Creating Text Stream Using Spring WebFlux

up vote
0
down vote

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I've been using Spring WebFlux to create a text stream, here is the code.

@SpringBootApplication

@RestController

public class ReactiveServer {



    private static final String FILE_PATH = "c:/test/";





    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, value = "/events")

    Flux<String> events() {



        Flux<String> eventFlux = Flux.fromStream(Stream.generate(() -> FileReader.readFile()));



        Flux<Long> durationFlux = Flux.interval(Duration.ofMillis(500));



        return Flux.zip(eventFlux, durationFlux).map(Tuple2::getT1);



    }



    public static void main(String args) {



        SpringApplication.run(ReactiveServer.class, args);



    }



}

When I access the /events url on the browser I get this, that's almost what I want to get:

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542379993662,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":0,"rollingCountBadRequests":0}

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542379994203,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":2,"rollingCountBadRequests":0}

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542379994706,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":2,"rollingCountBadRequests":0}

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542379995213,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":3,"rollingCountBadRequests":0}

What I need to do is to insert a "ping:" in between iterations to get:

ping:

But, the best I could get was:

data: ping:

Does anyone know of a way to what I need?

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

add a comment |

up vote
0
down vote

favorite

I've been using Spring WebFlux to create a text stream, here is the code.

@SpringBootApplication

@RestController

public class ReactiveServer {



    private static final String FILE_PATH = "c:/test/";





    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, value = "/events")

    Flux<String> events() {



        Flux<String> eventFlux = Flux.fromStream(Stream.generate(() -> FileReader.readFile()));



        Flux<Long> durationFlux = Flux.interval(Duration.ofMillis(500));



        return Flux.zip(eventFlux, durationFlux).map(Tuple2::getT1);



    }



    public static void main(String args) {



        SpringApplication.run(ReactiveServer.class, args);



    }



}

When I access the /events url on the browser I get this, that's almost what I want to get:

What I need to do is to insert a "ping:" in between iterations to get:

ping:

But, the best I could get was:

data: ping:

Does anyone know of a way to what I need?

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

add a comment |

up vote
0
down vote

favorite

I've been using Spring WebFlux to create a text stream, here is the code.

@SpringBootApplication

@RestController

public class ReactiveServer {



    private static final String FILE_PATH = "c:/test/";





    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, value = "/events")

    Flux<String> events() {



        Flux<String> eventFlux = Flux.fromStream(Stream.generate(() -> FileReader.readFile()));



        Flux<Long> durationFlux = Flux.interval(Duration.ofMillis(500));



        return Flux.zip(eventFlux, durationFlux).map(Tuple2::getT1);



    }



    public static void main(String args) {



        SpringApplication.run(ReactiveServer.class, args);



    }



}

When I access the /events url on the browser I get this, that's almost what I want to get:

What I need to do is to insert a "ping:" in between iterations to get:

ping:

But, the best I could get was:

data: ping:

Does anyone know of a way to what I need?

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

I've been using Spring WebFlux to create a text stream, here is the code.

@SpringBootApplication

@RestController

public class ReactiveServer {



    private static final String FILE_PATH = "c:/test/";





    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, value = "/events")

    Flux<String> events() {



        Flux<String> eventFlux = Flux.fromStream(Stream.generate(() -> FileReader.readFile()));



        Flux<Long> durationFlux = Flux.interval(Duration.ofMillis(500));



        return Flux.zip(eventFlux, durationFlux).map(Tuple2::getT1);



    }



    public static void main(String args) {



        SpringApplication.run(ReactiveServer.class, args);



    }



}

When I access the /events url on the browser I get this, that's almost what I want to get:

What I need to do is to insert a "ping:" in between iterations to get:

ping:

But, the best I could get was:

data: ping:

Does anyone know of a way to what I need?

java spring-boot spring-webflux

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

edited yesterday

asked Nov 16 at 15:29

Nelson Larios

286

asked Nov 16 at 15:29

Nelson Larios

286

asked Nov 16 at 15:29

Nelson Larios

286

add a comment |

1 Answer
1

active

oldest

votes

up vote
0
down vote

You could try returning a Flux<ServerSentEvent> and specify the type of event you're trying to send. Like this:

@RestController

public class TestController {



    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, path = "/events")

    Flux<ServerSentEvent> events() {

        Flux<String> events = Flux.interval(Duration.ofMillis(200)).map(String::valueOf);

        Flux<ServerSentEvent<String>> sseData = events.map(event -> ServerSentEvent.builder(event).build());

        Flux<ServerSentEvent<String>> ping = Flux.interval(Duration.ofMillis(500))

                .map(l -> ServerSentEvent.builder("").event("ping").build());

        return Flux.merge(sseData, ping);

    }

}

With that code snippet, I'm getting the following output:

$ http --stream :8080/events

HTTP/1.1 200 OK

Content-Type: text/event-stream;charset=UTF-8

transfer-encoding: chunked



data:0



data:1



event:ping

data:



data:2



data:3



data:4



event:ping

data:

Which is consistent with Server Sent Events. Is the ping: prefix something specific to Hystrix? If it is, I don't think this is consistent with the SSE spec and that it's something supported in Spring Framework.

