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| <h2 title="Class KafkaIO" class="title">Class KafkaIO</h2> |
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| <pre><a href="../../../../../../org/apache/beam/sdk/annotations/Experimental.html" title="annotation in org.apache.beam.sdk.annotations">@Experimental</a>(<a href="../../../../../../org/apache/beam/sdk/annotations/Experimental.html#value--">value</a>=<a href="../../../../../../org/apache/beam/sdk/annotations/Experimental.Kind.html#SOURCE_SINK">SOURCE_SINK</a>) |
| public class <span class="typeNameLabel">KafkaIO</span> |
| extends java.lang.Object</pre> |
| <div class="block">An unbounded source and a sink for <a href="http://kafka.apache.org/">Kafka</a> topics. |
| |
| <h2>Read from Kafka as <a href="../../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io"><code>UnboundedSource</code></a></h2> |
| |
| <h3>Reading from Kafka topics</h3> |
| |
| <p>KafkaIO source returns unbounded collection of Kafka records as <code>PCollection<KafkaRecord<K, V>></code>. A <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaRecord.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaRecord</code></a> includes basic metadata like |
| topic-partition and offset, along with key and value associated with a Kafka record. |
| |
| <p>Although most applications consume a single topic, the source can be configured to consume |
| multiple topics or even a specific set of <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a>s. |
| |
| <p>To configure a Kafka source, you must specify at the minimum Kafka <tt>bootstrapServers</tt>, |
| one or more topics to consume, and key and value deserializers. For example: |
| |
| <pre><code> |
| pipeline |
| .apply(KafkaIO.<Long, String>read() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("my_topic") // use withTopics(List<String>) to read from multiple topics. |
| .withKeyDeserializer(LongDeserializer.class) |
| .withValueDeserializer(StringDeserializer.class) |
| |
| // Above four are required configuration. returns PCollection<KafkaRecord<Long, String>> |
| |
| // Rest of the settings are optional : |
| |
| // you can further customize KafkaConsumer used to read the records by adding more |
| // settings for ConsumerConfig. e.g : |
| .withConsumerConfigUpdates(ImmutableMap.of("group.id", "my_beam_app_1")) |
| |
| // set event times and watermark based on 'LogAppendTime'. To provide a custom |
| // policy see withTimestampPolicyFactory(). withProcessingTime() is the default. |
| // Use withCreateTime() with topics that have 'CreateTime' timestamps. |
| .withLogAppendTime() |
| |
| // restrict reader to committed messages on Kafka (see method documentation). |
| .withReadCommitted() |
| |
| // offset consumed by the pipeline can be committed back. |
| .commitOffsetsInFinalize() |
| |
| // Specified a serializable function which can determine whether to stop reading from given |
| // TopicPartition during runtime. Note that only {@link ReadFromKafkaDoFn} respect the |
| // signal. |
| .withCheckStopReadingFn(new SerializedFunction<TopicPartition, Boolean>() {}) |
| |
| // finally, if you don't need Kafka metadata, you can drop it.g |
| .withoutMetadata() // PCollection<KV<Long, String>> |
| ) |
| .apply(Values.<String>create()) // PCollection<String> |
| ... |
| </code></pre> |
| |
| <p>Kafka provides deserializers for common types in <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/serialization/package-summary.html?is-external=true"><code>org.apache.kafka.common.serialization</code></a>. In addition to deserializers, Beam runners need <a href="../../../../../../org/apache/beam/sdk/coders/Coder.html" title="class in org.apache.beam.sdk.coders"><code>Coder</code></a> to materialize key and value objects if necessary. In most cases, you don't need to |
| specify <a href="../../../../../../org/apache/beam/sdk/coders/Coder.html" title="class in org.apache.beam.sdk.coders"><code>Coder</code></a> for key and value in the resulting collection because the coders are |
| inferred from deserializer types. However, in cases when coder inference fails, they can be |
| specified explicitly along with deserializers using <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withKeyDeserializerAndCoder-java.lang.Class-org.apache.beam.sdk.coders.Coder-"><code>KafkaIO.Read.withKeyDeserializerAndCoder(Class, Coder)</code></a> and <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withValueDeserializerAndCoder-java.lang.Class-org.apache.beam.sdk.coders.Coder-"><code>KafkaIO.Read.withValueDeserializerAndCoder(Class, Coder)</code></a>. Note that Kafka messages are interpreted using |
