RocketMQ integration for Apache Flink. This module includes the RocketMQ source and sink that allows a flink job to either write messages into a topic or read from topics in a flink job.
To use the RocketMQSource, you construct an instance of it by specifying a KeyValueDeserializationSchema instance and a Properties instance which including rocketmq configs.
RocketMQSource(KeyValueDeserializationSchema<OUT> schema, Properties props)
The RocketMQSource is based on RocketMQ pull consumer mode, and provides exactly once reliability guarantees when checkpoints are enabled.
Otherwise, the source doesn't provide any reliability guarantees.
The main API for deserializing topic and tags is the org.apache.rocketmq.flink.common.serialization.KeyValueDeserializationSchema interface.
rocketmq-flink includes general purpose KeyValueDeserializationSchema implementations called SimpleKeyValueDeserializationSchema.
public interface KeyValueDeserializationSchema<T> extends ResultTypeQueryable<T>, Serializable {
T deserializeKeyAndValue(byte[] key, byte[] value);
}To use the RocketMQSink, you construct an instance of it by specifying KeyValueSerializationSchema & TopicSelector instances and a Properties instance which including rocketmq configs.
RocketMQSink(KeyValueSerializationSchema<IN> schema, TopicSelector<IN> topicSelector, Properties props)
The RocketMQSink provides at-least-once reliability guarantees when checkpoints are enabled and withBatchFlushOnCheckpoint(true) is set.
Otherwise, the sink reliability guarantees depends on rocketmq producer's retry policy, for this case, the messages sending way is sync by default,
but you can change it by invoking withAsync(true).
The main API for serializing topic and tags is the org.apache.rocketmq.flink.common.serialization.KeyValueSerializationSchema interface.
rocketmq-flink includes general purpose KeyValueSerializationSchema implementations called SimpleKeyValueSerializationSchema.
public interface KeyValueSerializationSchema<T> extends Serializable {
byte[] serializeKey(T tuple);
byte[] serializeValue(T tuple);
}The main API for selecting topic and tags is the org.apache.rocketmq.flink.common.selector.TopicSelector interface.
rocketmq-flink includes general purpose TopicSelector implementations called DefaultTopicSelector and SimpleTopicSelector.
public interface TopicSelector<T> extends Serializable {
String getTopic(T tuple);
String getTag(T tuple);
}The following is an example which receive messages from RocketMQ brokers and send messages to broker after processing.
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
// enable checkpoint
env.enableCheckpointing(3000);
Properties consumerProps = new Properties();
consumerProps.setProperty(RocketMqConfig.NAME_SERVER_ADDR, "localhost:9876");
consumerProps.setProperty(RocketMqConfig.CONSUMER_GROUP, "c002");
consumerProps.setProperty(RocketMqConfig.CONSUMER_TOPIC, "flink-source2");
Properties producerProps = new Properties();
producerProps.setProperty(RocketMqConfig.NAME_SERVER_ADDR, "localhost:9876");
env.addSource(new RocketMQSource(new SimpleKeyValueDeserializationSchema("id", "address"), consumerProps))
.name("rocketmq-source")
.setParallelism(2)
.process(new ProcessFunction<Map, Map>() {
@Override
public void processElement(Map in, Context ctx, Collector<Map> out) throws Exception {
HashMap result = new HashMap();
result.put("id", in.get("id"));
String[] arr = in.get("address").toString().split("\\s+");
result.put("province", arr[arr.length-1]);
out.collect(result);
}
})
.name("upper-processor")
.setParallelism(2)
.addSink(new RocketMQSink(new SimpleKeyValueSerializationSchema("id", "province"),
new DefaultTopicSelector("flink-sink2"), producerProps).withBatchFlushOnCheckpoint(true))
.name("rocketmq-sink")
.setParallelism(2);
try {
env.execute("rocketmq-flink-example");
} catch (Exception e) {
e.printStackTrace();
}The following configurations are all from the class org.apache.rocketmq.flink.RocketMQConfig.
| NAME | DESCRIPTION | DEFAULT |
|---|---|---|
| nameserver.address | name server address Required | null |
| nameserver.poll.interval | name server poll topic info interval | 30000 |
| brokerserver.heartbeat.interval | broker server heartbeat interval | 30000 |
| producer.group | producer group | UUID.randomUUID().toString() |
| producer.retry.times | producer send messages retry times | 3 |
| producer.timeout | producer send messages timeout | 3000 |
| NAME | DESCRIPTION | DEFAULT |
|---|---|---|
| nameserver.address | name server address Required | null |
| nameserver.poll.interval | name server poll topic info interval | 30000 |
| brokerserver.heartbeat.interval | broker server heartbeat interval | 30000 |
| consumer.group | consumer group Required | null |
| consumer.topic | consumer topic Required | null |
| consumer.tag | consumer topic tag | * |
| consumer.offset.reset.to | what to do when there is no initial offset on the server | latest/earliest/timestamp |
| consumer.offset.from.timestamp | the timestamp when consumer.offset.reset.to=timestamp was set |
System.currentTimeMillis() |
| consumer.offset.persist.interval | auto commit offset interval | 5000 |
| consumer.pull.thread.pool.size | consumer pull thread pool size | 20 |
| consumer.batch.size | consumer messages batch size | 32 |
| consumer.delay.when.message.not.found | the delay time when messages were not found | 10 |
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