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this: data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}
– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

add a comment |

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1 Answer
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1 Answer
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active

oldest

votes

up vote
0
down vote

You could try returning a Flux<ServerSentEvent> and specify the type of event you're trying to send. Like this:

@RestController

public class TestController {



    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, path = "/events")

    Flux<ServerSentEvent> events() {

        Flux<String> events = Flux.interval(Duration.ofMillis(200)).map(String::valueOf);

        Flux<ServerSentEvent<String>> sseData = events.map(event -> ServerSentEvent.builder(event).build());

        Flux<ServerSentEvent<String>> ping = Flux.interval(Duration.ofMillis(500))

                .map(l -> ServerSentEvent.builder("").event("ping").build());

        return Flux.merge(sseData, ping);

    }

}

With that code snippet, I'm getting the following output:

$ http --stream :8080/events

HTTP/1.1 200 OK

Content-Type: text/event-stream;charset=UTF-8

transfer-encoding: chunked



data:0



data:1



event:ping

data:



data:2



data:3



data:4



event:ping

data:

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this: data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}
– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

add a comment |

up vote
0
down vote

You could try returning a Flux<ServerSentEvent> and specify the type of event you're trying to send. Like this:

@RestController

public class TestController {



    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, path = "/events")

    Flux<ServerSentEvent> events() {

        Flux<String> events = Flux.interval(Duration.ofMillis(200)).map(String::valueOf);

        Flux<ServerSentEvent<String>> sseData = events.map(event -> ServerSentEvent.builder(event).build());

        Flux<ServerSentEvent<String>> ping = Flux.interval(Duration.ofMillis(500))

                .map(l -> ServerSentEvent.builder("").event("ping").build());

        return Flux.merge(sseData, ping);

    }

}

With that code snippet, I'm getting the following output:

$ http --stream :8080/events

HTTP/1.1 200 OK

Content-Type: text/event-stream;charset=UTF-8

transfer-encoding: chunked



data:0



data:1



event:ping

data:



data:2



data:3



data:4



event:ping

data:

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this: data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}
– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

add a comment |

up vote
0
down vote

You could try returning a Flux<ServerSentEvent> and specify the type of event you're trying to send. Like this:

@RestController

public class TestController {



    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, path = "/events")

    Flux<ServerSentEvent> events() {

        Flux<String> events = Flux.interval(Duration.ofMillis(200)).map(String::valueOf);

        Flux<ServerSentEvent<String>> sseData = events.map(event -> ServerSentEvent.builder(event).build());

        Flux<ServerSentEvent<String>> ping = Flux.interval(Duration.ofMillis(500))

                .map(l -> ServerSentEvent.builder("").event("ping").build());

        return Flux.merge(sseData, ping);

    }

}

With that code snippet, I'm getting the following output:

$ http --stream :8080/events

HTTP/1.1 200 OK

Content-Type: text/event-stream;charset=UTF-8

transfer-encoding: chunked



data:0



data:1



event:ping

data:



data:2



data:3



data:4



event:ping

data:

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

You could try returning a Flux<ServerSentEvent> and specify the type of event you're trying to send. Like this:

@RestController

public class TestController {



    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE, path = "/events")

    Flux<ServerSentEvent> events() {

        Flux<String> events = Flux.interval(Duration.ofMillis(200)).map(String::valueOf);

        Flux<ServerSentEvent<String>> sseData = events.map(event -> ServerSentEvent.builder(event).build());

        Flux<ServerSentEvent<String>> ping = Flux.interval(Duration.ofMillis(500))

                .map(l -> ServerSentEvent.builder("").event("ping").build());

        return Flux.merge(sseData, ping);

    }

}

With that code snippet, I'm getting the following output:

$ http --stream :8080/events

HTTP/1.1 200 OK

Content-Type: text/event-stream;charset=UTF-8

transfer-encoding: chunked



data:0



data:1



event:ping

data:



data:2



data:3



data:4



event:ping

data:

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

edited yesterday

answered 2 days ago

Brian Clozel

28.9k67097

answered 2 days ago

Brian Clozel

28.9k67097

answered 2 days ago

Brian Clozel

28.9k67097

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this: data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}
– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

add a comment |

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this: data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547} data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}
– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

HI, Brian, thanks for you answer. What I'm trying to do is to create a data stream in exactly the way the Hystrix Dashboard expects it to be. I think it uses the "ping:" String between events as a kind of separation. So your answer gives me something like: So what I really need is just to print that "ping:" at the beginning of an event. But without the "data:". Like this: ping: Not like this: data:ping:
– Nelson Larios
yesterday

that's what my sample is doing: sending SSE events of type data (the default) and ping. They're currently just interleaved and the ping events are scheduled with a specific duration between them.
– Brian Clozel
yesterday

When I run your code "ping:" doesn't print. I get this:

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}

– Nelson Larios
yesterday

When I run your code "ping:" doesn't print. I get this:

data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382826545}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827046}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382827547}  data:{"type":"HystrixCommand","name":"GetConsumerCommand","group":"ConsumerRemoteGroup","currentTime":1542382828049}

– Nelson Larios
yesterday

I've edited my answer
– Brian Clozel
yesterday

Hi Brian, it's specific to Hystrix. It's a shame I can't do it with WebFlux. I close to a solution using reactivex. Thank you very much for you efforts.
– Nelson Larios
19 hours ago

add a comment |

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