| key and value <i>deserializers</i>. |
| |
| <h3>Read From Kafka Dynamically</h3> |
| |
| For a given kafka bootstrap_server, KafkaIO is also able to detect and read from available <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a> dynamically and stop reading from un. KafkaIO uses <code>WatchKafkaTopicPartitionDoFn</code> to emit any new added <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a> and uses <code>ReadFromKafkaDoFn</code> to read from each <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaSourceDescriptor.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaSourceDescriptor</code></a>. Dynamic read is able to solve |
| 2 scenarios: |
| |
| <ul> |
| <li>Certain topic or partition is added/deleted. |
| <li>Certain topic or partition is added, then removed but added back again |
| </ul> |
| |
| Within providing <code>checkStopReadingFn</code>, there are 2 more cases that dynamic read can handle: |
| |
| <ul> |
| <li>Certain topic or partition is stopped |
| <li>Certain topic or partition is added, then stopped but added back again |
| </ul> |
| |
| Race conditions may happen under 2 supported cases: |
| |
| <ul> |
| <li>A TopicPartition is removed, but added backed again |
| <li>A TopicPartition is stopped, then want to read it again |
| </ul> |
| |
| When race condition happens, it will result in the stopped/removed TopicPartition failing to be |
| emitted to ReadFromKafkaDoFn again. Or ReadFromKafkaDoFn will output replicated records. The |
| major cause for such race condition is that both <code>WatchKafkaTopicPartitionDoFn</code> and <code>ReadFromKafkaDoFn</code> react to the signal from removed/stopped <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a> but we cannot |
| guarantee that both DoFns perform related actions at the same time. |
| |
| <p>Here is one example for failing to emit new added <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a>: |
| |
| <ul> |
| <li>A <code>WatchKafkaTopicPartitionDoFn</code> is configured with updating the current tracking set |
| every 1 hour. |
| <li>One TopicPartition A is tracked by the <code>WatchKafkaTopicPartitionDoFn</code> at 10:00AM and |
| <code>ReadFromKafkaDoFn</code> starts to read from TopicPartition A immediately. |
| <li>At 10:30AM, the <code>WatchKafkaTopicPartitionDoFn</code> notices that the <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/TopicPartition.html?is-external=true" title="class or interface in org.apache.kafka.common"><code>TopicPartition</code></a> has been stopped/removed, so it stops reading from it and returns <code>ProcessContinuation.stop()</code>. |
| <li>At 10:45 the pipeline author wants to read from TopicPartition A again. |
| <li>At 11:00AM when <code>WatchKafkaTopicPartitionDoFn</code> is invoked by firing timer, it doesn’t |
| know that TopicPartition A has been stopped/removed. All it knows is that TopicPartition A |
| is still an active TopicPartition and it will not emit TopicPartition A again. |
| </ul> |
| |
| Another race condition example for producing duplicate records: |
| |
| <ul> |
| <li>At 10:00AM, <code>ReadFromKafkaDoFn</code> is processing TopicPartition A |
| <li>At 10:05AM, <code>ReadFromKafkaDoFn</code> starts to process other TopicPartitions(sdf-initiated |
| checkpoint or runner-issued checkpoint happens) |
| <li>At 10:10AM, <code>WatchKafkaTopicPartitionDoFn</code> knows that TopicPartition A is |
| stopped/removed |
| <li>At 10:15AM, <code>WatchKafkaTopicPartitionDoFn</code> knows that TopicPartition A is added again |
| and emits TopicPartition A again |
| <li>At 10:20AM, <code>ReadFromKafkaDoFn</code> starts to process resumed TopicPartition A but at the |
| same time <code>ReadFromKafkaDoFn</code> is also processing the new emitted TopicPartitionA. |
| </ul> |
| |
| For more design details, please refer to |
| https://docs.google.com/document/d/1FU3GxVRetHPLVizP3Mdv6mP5tpjZ3fd99qNjUI5DT5k/. To enable |
| dynamic read, you can write a pipeline like: |
| |
| <pre><code> |
| pipeline |
| .apply(KafkaIO.<Long, String>read() |
| // Configure the dynamic read with 1 hour, where the pipeline will look into available |
| // TopicPartitions and emit new added ones every 1 hour. |
| .withDynamicRead(Duration.standardHours(1)) |
| .withCheckStopReadingFn(new SerializedFunction<TopicPartition, Boolean>() {}) |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withKeyDeserializer(LongDeserializer.class) |
| .withValueDeserializer(StringDeserializer.class) |
| ) |
| .apply(Values.<String>create()) // PCollection<String> |
| ... |
| </code></pre> |
| |
| <h3>Partition Assignment and Checkpointing</h3> |
| |
| The Kafka partitions are evenly distributed among splits (workers). |
