Unlike the WebSocket module (which is based on WebMVC), WebFlux provides us with client-side support too. In order to send a WebSocket connection request, we have the WebSocketClient class. WebSocketClient has two central methods to execute WebSocket connections, as shown in the following code sample:

public interface WebSocketClient {
   Mono<Void> execute(
      URI url,
      WebSocketHandler handler
   );
   Mono<Void> execute(
      URI url,
      HttpHeaders headers, 
      WebSocketHandler handler
   );
}

As we can see, WebSocketClient uses the same WebSockeHandler interface in order to process messages from the server and send messages back. There are a few WebSocketClient implementations that are related to the server engine, such as the TomcatWebSocketClient implementation or the JettyWebSocketClient implementation. In the following example, we will look at ReactorNettyWebSocketClient:

WebSocketClient client = new ReactorNettyWebSocketClient();

client.execute(
   URI.create("http://localhost:8080/ws/echo"),
   session -> Flux
      .interval(Duration.ofMillis(100))
      .map(String::valueOf)
      .map(session::textMessage)
      .as(session::send)
);

The preceding example shows how we can use ReactorNettyWebSocketClient to wire a WebSocket connection and start sending periodic messages to the server.