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"));
