How to receive streamed response from KSQL in Spring Kafka?

How to receive chunked response from kafka KSQL server in java spring boot app?

When I make a rest call to the /query endpoint I just get 1 row and the connection closes. How can I keep the connection open and receive multiple rows?

The doc says

The response is streamed back until the LIMIT specified in the
statement is reached, or the client closes the connection.

What's the way to achieve this in java? Even for KTable I get only 1 row in return.

https://docs.confluent.io/current/ksql/docs/developer-guide/api.html#run-a-query-and-stream-back-the-output

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

add a comment |

How to receive chunked response from kafka KSQL server in java spring boot app?

When I make a rest call to the /query endpoint I just get 1 row and the connection closes. How can I keep the connection open and receive multiple rows?

The doc says

The response is streamed back until the LIMIT specified in the
statement is reached, or the client closes the connection.

What's the way to achieve this in java? Even for KTable I get only 1 row in return.

https://docs.confluent.io/current/ksql/docs/developer-guide/api.html#run-a-query-and-stream-back-the-output

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

add a comment |

How to receive chunked response from kafka KSQL server in java spring boot app?

When I make a rest call to the /query endpoint I just get 1 row and the connection closes. How can I keep the connection open and receive multiple rows?

The doc says

The response is streamed back until the LIMIT specified in the
statement is reached, or the client closes the connection.

What's the way to achieve this in java? Even for KTable I get only 1 row in return.

https://docs.confluent.io/current/ksql/docs/developer-guide/api.html#run-a-query-and-stream-back-the-output

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

How to receive chunked response from kafka KSQL server in java spring boot app?

When I make a rest call to the /query endpoint I just get 1 row and the connection closes. How can I keep the connection open and receive multiple rows?

The doc says

The response is streamed back until the LIMIT specified in the
statement is reached, or the client closes the connection.

What's the way to achieve this in java? Even for KTable I get only 1 row in return.

https://docs.confluent.io/current/ksql/docs/developer-guide/api.html#run-a-query-and-stream-back-the-output

java apache-kafka ksql

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

edited Jan 20 at 0:20

cricket_007

81.3k1142111

edited Jan 20 at 0:20

cricket_007

81.3k1142111

edited Jan 20 at 0:20

cricket_007

81.3k1142111

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

asked Jan 19 at 13:51

Sergei Ledvanov

85331335

add a comment |

1 Answer
1

active

oldest

votes

The way I was able to work it around is the following:

get the response as a String

parse JSON objects line by line (KafkaQueryResponse is an object that represents 1 row)

    ResponseEntity<String> result = template.exchange("/query",

        HttpMethod.POST,

        new HttpEntity<>(params, headers),

        String.class);



    List<KafkaQueryResponse> array = new ArrayList<>();

    JsonFactory jsonFactory = new JsonFactory();

    try(BufferedReader br = new BufferedReader(new StringReader(result.getBody()))) {

        Iterator<KafkaQueryResponse> value = objectMapper.readValues(jsonFactory.createParser(br), KafkaQueryResponse.class);

        value.forEachRemaining(e -> {

            if (e.getRow() != null) {

                array.add(e);

            }

        });

    }

    array <----  this is the list of JSON objects

KafkaQueryResponse

    @Data

    @JsonIgnoreProperties(ignoreUnknown = true)

    public class KafkaQueryResponse {

        private KafkaQueryRow row;

        private String finalMessage;

        private String errorMessage;



        @Data

        @JsonIgnoreProperties(ignoreUnknown = true)

        public static class KafkaQueryRow {

            private List<Object> columns;

        }

    }

This solution does not allow reading the streamed response in chunks. It waits for the whole response to arrive to the client, then closes the connection and then parses all json objects.

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

The way I was able to work it around is the following:

get the response as a String

parse JSON objects line by line (KafkaQueryResponse is an object that represents 1 row)

    ResponseEntity<String> result = template.exchange("/query",

        HttpMethod.POST,

        new HttpEntity<>(params, headers),

        String.class);



    List<KafkaQueryResponse> array = new ArrayList<>();

    JsonFactory jsonFactory = new JsonFactory();

    try(BufferedReader br = new BufferedReader(new StringReader(result.getBody()))) {

        Iterator<KafkaQueryResponse> value = objectMapper.readValues(jsonFactory.createParser(br), KafkaQueryResponse.class);

        value.forEachRemaining(e -> {

            if (e.getRow() != null) {

                array.add(e);

            }

        });

    }

    array <----  this is the list of JSON objects

KafkaQueryResponse

    @Data

    @JsonIgnoreProperties(ignoreUnknown = true)

    public class KafkaQueryResponse {

        private KafkaQueryRow row;

        private String finalMessage;

        private String errorMessage;



        @Data

        @JsonIgnoreProperties(ignoreUnknown = true)

        public static class KafkaQueryRow {

            private List<Object> columns;

        }

    }

This solution does not allow reading the streamed response in chunks. It waits for the whole response to arrive to the client, then closes the connection and then parses all json objects.

