BodyCodec and pipe method forward status code - vert.x

Question

I would like to ask about error handling for streaming with body codec and pipe method.
I am having GateWay and Storage services communicating via HTTP.
A user can send GET request to GateWay which forwards the request to Storage service which responses with the required file.
The problem is when the file is not found. In this case, the user receives a response with status 200 and status message OK.
It seems that response with status 404 is never received by the GateWay Service (or at least not before the response is already sent) but the HttpServerRequest response is ended with status 200.
Is there any way that the GateWay service forwards the status code from the Storage service response to user ????
Thank you
GateWay Service:
httpClientRequest.as(BodyCodec.pipe(request.response().setChunked(true))).rxSend()
.subscribe(
response -> {
if (response.statusCode() != OK_STATUS) {
routingContext.response().setStatusCode(response.statusCode()).end();
}
},
error -> LOG.error("KO")
);
Storage Service:
var options = new OpenOptions().setRead(true).setCreate(false).setWrite(false);
request.pause();
fileSystem
.rxOpen("pathToFile", options)
.flatMapCompletable(asyncFile -> asyncFile.rxPipeTo(request.response()))
.subscribe(
() -> LOG.info("OK"),
error -> {
request.resume();
routingContext.response()
.setStatusCode(404)
.setStatusMessage("File not found")
.end();
}
);
Communication schema

Answer 1

The WebClient pushes response bytes to the body codec before the Single returned by rxSend completes. This is by design, as the WebClient only operates by buffering content before handing it over to the user.
For your use case, it would be better to work with the raw HttpClient.
request.response().setChunked(true);
HttpClientRequest httpClientRequest = httpClient.get(port, host, requestURI);
httpClientRequest
.handler(httpClientResponse -> {
if (httpClientResponse.statusCode() != OK_STATUS) {
routingContext.response().setStatusCode(httpClientResponse.statusCode()).end();
} else {
httpClientResponse.pipeTo(request.response(), ar -> {
if (ar.failed()) {
LOG.error("KO");
}
});
}
}).exceptionHandler(t -> handleConnectionFailure(t)).end();