| |
| <p>Checkpointing is fully supported and each split can resume from previous checkpoint (to the |
| extent supported by runner). See <code>KafkaUnboundedSource.split(int, PipelineOptions)</code> for |
| more details on splits and checkpoint support. |
| |
| <p>When the pipeline starts for the first time, or without any checkpoint, the source starts |
| consuming from the <em>latest</em> offsets. You can override this behavior to consume from the |
| beginning by setting properties appropriately in <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/consumer/ConsumerConfig.html?is-external=true" title="class or interface in org.apache.kafka.clients.consumer"><code>ConsumerConfig</code></a>, through <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withConsumerConfigUpdates-java.util.Map-"><code>KafkaIO.Read.withConsumerConfigUpdates(Map)</code></a>. You can also enable offset auto_commit in Kafka to resume |
| from last committed. |
| |
| <p>In summary, KafkaIO.read follows below sequence to set initial offset:<br> |
| 1. <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaCheckpointMark.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaCheckpointMark</code></a> provided by runner;<br> |
| 2. Consumer offset stored in Kafka when <code>ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG = true</code>; |
| <br> |
| 3. Start from <em>latest</em> offset by default; |
| |
| <p>Seek to initial offset is a blocking operation in Kafka API, which can block forever for |
| certain versions of Kafka client library. This is resolved by <a |
| href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-266%3A+Fix+consumer+indefinite+blocking+behavior">KIP-266</a> |
| which provides `default.api.timeout.ms` consumer config setting to control such timeouts. |
| KafkaIO.read implements timeout itself, to not to block forever in case older Kafka client is |
| used. It does recognize `default.api.timeout.ms` setting and will honor the timeout value if it |
| is passes in consumer config. |
| |
| <h3>Use Avro schema with Confluent Schema Registry</h3> |
| |
| <p>If you want to deserialize the keys and/or values based on a schema available in Confluent |
| Schema Registry, KafkaIO can fetch this schema from a specified Schema Registry URL and use it |
| for deserialization. A <a href="../../../../../../org/apache/beam/sdk/coders/Coder.html" title="class in org.apache.beam.sdk.coders"><code>Coder</code></a> will be inferred automatically based on the respective |
| <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/serialization/Deserializer.html?is-external=true" title="class or interface in org.apache.kafka.common.serialization"><code>Deserializer</code></a>. |
| |
| <p>For an Avro schema it will return a <a href="../../../../../../org/apache/beam/sdk/values/PCollection.html" title="class in org.apache.beam.sdk.values"><code>PCollection</code></a> of <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaRecord.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaRecord</code></a>s where key |
| and/or value will be typed as <a href="https://static.javadoc.io/org.apache.avro/avro/1.8.2/org/apache/avro/generic/GenericRecord.html?is-external=true" title="class or interface in org.apache.avro.generic"><code>GenericRecord</code></a>. In this case, users |
| don't need to specify key or/and value deserializers and coders since they will be set to <code>KafkaAvroDeserializer</code> and <a href="../../../../../../org/apache/beam/sdk/coders/AvroCoder.html" title="class in org.apache.beam.sdk.coders"><code>AvroCoder</code></a> by default accordingly. |
| |
| <p>For example, below topic values are serialized with Avro schema stored in Schema Registry, |
| keys are typed as <code>Long</code>: |
| |
| <pre><code> |
| PCollection<KafkaRecord<Long, GenericRecord>> input = pipeline |
| .apply(KafkaIO.<Long, GenericRecord>read() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("my_topic") |
| .withKeyDeserializer(LongDeserializer.class) |
| // Use Confluent Schema Registry, specify schema registry URL and value subject |
| .withValueDeserializer( |
| ConfluentSchemaRegistryDeserializerProvider.of("http://localhost:8081", "my_topic-value")) |
| ... |
| </code></pre> |
| |
| <p>You can also pass properties to the schema registry client allowing you to configure |
| authentication |
| |
| <pre><code> |
| ImmutableMap<String, Object> csrConfig = |
| ImmutableMap.<String, Object>builder() |
| .put(AbstractKafkaAvroSerDeConfig.BASIC_AUTH_CREDENTIALS_SOURCE,"USER_INFO") |
| .put(AbstractKafkaAvroSerDeConfig.USER_INFO_CONFIG,"<username>:<password>") |
| .build(); |
| |
