Subscribe to Flux Websocket inbound connection with projectreactor blocking? - intellij-idea

Question

In the below code, IntelliJ warns the subscribe should not be called in a blocking scope. Unfortunately subscribe seems to be the most intuitive way of associating a consumer with the inbound message stream, is there a better way?
Code snippet in Kotlin, based on the example Java code in the projectreactor documentation.
I want to subscribe to the inbound messages with a consumer that is injected, or expose the inbound messages flux in a way that other consumers can access and subscribe to it and I don't want this to be blocking.
import io.netty.buffer.Unpooled
import io.netty.util.CharsetUtil
import reactor.core.publisher.Flux
import reactor.netty.http.client.HttpClient
fun main() {
HttpClient.create()
.websocket()
.uri("wss://echo.websocket.org")
.handle { inbound, outbound ->
inbound.receive()
.asString()
.take(1)
.subscribe(
{ println(it) },
{ println("error $it") },
{ println("completed") }
)
val msgBytes = "hello".toByteArray(CharsetUtil.ISO_8859_1)
outbound.send(Flux.just(Unpooled.wrappedBuffer(msgBytes))).neverComplete()
}
.blockLast()
}

Answer 1

We found an alternative to subscribe that was non-blocking. then and zip. Example in Kotlin.
import io.netty.buffer.Unpooled
import io.netty.util.CharsetUtil.UTF_8
import reactor.core.publisher.Flux
import reactor.netty.http.client.HttpClient
fun main() {
val outgoingMessagesFlux = Flux.just(Unpooled.wrappedBuffer("hello".toByteArray(UTF_8)))
HttpClient.create()
.websocket()
.uri("wss://echo.websocket.org")
.handle { inbound, outbound ->
val thenInbound = inbound.receive()
.asString()
.doOnNext { println(it) }
.then()
val thenOutbound = outbound.send(outgoingMessagesFlux).neverComplete()
Flux.zip(thenInbound, thenOutbound).then()
}.blockLast()
}
This was based on the Spring WebFlux Netty websocket client source code implementation and the current spring-framework documentation.