Storm Cassandra 集成

Apache Cassandra 的 Bolt API 实现

这个库提供了 Apache Cassandra 之上的核心 storm bolt . 提供简单的 DSL 来 map storm Tuple 到 Cassandra Query Language Statement (Cassandra 查询语言 Statement).

Configuration (配置)

以下属性可能会传递给 storm 配置.

Property name(属性名称) Description(描述) Default(默认)
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)

CassandraWriterBolt

Static import


import static org.apache.storm.cassandra.DynamicStatementBuilder.*

Insert Query Builder (插入查询生成器)

Insert query including only the specified tuple fields (插入仅包含指定 tuple 字段的查询).

    new CassandraWriterBolt(
        async(
            simpleQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);")
                .with(
                    fields("title", "year", "performer", "genre", "tracks")
                 )
            )
    );
Insert query including all tuple fields(插入包含所有 tuple 字段的查询).

    new CassandraWriterBolt(
        async(
            simpleQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);")
                .with( all() )
            )
    );
Insert multiple queries from one input tuple (从一个 input tuple 插入多个查询).

    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()))
        )
    );
Insert query using QueryBuilder(使用 QueryBuilder 插入查询)

    new CassandraWriterBolt(
        async(
            simpleQuery("INSERT INTO album (title,year,perfomer,genre,tracks) VALUES (?, ?, ?, ?, ?);")
                .with(all()))
            )
    )
Insert query with static bound query (使用 static bound query 插入 查询)

    new CassandraWriterBolt(
         async(
            boundQuery("INSERT INTO album (title,year,performer,genre,tracks) VALUES (?, ?, ?, ?, ?);")
                .bind(all());
         )
    );
Insert query with static bound query using named setters and aliases (使用 named setters 和 aliases 插入带有 static bound query 的查询)

    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()
         )
    );
Insert query with bound statement load from storm configuration (从 storm 配置插入 bound statement load 的查询)

    new CassandraWriterBolt(
         boundQuery(named("insertIntoAlbum"))
            .bind(all());
Insert query with bound statement load from tuple field (从 tuple 字段插入 bound statement load 的查询)

    new CassandraWriterBolt(
         boundQuery(namedByField("cql"))
            .bind(all());
Insert query with batch statement (使用 batch 语句插入查询)

    // 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()))
        )
    );

如何处理 query execution results (查询执行结果)

ExecutionResultHandler 接口可用于自定义 execution result (执行结果)应如何处理.

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);
}

默认情况下, CassandraBolt 将在所有的 Cassandra Exception 中 fails(失败)一个 tuple (请参阅 BaseExecutionResultHandler).

    new CassandraWriterBolt(insertInto("album").values(with(all()).build())
            .withResultHandler(new MyCustomResultHandler());

Declare Output fields (声明输出字段)

CassandraBolt 可以声明 declare output fields / stream output fields(输出字段/流输出字段). 例如, 这可以用于在 error (错误)或者 chain queries (链式查询)上 remit (传递)一个 new tuple (新的元组).

    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);
        }
    }

Murmur3FieldGrouping

Murmur3StreamGrouping 可以用来优化 cassandra writes (cassandra 的写入). 根据 specified row partition keys (指定的行分区键), 该 stream 在 bolt 的 task 之间进行 partitioned (分区).

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"))

Trident API 支持

storm-cassandra 支持 用于将 data inserting(插入) Cassandra 的 Trident state API . java 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());

以下 state API 用于从 Cassandra querying(查询) 数据. java 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"));


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