| PCollection<KafkaRecord<Long, GenericRecord>> input = pipeline |
| .apply(KafkaIO.<Long, GenericRecord>read() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("my_topic") |
| .withKeyDeserializer(LongDeserializer.class) |
| // Use Confluent Schema Registry, specify schema registry URL, value subject and schema registry client configuration |
| .withValueDeserializer( |
| ConfluentSchemaRegistryDeserializerProvider.of("https://localhost:8081", "my_topic-value", null, csrConfig)) |
| ... |
| </code></pre> |
| |
| <h2>Read from Kafka as a <a href="../../../../../../org/apache/beam/sdk/transforms/DoFn.html" title="class in org.apache.beam.sdk.transforms"><code>DoFn</code></a></h2> |
| |
| <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> is the <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> that takes a PCollection of <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaSourceDescriptor.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaSourceDescriptor</code></a> as input and outputs a PCollection of <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaRecord.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaRecord</code></a>. The core |
| implementation is based on <code>SplittableDoFn</code>. For more details about the concept of <code>SplittableDoFn</code>, please refer to the <a |
| href="https://beam.apache.org/blog/splittable-do-fn/">blog post</a> and <a |
| href="https://s.apache.org/beam-fn-api">design doc</a>. The major difference from <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Read</code></a> is, <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> doesn't require source descriptions(e.g., <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getTopicPartitions--"><code>KafkaIO.Read.getTopicPartitions()</code></a>, <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getTopics--"><code>KafkaIO.Read.getTopics()</code></a>, <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getStartReadTime--"><code>KafkaIO.Read.getStartReadTime()</code></a>, etc.) during the pipeline construction time. Instead, the |
| pipeline can populate these source descriptions during runtime. For example, the pipeline can |
| query Kafka topics from a BigQuery table and read these topics via <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a>. |
| |
| <h3>Common Kafka Consumer Configurations</h3> |
| |
| <p>Most Kafka consumer configurations are similar to <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Read</code></a>: |
| |
| <ul> |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getConsumerConfig--"><code>KafkaIO.ReadSourceDescriptors.getConsumerConfig()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getConsumerConfig--"><code>KafkaIO.Read.getConsumerConfig()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getConsumerFactoryFn--"><code>KafkaIO.ReadSourceDescriptors.getConsumerFactoryFn()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getConsumerFactoryFn--"><code>KafkaIO.Read.getConsumerFactoryFn()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getOffsetConsumerConfig--"><code>KafkaIO.ReadSourceDescriptors.getOffsetConsumerConfig()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getOffsetConsumerConfig--"><code>KafkaIO.Read.getOffsetConsumerConfig()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getKeyCoder--"><code>KafkaIO.ReadSourceDescriptors.getKeyCoder()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getKeyCoder--"><code>KafkaIO.Read.getKeyCoder()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getValueCoder--"><code>KafkaIO.ReadSourceDescriptors.getValueCoder()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getValueCoder--"><code>KafkaIO.Read.getValueCoder()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getKeyDeserializerProvider--"><code>KafkaIO.ReadSourceDescriptors.getKeyDeserializerProvider()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getKeyDeserializerProvider--"><code>KafkaIO.Read.getKeyDeserializerProvider()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#getValueDeserializerProvider--"><code>KafkaIO.ReadSourceDescriptors.getValueDeserializerProvider()</code></a> is the same as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#getValueDeserializerProvider--"><code>KafkaIO.Read.getValueDeserializerProvider()</code></a>. |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#isCommitOffsetEnabled--"><code>KafkaIO.ReadSourceDescriptors.isCommitOffsetEnabled()</code></a> has the same meaning as <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#isCommitOffsetsInFinalizeEnabled--"><code>KafkaIO.Read.isCommitOffsetsInFinalizeEnabled()</code></a>. |
| </ul> |
| |
