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From Conrad Crampton <conrad.cramp...@gmail.com>
Subject ClassCastException in KStreams job for SessionWindow aggregation
Date Wed, 02 May 2018 15:12:09 GMT
I'm trying to window over http logs and create an HttpSession i.e. a list
of http requests (and some other properties). However when in my aggregate
Merger part (I think) I'm getting a classcastexception I think in when my
sessions are being merged and cannot for the life of me work out why.
The exception is at the bottom and I think the relevant code is here.
Can anyone give a suggestion as to why Http is trying to be cast to
HttpSession?
Thanks


final Serializer<Http> httpSerializer = new JsonPOJOSerializer<>();
        serdeProps.put("JsonPOJOClass", Http.class);
        httpSerializer.configure(serdeProps, false);

        final Deserializer<Http> httpDeserializer = new
JsonPOJODeserializer<>();
        serdeProps.put("JsonPOJOClass", Http.class);
        httpDeserializer.configure(serdeProps, false);

        final Serde<Http> httpSerde = Serdes.serdeFrom(httpSerializer,
httpDeserializer);

        final Serializer<HttpSession> httpSessionSerializer = new
JsonPOJOSerializer<>();
        serdeProps.put("JsonPOJOClass", Http.class);
        httpSessionSerializer.configure(serdeProps, false);

        final Deserializer<HttpSession> httpSessionDeserializer = new
JsonPOJODeserializer<>();
        serdeProps.put("JsonPOJOClass", Http.class);
        httpSessionDeserializer.configure(serdeProps, false);

        final Serde<HttpSession> httpSessionSerde =
Serdes.serdeFrom(httpSessionSerializer, httpSessionDeserializer);

        StreamsBuilder builder = new StreamsBuilder();

        KStream<String, HttpSession> httpStream = null;
        try {
            httpStream = builder.stream(
                    config.getString(ConfigConstants.HTTP_TOPIC_KEY),
                    Consumed.with(Serdes.String(), httpSerde))
                    .selectKey((s, http) -> http.getClient() +
http.getSourceIp() + http.getUseragent())
                    .groupByKey(Serialized.with(Serdes.String(), httpSerde))
                    // window by session

.windowedBy(SessionWindows.with(TimeUnit.MINUTES.toMillis(10)))
                    .aggregate(
                            new Initializer<HttpSession>() {
                                @Override
                                public HttpSession apply() {
                                    return new HttpSession();
                                }
                            },
                            new Aggregator<String, Http, HttpSession>() {
                                @Override
                                public HttpSession apply(String s, Http
http, HttpSession session) {
                                    return session.addRequest(http);
                                }
                            },
                            new Merger<String, HttpSession>() {
                                 @Override
                                 public HttpSession apply(String s,
HttpSession session, HttpSession v1)
                                     log.debug("merging key {}, session {}
with other {}", s, session, v1);
                                     return session.merge(v1);}
},
                            Materialized.<String, HttpSession,
SessionStore<Bytes,
byte[]>>as(config.getString(StreamsConfig.APPLICATION_ID_CONFIG) +
"-session-store").withKeySerde(Serdes.String()).withValueSerde(httpSessionSerde)
                    ).toStream((stringWindowed, session) ->
(stringWindowed.key()));
        } catch (Exception e) {
            e.printStackTrace();
        }

        httpStream
                .filter((key, message) -> message != null)
                .filter((key, message) -> message.getClient() != null)
                .filter((key, message) ->
httpClients.stream().anyMatch(message.getClient()::equals))
                .foreach((key, message) -> {
                    log.info("message {}", message);
                });

        final KafkaStreams streams = new KafkaStreams(builder.build(),
props);
        streams.start();

java.lang.ClassCastException: com.secdata.gi.graph.model.Http cannot be
cast to com.secdata.gi.graph.model.HttpSession
at com.secdata.gi.graph.Process$$Lambda$45/1474607212.apply(Unknown Source)
at
org.apache.kafka.streams.kstream.internals.KStreamImpl$2.apply(KStreamImpl.java:157)
at
org.apache.kafka.streams.kstream.internals.KStreamImpl$2.apply(KStreamImpl.java:154)
at
org.apache.kafka.streams.kstream.internals.KStreamMap$KStreamMapProcessor.process(KStreamMap.java:41)
at
org.apache.kafka.streams.processor.internals.ProcessorNode$1.run(ProcessorNode.java:46)
at
org.apache.kafka.streams.processor.internals.StreamsMetricsImpl.measureLatencyNs(StreamsMetricsImpl.java:208)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:124)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:85)
at
org.apache.kafka.streams.kstream.internals.KStreamMapValues$KStreamMapProcessor.process(KStreamMapValues.java:41)
at
org.apache.kafka.streams.processor.internals.ProcessorNode$1.run(ProcessorNode.java:46)
at
org.apache.kafka.streams.processor.internals.StreamsMetricsImpl.measureLatencyNs(StreamsMetricsImpl.java:208)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:124)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:85)
at
org.apache.kafka.streams.kstream.internals.ForwardingCacheFlushListener.apply(ForwardingCacheFlushListener.java:42)
at
org.apache.kafka.streams.state.internals.CachingSessionStore.putAndMaybeForward(CachingSessionStore.java:176)
at
org.apache.kafka.streams.state.internals.CachingSessionStore.access$000(CachingSessionStore.java:38)
at
org.apache.kafka.streams.state.internals.CachingSessionStore$1.apply(CachingSessionStore.java:88)
at
org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:141)
at
org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:99)
at
org.apache.kafka.streams.state.internals.ThreadCache.flush(ThreadCache.java:127)
at
org.apache.kafka.streams.state.internals.CachingSessionStore.flush(CachingSessionStore.java:196)
at
org.apache.kafka.streams.state.internals.CachingSessionStore.close(CachingSessionStore.java:201)
at
org.apache.kafka.streams.state.internals.WrappedStateStore$AbstractStateStore.close(WrappedStateStore.java:89)
at
org.apache.kafka.streams.processor.internals.ProcessorStateManager.close(ProcessorStateManager.java:275)
at
org.apache.kafka.streams.processor.internals.AbstractTask.closeStateManager(AbstractTask.java:238)
at
org.apache.kafka.streams.processor.internals.StreamTask.closeSuspended(StreamTask.java:450)
at
org.apache.kafka.streams.processor.internals.StreamTask.close(StreamTask.java:532)
at
org.apache.kafka.streams.processor.internals.AssignedTasks.close(AssignedTasks.java:500)
at
org.apache.kafka.streams.processor.internals.AssignedTasks.close(AssignedTasks.java:493)
at
org.apache.kafka.streams.processor.internals.TaskManager.shutdown(TaskManager.java:212)
at
org.apache.kafka.streams.processor.internals.StreamThread.completeShutdown(StreamThread.java:1213)
at
org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:755)

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