Sub-servers and Protocols

One Swoole server listens on one port. A sub-server adds a listener on another port, so one process can serve HTTP on one port and WebSocket on another. Sub-servers are useful when clients need different protocols on different ports, such as a website and a real-time channel.

How Sub-servers Work

createSubServer() returns a copy of the parent server that is configured as a sub-server. The parent starts every sub-server when the parent calls listen(). A sub-server does not open its port on its own.

The optional argument sets protocol flags. Combine them with |:

Constant	Swoole setting
Protocol::HTTP	open_http_protocol
Protocol::HTTP2	open_http2_protocol
Protocol::WEBSOCKET	open_websocket_protocol
Protocol::MQTT	open_mqtt_protocol

Example

use Windwalker\Reactor\Protocol;
use Windwalker\Reactor\Swoole\SwooleServer;

$server = new SwooleServer();

$websocket = $server->createSubServer(
    Protocol::WEBSOCKET,
);

$websocket->onMessage(function ($event) {
    // Handle WebSocket frames on port 9502.
});

$websocket->listen('0.0.0.0', 9502);

$server->listen('0.0.0.0', 9501);

Pitfalls

WARNING

• Protocol flags go to the parent. createSubServer() writes the flags to the parent server's settings, not to the sub-server. If the parent also serves HTTP, check the combined flags before you start.

WARNING

• Calling listen() on a sub-server only registers it. The port opens when the parent calls listen(). Calling the sub-server's listen() after the parent has started does nothing.

• Tip: Bind errors appear at parent start. A port that is already in use fails during the parent's listen(), not when the sub-server is created.