| <p>For example, to create a basic <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> transform: |
| |
| <pre><code> |
| pipeline |
| .apply(Create.of(KafkaSourceDescriptor.of(new TopicPartition("topic", 1))) |
| .apply(KafkaIO.readAll() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withKeyDeserializer(LongDeserializer.class). |
| .withValueDeserializer(StringDeserializer.class)); |
| </code></pre> |
| |
| Note that the <code>bootstrapServers</code> can also be populated from the <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaSourceDescriptor.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaSourceDescriptor</code></a>: |
| |
| <pre><code> |
| pipeline |
| .apply(Create.of( |
| KafkaSourceDescriptor.of( |
| new TopicPartition("topic", 1), |
| null, |
| null, |
| ImmutableList.of("broker_1:9092", "broker_2:9092")) |
| .apply(KafkaIO.readAll() |
| .withKeyDeserializer(LongDeserializer.class). |
| .withValueDeserializer(StringDeserializer.class)); |
| </code></pre> |
| |
| <h3>Configurations of <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a></h3> |
| |
| <p>Except configurations of Kafka Consumer, there are some other configurations which are related |
| to processing records. |
| |
| <p><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#commitOffsets--"><code>KafkaIO.ReadSourceDescriptors.commitOffsets()</code></a> enables committing offset after processing the |
| record. Note that if the <code>isolation.level</code> is set to "read_committed" or <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/consumer/ConsumerConfig.html?is-external=true#ENABLE_AUTO_COMMIT_CONFIG" title="class or interface in org.apache.kafka.clients.consumer"><code>ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG</code></a> is set in the consumer config, the <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#commitOffsets--"><code>KafkaIO.ReadSourceDescriptors.commitOffsets()</code></a> will be ignored. |
| |
| <p><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#withExtractOutputTimestampFn-org.apache.beam.sdk.transforms.SerializableFunction-"><code>KafkaIO.ReadSourceDescriptors.withExtractOutputTimestampFn(SerializableFunction)</code></a> is used to |
| compute the <code>output timestamp</code> for a given <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaRecord.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaRecord</code></a> and controls the watermark |
| advancement. There are three built-in types: |
| |
| <ul> |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#withProcessingTime--"><code>KafkaIO.ReadSourceDescriptors.withProcessingTime()</code></a> |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#withCreateTime--"><code>KafkaIO.ReadSourceDescriptors.withCreateTime()</code></a> |
| <li><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#withLogAppendTime--"><code>KafkaIO.ReadSourceDescriptors.withLogAppendTime()</code></a> |
| </ul> |
| |
| <p>For example, to create a <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> with this additional configuration: |
| |
| <pre><code> |
| pipeline |
| .apply(Create.of( |
| KafkaSourceDescriptor.of( |
| new TopicPartition("topic", 1), |
| null, |
| null, |
| ImmutableList.of("broker_1:9092", "broker_2:9092")) |
| .apply(KafkaIO.readAll() |
| .withKeyDeserializer(LongDeserializer.class). |
| .withValueDeserializer(StringDeserializer.class) |
| .withProcessingTime() |
| .commitOffsets()); |
| </code></pre> |
| |
| <h3>Writing to Kafka</h3> |
| |
| <p>KafkaIO sink supports writing key-value pairs to a Kafka topic. Users can also write just the |
| values or native Kafka producer records using <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/producer/ProducerRecord.html?is-external=true" title="class or interface in org.apache.kafka.clients.producer"><code>ProducerRecord</code></a>. To configure a Kafka sink, you must specify at |
| the minimum Kafka <tt>bootstrapServers</tt>, the topic to write to, and key and value |
| serializers. For example: |
| |
| <pre><code> |
| PCollection<KV<Long, String>> kvColl = ...; |
| kvColl.apply(KafkaIO.<Long, String>write() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("results") |
| |
| .withKeySerializer(LongSerializer.class) |
| .withValueSerializer(StringSerializer.class) |
| |
| // You can further customize KafkaProducer used to write the records by adding more |
| // settings for ProducerConfig. e.g, to enable compression : |
| .withProducerConfigUpdates(ImmutableMap.of("compression.type", "gzip")) |
| |
| // You set publish timestamp for the Kafka records. |
| .withInputTimestamp() // element timestamp is used while publishing to Kafka |
| // or you can also set a custom timestamp with a function. |
