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Overview

docs/content/docs/connectors/datastream/overview.md

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DataStream Connectors

Predefined Sources and Sinks

A few basic data sources and sinks are built into Flink and are always available. The [predefined data sources]({{< ref "docs/dev/datastream/overview" >}}#data-sources) include reading from files, directories, and sockets, and ingesting data from collections and iterators. The [predefined data sinks]({{< ref "docs/dev/datastream/overview" >}}#data-sinks) support writing to files, to stdout and stderr, and to sockets.

Connectors provide code for interfacing with various third-party systems. Currently these systems are supported as part of the Apache Flink project:

  • [Apache Kafka]({{< ref "docs/connectors/datastream/kafka" >}}) (source/sink)
  • [Apache Cassandra]({{< ref "docs/connectors/datastream/cassandra" >}}) (source/sink)
  • [Amazon DynamoDB]({{< ref "docs/connectors/datastream/dynamodb" >}}) (sink)
  • [Amazon Kinesis Data Streams]({{< ref "docs/connectors/datastream/kinesis" >}}) (source/sink)
  • [Amazon Kinesis Data Firehose]({{< ref "docs/connectors/datastream/firehose" >}}) (sink)
  • [DataGen]({{< ref "docs/connectors/datastream/datagen" >}}) (source)
  • [Elasticsearch]({{< ref "docs/connectors/datastream/elasticsearch" >}}) (sink)
  • [Opensearch]({{< ref "docs/connectors/datastream/opensearch" >}}) (sink)
  • [FileSystem]({{< ref "docs/connectors/datastream/filesystem" >}}) (source/sink)
  • [RabbitMQ]({{< ref "docs/connectors/datastream/rabbitmq" >}}) (source/sink)
  • [Google PubSub]({{< ref "docs/connectors/datastream/pubsub" >}}) (source/sink)
  • [Hybrid Source]({{< ref "docs/connectors/datastream/hybridsource" >}}) (source)
  • [Apache Pulsar]({{< ref "docs/connectors/datastream/pulsar" >}}) (source)
  • [JDBC]({{< ref "docs/connectors/datastream/jdbc" >}}) (sink)
  • [MongoDB]({{< ref "docs/connectors/datastream/mongodb" >}}) (source/sink)
  • [Prometheus]({{< ref "docs/connectors/datastream/prometheus" >}}) (sink)

Keep in mind that to use one of these connectors in an application, additional third party components are usually required, e.g. servers for the data stores or message queues. Note also that while the streaming connectors listed in this section are part of the Flink project and are included in source releases, they are not included in the binary distributions. Further instructions can be found in the corresponding subsections.

{{< hint info >}} Because the flink-connector-base dependency has been bundled in flink-dist, these externalized connectors start to stop bundling the flink-connector-base dependency. See more in <a href="https://issues.apache.org/jira/browse/FLINK-30400">FLINK-30400</a>. If you need to run examples locally, make sure that the flink-connector-base dependency is provided and can be found in your own classpath. {{< /hint >}}

Connectors in Apache Bahir

Additional streaming connectors for Flink are being released through Apache Bahir, including:

Data Enrichment via Async I/O

Using a connector isn't the only way to get data in and out of Flink. One common pattern is to query an external database or web service in a Map or FlatMap in order to enrich the primary datastream. Flink offers an API for [Asynchronous I/O]({{< ref "docs/dev/datastream/operators/asyncio" >}}) to make it easier to do this kind of enrichment efficiently and robustly.

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