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

add a comment |

The way I was able to work it around is the following:

get the response as a String

parse JSON objects line by line (KafkaQueryResponse is an object that represents 1 row)

    ResponseEntity<String> result = template.exchange("/query",

        HttpMethod.POST,

        new HttpEntity<>(params, headers),

        String.class);



    List<KafkaQueryResponse> array = new ArrayList<>();

    JsonFactory jsonFactory = new JsonFactory();

    try(BufferedReader br = new BufferedReader(new StringReader(result.getBody()))) {

        Iterator<KafkaQueryResponse> value = objectMapper.readValues(jsonFactory.createParser(br), KafkaQueryResponse.class);

        value.forEachRemaining(e -> {

            if (e.getRow() != null) {

                array.add(e);

            }

        });

    }

    array <----  this is the list of JSON objects

KafkaQueryResponse

    @Data

    @JsonIgnoreProperties(ignoreUnknown = true)

    public class KafkaQueryResponse {

        private KafkaQueryRow row;

        private String finalMessage;

        private String errorMessage;



        @Data

        @JsonIgnoreProperties(ignoreUnknown = true)

        public static class KafkaQueryRow {

            private List<Object> columns;

        }

    }

This solution does not allow reading the streamed response in chunks. It waits for the whole response to arrive to the client, then closes the connection and then parses all json objects.

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

add a comment |

The way I was able to work it around is the following:

get the response as a String

parse JSON objects line by line (KafkaQueryResponse is an object that represents 1 row)

    ResponseEntity<String> result = template.exchange("/query",

        HttpMethod.POST,

        new HttpEntity<>(params, headers),

        String.class);



    List<KafkaQueryResponse> array = new ArrayList<>();

    JsonFactory jsonFactory = new JsonFactory();

    try(BufferedReader br = new BufferedReader(new StringReader(result.getBody()))) {

        Iterator<KafkaQueryResponse> value = objectMapper.readValues(jsonFactory.createParser(br), KafkaQueryResponse.class);

        value.forEachRemaining(e -> {

            if (e.getRow() != null) {

                array.add(e);

            }

        });

    }

    array <----  this is the list of JSON objects

KafkaQueryResponse

    @Data

    @JsonIgnoreProperties(ignoreUnknown = true)

    public class KafkaQueryResponse {

        private KafkaQueryRow row;

        private String finalMessage;

        private String errorMessage;



        @Data

        @JsonIgnoreProperties(ignoreUnknown = true)

        public static class KafkaQueryRow {

            private List<Object> columns;

        }

    }

This solution does not allow reading the streamed response in chunks. It waits for the whole response to arrive to the client, then closes the connection and then parses all json objects.

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

The way I was able to work it around is the following:

get the response as a String

parse JSON objects line by line (KafkaQueryResponse is an object that represents 1 row)

    ResponseEntity<String> result = template.exchange("/query",

        HttpMethod.POST,

        new HttpEntity<>(params, headers),

        String.class);



    List<KafkaQueryResponse> array = new ArrayList<>();

    JsonFactory jsonFactory = new JsonFactory();

    try(BufferedReader br = new BufferedReader(new StringReader(result.getBody()))) {

        Iterator<KafkaQueryResponse> value = objectMapper.readValues(jsonFactory.createParser(br), KafkaQueryResponse.class);

        value.forEachRemaining(e -> {

            if (e.getRow() != null) {

                array.add(e);

            }

        });

    }

    array <----  this is the list of JSON objects

KafkaQueryResponse

    @Data

    @JsonIgnoreProperties(ignoreUnknown = true)

    public class KafkaQueryResponse {

        private KafkaQueryRow row;

        private String finalMessage;

        private String errorMessage;



        @Data

        @JsonIgnoreProperties(ignoreUnknown = true)

        public static class KafkaQueryRow {

            private List<Object> columns;

        }

    }

This solution does not allow reading the streamed response in chunks. It waits for the whole response to arrive to the client, then closes the connection and then parses all json objects.

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

answered Jan 20 at 12:22

Sergei Ledvanov

85331335

add a comment |

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