| .withPublishTimestampFunction((elem, elemTs) -> ...) |
| |
| // Optionally enable exactly-once sink (on supported runners). See JavaDoc for withEOS(). |
| .withEOS(20, "eos-sink-group-id"); |
| ); |
| </code></pre> |
| |
| <p>To produce Avro values you can use class <code>KafkaAvroSerializer</code>. To make this class work with <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#write--"><code>write()</code></a> and method withValueSerializer() make sure to erase the generic types by casting |
| to (Class) as shown in the following example: |
| |
| <pre><code> |
| KafkaIO.<Long, String>write() |
| ... |
| .withValueSerializer((Class)KafkaAvroSerializer.class) |
| .withProducerConfigUpdates( <Map with schema registry configuration details> ) |
| ... |
| </code></pre> |
| |
| <p>Often you might want to write just values without any keys to Kafka. Use <code>values()</code> to |
| write records with default empty(null) key: |
| |
| <pre><code> |
| PCollection<String> strings = ...; |
| strings.apply(KafkaIO.<Void, String>write() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("results") |
| .withValueSerializer(StringSerializer.class) // just need serializer for value |
| .values() |
| ); |
| </code></pre> |
| |
| <p>Also, if you want to write Kafka <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/producer/ProducerRecord.html?is-external=true" title="class or interface in org.apache.kafka.clients.producer"><code>ProducerRecord</code></a> then you should use <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#writeRecords--"><code>writeRecords()</code></a>: |
| |
| <pre><code> |
| PCollection<ProducerRecord<Long, String>> records = ...; |
| records.apply(KafkaIO.<Long, String>writeRecords() |
| .withBootstrapServers("broker_1:9092,broker_2:9092") |
| .withTopic("results") |
| .withKeySerializer(LongSerializer.class) |
| .withValueSerializer(StringSerializer.class) |
| ); |
| </code></pre> |
| |
| <h3>Advanced Kafka Configuration</h3> |
| |
| KafkaIO allows setting most of the properties in <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/consumer/ConsumerConfig.html?is-external=true" title="class or interface in org.apache.kafka.clients.consumer"><code>ConsumerConfig</code></a> for source or in <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/clients/producer/ProducerConfig.html?is-external=true" title="class or interface in org.apache.kafka.clients.producer"><code>ProducerConfig</code></a> for sink. E.g. if you would like to enable offset <em>auto commit</em> (for |
| external monitoring or other purposes), you can set <tt>"group.id"</tt>, |
| <tt>"enable.auto.commit"</tt>, etc. |
| |
| <h3>Event Timestamps and Watermark</h3> |
| |
| By default, record timestamp (event time) is set to processing time in KafkaIO reader and source |
| watermark is current wall time. If a topic has Kafka server-side ingestion timestamp enabled |
| ('LogAppendTime'), it can enabled with <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withLogAppendTime--"><code>KafkaIO.Read.withLogAppendTime()</code></a>. A custom timestamp |
| policy can be provided by implementing <a href="../../../../../../org/apache/beam/sdk/io/kafka/TimestampPolicyFactory.html" title="interface in org.apache.beam.sdk.io.kafka"><code>TimestampPolicyFactory</code></a>. See <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withTimestampPolicyFactory-org.apache.beam.sdk.io.kafka.TimestampPolicyFactory-"><code>KafkaIO.Read.withTimestampPolicyFactory(TimestampPolicyFactory)</code></a> for more information. |
| |
| <h3>Supported Kafka Client Versions</h3> |
| |
| KafkaIO relies on <i>kafka-clients</i> for all its interactions with the Kafka cluster. |
| <i>kafka-clients</i> versions 0.10.1 and newer are supported at runtime. The older versions 0.9.x |
| - 0.10.0.0 are also supported, but are deprecated and likely be removed in near future. Please |
| ensure that the version included with the application is compatible with the version of your |
| Kafka cluster. Kafka client usually fails to initialize with a clear error message in case of |
| incompatibility.</div> |
| </li> |
| </ul> |
| </div> |
| <div class="summary"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ======== NESTED CLASS SUMMARY ======== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="nested.class.summary"> |
| <!-- --> |
| </a> |
| <h3>Nested Class Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Nested Class Summary table, listing nested classes, and an explanation"> |
