rxHCResponse.asObservable() would't call onNext when work with Vertx.timer

[zhangpp520]

First I defined a Observable

Observable participants(){
return new RxHttpClient(..).request("GET",path,requestBuilder-> {
requestBuilder.end();
}).flatMap(rxHCResponse -> {
return rxHCResponse.asObservable().reduce(new Buffer(), RxSupport.mergeBuffers).map(buffer-> {
//never called !!!!
return new JsonObject(buffer.toString());
});
});
}

then

vertx.setTimer(1000, timerId -> {
participants().subscribe(result-> {
System.out.println(result);
})
});

I found I can't get anything from the Observable.

[petermd]

Hi,

is the problem specific to calling subscribe() from a timer?

it would be really helpful if you had a minimal test that reproduced the issue?

Thanks,
Peter

[zhangpp520]

import io.vertx.rxcore.RxSupport;
import io.vertx.rxcore.java.http.RxHttpClient;
import org.vertx.java.core.buffer.Buffer;
import org.vertx.java.platform.Verticle;
import rx.Observable;

public class Test extends Verticle {
    public void start() {
        RxHttpClient httpClient = new RxHttpClient(vertx.createHttpClient().setHost("www.baidu.com"));
        Observable<String> ob= httpClient.request("GET", "/", requestBuilder -> {
            requestBuilder.end();
        }).flatMap(rxHCResponse -> {
            return rxHCResponse.asObservable().reduce(new Buffer(), RxSupport.mergeBuffers).map(buffer -> {
                return buffer.toString();
            });
        });

        ob.subscribe(c -> {
            //this can print
            System.out.println(c);
        });

        vertx.setTimer(1000, timerId -> {
            ob.subscribe(c -> {
                //this can't print
                System.out.println(c);
            });
        });
    }
}

The command is 'vertx run Test.java -includes io.vertxmod-rxvertx1.0.0-beta4'。
If I subscribe the ob inside the timer,I can't get anything.

[zhangpp520]

And I find when I post data,there is a strange program.
If I use the format requestBuilder.end(data),it's Ok.
But when I use the format requestBuilder.write(data).end(),the server can't get the data occasionally.

[zhangpp520]

I think it's same as the #5。If I wrap the Observable into Func,it works well.
So how can I make rxHttpClient lazily executed?

[petermd]

Hi @zhangpp520,

right - it is the same issue as #5, so there are two options

1. add cache() immediately to the generated Observable so the request results are stored and replayed to all subscribers
2. we change the behaviour to execute-on-subscribe
   1. by modifying the existing methods
   2. by adding a new set of observeMETHOD requests

Since it's a legacy library I'd suggest that 2(ii) is safer and hopefully the correct semantics can be implemented from the start in Vert.x 3

-Peter

[zhangpp520]

Thank you so much,Peter!
You gave me great help when I was learning RxJava and rxvertx.
I find another problem due to the wrong semantics.

       rxHttpClient.request("GET",path,requestBuilder-> {
            requestBuilder.setTimeout(1000).end();
        }).flatMap(rxHCResponse -> {
            return rxHCResponse.asObservable().reduce(new Buffer(),       RxSupport.mergeBuffers).map(buffer -> {
                return new JsonObject(buffer.toString());
            });
        }).onErrorResumeNext(throwable -> {
            return Observable.just(new JsonObject());
        }).flatMap(rs-> {
              return Observable.just("never return").map(s-> {
                   return s;
              );
        }).subscribe(r-> {
              //never call
        });

If a latMap is subsequent to an http Observable,when there is an error occur and the stream resume by the onErrorResumeNext method,the subscribe method never call.I can use cache() to workround that.

Maybe I can add an observerequest method and pull a request,I will try that.

Thank you!