This library provides core storm bolt on top of Apache Cassandra. Provides simple DSL to map storm Tuple to Cassandra Query Language Statement.
The following properties may be passed to storm configuration.
Property name | Description | Default |
---|---|---|
cassandra.keyspace | - | |
cassandra.nodes | - | {“localhost”} |
cassandra.username | - | - |
cassandra.password | - | - |
cassandra.port | - | 9092 |
cassandra.output.consistencyLevel | - | ONE |
cassandra.batch.size.rows | - | 100 |
cassandra.retryPolicy | - | DefaultRetryPolicy |
cassandra.reconnectionPolicy.baseDelayMs | - | 100 (ms) |
cassandra.reconnectionPolicy.maxDelayMs | - | 60000 (ms) |
####Static import
import static org.apache.storm.cassandra.DynamicStatementBuilder.*
new CassandraWriterBolt( async( simpleQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);") .with( fields("title", "year", "performer", "genre", "tracks") ) ) );
new CassandraWriterBolt( async( simpleQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);") .with( all() ) ) );
new CassandraWriterBolt( async( simpleQuery("INSERT INTO titles_per_album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())), simpleQuery("INSERT INTO titles_per_performer (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())) ) );
new CassandraWriterBolt( async( simpleQuery("INSERT INTO album (title,year,perfomer,genre,tracks) VALUES (?, ?, ?, ?, ?);") .with(all())) ) )
new CassandraWriterBolt( async( boundQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);") .bind(all()); ) );
new CassandraWriterBolt( async( boundQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (:ti, :ye, :pe, :ge, :tr);") .bind( field("ti"),as("title"), field("ye").as("year")), field("pe").as("performer")), field("ge").as("genre")), field("tr").as("tracks")) ).byNamedSetters() ) );
new CassandraWriterBolt( boundQuery(named("insertIntoAlbum")) .bind(all());
new CassandraWriterBolt( boundQuery(namedByField("cql")) .bind(all());
// Logged new CassandraWriterBolt(loggedBatch( simpleQuery("INSERT INTO titles_per_album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())), simpleQuery("INSERT INTO titles_per_performer (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())) ) ); // UnLogged new CassandraWriterBolt(unLoggedBatch( simpleQuery("INSERT INTO titles_per_album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())), simpleQuery("INSERT INTO titles_per_performer (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);").with(all())) ) );
The interface ExecutionResultHandler can be used to custom how an execution result should be handle.
public interface ExecutionResultHandler extends Serializable { void onQueryValidationException(QueryValidationException e, OutputCollector collector, Tuple tuple); void onReadTimeoutException(ReadTimeoutException e, OutputCollector collector, Tuple tuple); void onWriteTimeoutException(WriteTimeoutException e, OutputCollector collector, Tuple tuple); void onUnavailableException(UnavailableException e, OutputCollector collector, Tuple tuple); void onQuerySuccess(OutputCollector collector, Tuple tuple); }
By default, the CassandraBolt fails a tuple on all Cassandra Exception (see BaseExecutionResultHandler) .
new CassandraWriterBolt(insertInto("album").values(with(all()).build()) .withResultHandler(new MyCustomResultHandler());
A CassandraBolt can declare output fields / stream output fields. For instance, this may be used to remit a new tuple on error, or to chain queries.
new CassandraWriterBolt(insertInto("album").values(withFields(all()).build()) .withResultHandler(new EmitOnDriverExceptionResultHandler()); .withStreamOutputFields("stream_error", new Fields("message"); public static class EmitOnDriverExceptionResultHandler extends BaseExecutionResultHandler { @Override protected void onDriverException(DriverException e, OutputCollector collector, Tuple tuple) { LOG.error("An error occurred while executing cassandra statement", e); collector.emit("stream_error", new Values(e.getMessage())); collector.ack(tuple); } }
Murmur3StreamGrouping can be used to optimise cassandra writes. The stream is partitioned among the bolt's tasks based on the specified row partition keys.
CassandraWriterBolt bolt = new CassandraWriterBolt( insertInto("album") .values( with(fields("title", "year", "performer", "genre", "tracks") ).build()); builder.setBolt("BOLT_WRITER", bolt, 4) .customGrouping("spout", new Murmur3StreamGrouping("title"))
storm-cassandra support Trident state
API for inserting
data into Cassandra.
CassandraState.Options options = new CassandraState.Options(new CassandraContext()); CQLStatementTupleMapper insertTemperatureValues = boundQuery( "INSERT INTO weather.temperature(weather_station_id, weather_station_name, event_time, temperature) VALUES(?, ?, ?, ?)") .bind(with(field("weather_station_id"), field("name").as("weather_station_name"), field("event_time").now(), field("temperature"))); options.withCQLStatementTupleMapper(insertTemperatureValues); CassandraStateFactory insertValuesStateFactory = new CassandraStateFactory(options); 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());
Below state
API for querying
data from Cassandra.
CassandraState.Options options = new CassandraState.Options(new CassandraContext()); CQLStatementTupleMapper insertTemperatureValues = boundQuery("SELECT name FROM weather.station WHERE id = ?") .bind(with(field("weather_station_id").as("id"))); options.withCQLStatementTupleMapper(insertTemperatureValues); options.withCQLResultSetValuesMapper(new TridentResultSetValuesMapper(new Fields("name"))); CassandraStateFactory selectWeatherStationStateFactory = new CassandraStateFactory(options); CassandraStateFactory selectWeatherStationStateFactory = getSelectWeatherStationStateFactory(); TridentState selectState = topology.newStaticState(selectWeatherStationStateFactory); stream = stream.stateQuery(selectState, new Fields("weather_station_id"), new CassandraQuery(), new Fields("name"));