| <caption><span>Nested Classes</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Class and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Read</a><<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="type parameter in KafkaIO.Read">K</a>,<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="type parameter in KafkaIO.Read">V</a>></span></code> |
| <div class="block">A <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> to read from Kafka topics.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.ReadSourceDescriptors</a><<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="type parameter in KafkaIO.ReadSourceDescriptors">K</a>,<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="type parameter in KafkaIO.ReadSourceDescriptors">V</a>></span></code> |
| <div class="block">A <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> to read from <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaSourceDescriptor.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaSourceDescriptor</code></a>.</div> |
| </td> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.TypedWithoutMetadata.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.TypedWithoutMetadata</a><<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.TypedWithoutMetadata.html" title="type parameter in KafkaIO.TypedWithoutMetadata">K</a>,<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.TypedWithoutMetadata.html" title="type parameter in KafkaIO.TypedWithoutMetadata">V</a>></span></code> |
| <div class="block">A <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> to read from Kafka topics.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Write</a><<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="type parameter in KafkaIO.Write">K</a>,<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="type parameter in KafkaIO.Write">V</a>></span></code> |
| <div class="block">A <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> to write to a Kafka topic with KVs .</div> |
| </td> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.WriteRecords</a><<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="type parameter in KafkaIO.WriteRecords">K</a>,<a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="type parameter in KafkaIO.WriteRecords">V</a>></span></code> |
| <div class="block">A <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a> to write to a Kafka topic with ProducerRecord's.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| <!-- ========== METHOD SUMMARY =========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="method.summary"> |
| <!-- --> |
| </a> |
| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t1" class="tableTab"><span><a href="javascript:show(1);">Static Methods</a></span><span class="tabEnd"> </span></span><span id="t4" class="tableTab"><span><a href="javascript:show(8);">Concrete Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Read</a><K,V></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#read--">read</a></span>()</code> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Read</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>static <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Read</a><byte[],byte[]></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#readBytes--">readBytes</a></span>()</code> |
| <div class="block">A specific instance of uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#read--"><code>read()</code></a> where key and values are bytes.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.ReadSourceDescriptors</a><K,V></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#readSourceDescriptors--">readSourceDescriptors</a></span>()</code> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Write</a><K,V></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#write--">write</a></span>()</code> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Write</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.WriteRecords</a><K,V></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#writeRecords--">writeRecords</a></span>()</code> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.WriteRecords</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>.</div> |
| </td> |
| </tr> |
| </table> |
| <ul class="blockList"> |
| <li class="blockList"><a name="methods.inherited.from.class.java.lang.Object"> |
| <!-- --> |
| </a> |
| <h3>Methods inherited from class java.lang.Object</h3> |
| <code>clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ============ METHOD DETAIL ========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="method.detail"> |
| <!-- --> |
| </a> |
| <h3>Method Detail</h3> |
| <a name="readBytes--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>readBytes</h4> |
