API ของ WebSocket สำหรับการสื่อสารแบบเรียลไทม์

REST APIs are request/response — the server cannot push. For chat, live dashboards, or notifications you need a persistent two-way channel. API Gateway WebSocket APIs provide exactly that.

A WebSocket API has special routes:

• $connect when a client connects
• $disconnect when it leaves
• $default for unmatched messages

Custom routes are chosen by a route selection expression, usually a field in the incoming JSON such as $request.body.action.

The $connect handler receives a unique connectionId. Store it (e.g. in DynamoDB) so you can message that client later.

On disconnect, remove the stored connectionId so you do not try to message a dead client.

To send data back, call the management API with the target connectionId.

To broadcast, loop over all stored connectionIds and post to each. Remove any that return a 410 Gone status — those clients have disconnected.

Attach a Lambda authorizer to the $connect route to validate a token before the connection is accepted, rejecting unauthorized clients up front.

WebSocket connections last up to 2 hours, with a 10-minute idle timeout. Clients should reconnect when dropped, and you should handle stale connectionIds gracefully.

You pay for messages transferred and for connection-minutes, not for idle request count. This makes WebSocket APIs cost-effective for bursty real-time traffic.

Reach for WebSocket APIs when you need:

• Live chat or collaboration
• Real-time dashboards
• Server-initiated notifications

For simple request/response, stick with REST or HTTP APIs.

Test your WebSocket API knowledge.

You learned real-time APIs:

• WebSocket APIs add two-way communication
• $connect, $disconnect, $default plus custom routes
• Store connectionIds and push via postToConnection
• Authorize on $connect; handle stale connections