebTransport without fallbacks.
- Underestimating the cost of building presence/history/scaling yourself.
- Vendor lock-in without an abstraction layer.
Key points
- WebTransport for low-latency streams/datagrams
- Managed services save ops at scale
- Keep fallbacks and abstractions
Further reading: MDN: WebTransport API
Practice questions
What advantage do WebTransport datagrams offer for games?
Answer
Unreliable, unordered delivery means stale position updates aren't retransmitted or block newer ones, minimizing latency.
When is a managed real-time service worth it?
Answer
When you need global scale, presence, message history and connection management without a team dedicated to operating WebSocket infrastructure.
Open in the app to mark lessons complete, take notes and track your progress.