| <pre>public static <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Read</a><byte[],byte[]> readBytes()</pre> |
| <div class="block">A specific instance of uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.html#read--"><code>read()</code></a> where key and values are bytes. See |
| #read().</div> |
| </li> |
| </ul> |
| <a name="read--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>read</h4> |
| <pre>public static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Read</a><K,V> read()</pre> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Read</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>. Before use, basic Kafka configuration |
| should set with <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withBootstrapServers-java.lang.String-"><code>KafkaIO.Read.withBootstrapServers(String)</code></a> and <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html#withTopics-java.util.List-"><code>KafkaIO.Read.withTopics(List)</code></a>. |
| Other optional settings include key and value <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/serialization/Deserializer.html?is-external=true" title="class or interface in org.apache.kafka.common.serialization"><code>Deserializer</code></a>s, custom timestamp, |
| watermark functions.</div> |
| </li> |
| </ul> |
| <a name="readSourceDescriptors--"> |
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| <h4>readSourceDescriptors</h4> |
| <pre>public static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.ReadSourceDescriptors</a><K,V> readSourceDescriptors()</pre> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>. Different from |
| <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Read.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Read</code></a>, setting up <code>topics</code> and <code>bootstrapServers</code> is not required during |
| construction time. But the <code>bootstrapServers</code> still can be configured <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html#withBootstrapServers-java.lang.String-"><code>KafkaIO.ReadSourceDescriptors.withBootstrapServers(String)</code></a>. Please refer to <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.ReadSourceDescriptors.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.ReadSourceDescriptors</code></a> for more details.</div> |
| </li> |
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| <h4>write</h4> |
| <pre>public static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.Write</a><K,V> write()</pre> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.Write</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>. Before use, Kafka configuration |
| should be set with <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html#withBootstrapServers-java.lang.String-"><code>KafkaIO.Write.withBootstrapServers(String)</code></a> and <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.Write.html#withTopic-java.lang.String-"><code>KafkaIO.Write.withTopic(java.lang.String)</code></a> along |
| with <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/serialization/Deserializer.html?is-external=true" title="class or interface in org.apache.kafka.common.serialization"><code>Deserializer</code></a>s for (optional) key and values.</div> |
| </li> |
| </ul> |
| <a name="writeRecords--"> |
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| <ul class="blockListLast"> |
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| <h4>writeRecords</h4> |
| <pre>public static <K,V> <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="class in org.apache.beam.sdk.io.kafka">KafkaIO.WriteRecords</a><K,V> writeRecords()</pre> |
| <div class="block">Creates an uninitialized <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html" title="class in org.apache.beam.sdk.io.kafka"><code>KafkaIO.WriteRecords</code></a> <a href="../../../../../../org/apache/beam/sdk/transforms/PTransform.html" title="class in org.apache.beam.sdk.transforms"><code>PTransform</code></a>. Before use, Kafka |
| configuration should be set with <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html#withBootstrapServers-java.lang.String-"><code>KafkaIO.WriteRecords.withBootstrapServers(String)</code></a> and <a href="../../../../../../org/apache/beam/sdk/io/kafka/KafkaIO.WriteRecords.html#withTopic-java.lang.String-"><code>KafkaIO.WriteRecords.withTopic(java.lang.String)</code></a> along with <a href="https://static.javadoc.io/org.apache.kafka/kafka-clients/2.4.1/org/apache/kafka/common/serialization/Deserializer.html?is-external=true" title="class or interface in org.apache.kafka.common.serialization"><code>Deserializer</code></a>s for (optional) key and values.</div> |
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