How to handle message sent from server to client with RSocket? - spring-webflux

Question

I try to use RSocketRequester to send a message from the server to the specific client, but I don't know how to handle it on the frontend. The server is Spring Webflux with the controller like this:
data class Message(val message: String)
#Controller
class RSocketController {
private val log = LoggerFactory.getLogger(RSocketController::class.java)
#MessageMapping("say.hello")
fun sayHello(message: String): Flux<Message> {
log.info("say hello {}", message)
return Flux.just(Message("server says hello"))
}
#MessageMapping("say.hi")
fun sayHi(message: String, rSocketRequester: RSocketRequester): Flux<Message> {
log.info("say hi {}", message)
rSocketRequester
.route("say.hello")
.data(Message("server says hi hello ;)"))
.send()
.subscribe()
return Flux.just(Message("server says hi!!"))
}
}
On the frontend I use rsocket-js. The sayHello method works just fine (request-stream), but when I call the sayHi method I want to send two messages from the server. The first one to say.hello endpoint, and the second to say.hi endpoint. I've got rsocket-js implementation like this:
sayHello() {
console.log("say hello");
this.requestStream("say.hello");
},
sayHi() {
console.log("say hi");
this.requestStream("say.hi");
},
connect() {
const transport = new RSocketWebSocketClient({
url: "ws://localhost:8080/rsocket"
});
const client = new RSocketClient({
serializers: {
data: JsonSerializer,
metadata: IdentitySerializer
},
setup: {
keepAlive: 60000,
lifetime: 180000,
dataMimeType: "application/json",
metadataMimeType: "message/x.rsocket.routing.v0"
},
transport
});
client.connect().subscribe({
onComplete: socket => {
this.socket = socket;
console.log("complete connection");
},
onError: error => {
console.log("got connection error");
console.error(error);
},
onSubscribe: cancel => {
console.log("subscribe connection");
console.log(cancel);
}
});
},
requestStream(url) {
if (this.socket) {
this.socket
.requestStream({
data: url + " from client",
metadata: String.fromCharCode(url.length) + url
})
.subscribe({
onComplete: () => console.log("requestStream done"),
onError: error => {
console.log("got error with requestStream");
console.error(error);
},
onNext: value => {
// console.log("got next value in requestStream..");
console.log("got data from sever");
console.log(value.data);
},
// Nothing happens until `request(n)` is called
onSubscribe: sub => {
console.log("subscribe request Stream!");
sub.request(2147483647);
// sub.request(3);
}
});
} else {
console.log("not connected...");
}
}
I can see both messages in Google Chrome DevTools -> Network -> rsocket. So the client receives them but I can't catch in the code the one sent by RSocketRequester.
It seems that the server uses fireAndForget method. How to handle it on the client side?

Answer 1

As #VladMamaev said, we can provide a responder to the client like in this example https://github.com/rsocket/rsocket-js/blob/master/packages/rsocket-examples/src/LeaseClientExample.js#L104
For me, fireAndForget method is enough.
export class EchoResponder {
constructor(callback) {
this.callback = callback;
}
fireAndForget(payload) {
this.callback(payload);
}
}
import { EchoResponder } from "~/assets/EchoResponder";
...
const messageReceiver = payload => {
//do what you want to do with received message
console.log(payload)
};
const responder = new EchoResponder(messageReceiver);
connect() {
const transport = new RSocketWebSocketClient({
url: "ws://localhost:8080/rsocket"
});
const client = new RSocketClient({
serializers: {
data: JsonSerializer,
metadata: IdentitySerializer
},
setup: {
keepAlive: 60000,
lifetime: 180000,
dataMimeType: "application/json",
metadataMimeType: "message/x.rsocket.routing.v0"
},
responder: responder,
transport
});