public static StormTopology buildTopology() {
TridentTopology topology = new TridentTopology();
DiagnosisEventSpout spout = new DiagnosisEventSpout();
Stream inputStream = topology.newStream("event", spout);
inputStream
// Filter for critical events.
.each(new Fields("event"), new DiseaseFilter())
// Locate the closest city
.each(new Fields("event"), new CityAssignment(), new Fields("city"))
// Derive the hour segment
.each(
new Fields("event", "city"),
new HourAssignment(),
new Fields("hour", "cityDiseaseHour"))
// Group occurrences in same city and hour
.groupBy(new Fields("cityDiseaseHour"))
// Count occurrences and persist the results.
.persistentAggregate(new OutbreakTrendFactory(), new Count(), new Fields("count"))
.newValuesStream()
// Detect an outbreak
.each(
new Fields("cityDiseaseHour", "count"),
new OutbreakDetector(),
new Fields("alert")) // Dispatch the alert
.each(new Fields("alert"), new DispatchAlert(), new Fields());
return topology.build();
}
@Test
public void testTridentTopology() throws Exception {
Session session = cassandraCQLUnit.session;
String[] stationIds = {"station-1", "station-2", "station-3"};
for (int i = 1; i < 4; i++) {
ResultSet resultSet =
session.execute(
"INSERT INTO weather.station(id, name) VALUES(?, ?)",
stationIds[i - 1],
"Foo-Station-" + new Random().nextInt());
}
ResultSet rows = cassandraCQLUnit.session.execute("SELECT * FROM weather.station");
for (Row row : rows) {
System.out.println("####### row = " + row);
}
WeatherBatchSpout weatherBatchSpout =
new WeatherBatchSpout(
new Fields("weather_station_id", "temperature", "event_time"), 3, stationIds);
TridentTopology topology = new TridentTopology();
Stream stream = topology.newStream("cassandra-trident-stream", weatherBatchSpout);
CassandraStateFactory insertValuesStateFactory = getInsertTemperatureStateFactory();
CassandraStateFactory selectWeatherStationStateFactory = getSelectWeatherStationStateFactory();
TridentState selectState = topology.newStaticState(selectWeatherStationStateFactory);
stream =
stream.stateQuery(
selectState,
new Fields("weather_station_id"),
new CassandraQuery(),
new Fields("name"));
stream = stream.each(new Fields("name"), new PrintFunction(), new Fields("name_x"));
stream.partitionPersist(
insertValuesStateFactory,
new Fields("weather_station_id", "name", "event_time", "temperature"),
new CassandraStateUpdater(),
new Fields());
StormTopology stormTopology = topology.build();
LocalCluster cluster = new LocalCluster();
cluster.submitTopology("wordCounter", getConfig(), stormTopology);
Thread.sleep(30 * 1000);
rows = cassandraCQLUnit.session.execute("SELECT * FROM weather.temperature");
Assert.assertTrue(rows.iterator().hasNext()); // basic sanity check
cluster.killTopology("wordCounter");
cluster.shutdown();
}
@Override
protected Stream createTracesStream(Stream stream) {
return stream.each(
new Fields("str"), new JsonToTrace(sessionId), new Fields("versionId", "trace"));
}