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Apache Flink

Unified engine for high-throughput, low-latency stream and batch processing

Apache Flink delivers a streaming-first runtime that handles both real-time and batch workloads with exactly-once guarantees, flexible windowing, and native integration with Hadoop ecosystem components.

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Overview

Overview

Apache Flink is a streaming-first framework that also supports batch workloads, providing a single runtime for diverse data processing needs. It offers high throughput while maintaining low event latency, and guarantees exactly-once fault tolerance through checkpointing and natural back‑pressure handling.

Deployment & Integration

Flink runs on Unix‑like systems and integrates seamlessly with the Hadoop ecosystem—YARN, HDFS, HBase, and more. Developers can use fluent Java APIs (or Scala) and leverage built‑in libraries for graph processing, machine learning, and complex event processing. The project ships with externalized connectors for Kafka, JDBC, Elasticsearch, and many other sources, making it adaptable to modern data pipelines.

Audience

Ideal for engineers building real‑time analytics, ETL pipelines, or stateful stream applications that require precise time semantics and robust scalability.

Highlights

Streaming-first runtime with unified batch support
Exactly-once fault tolerance and natural back-pressure
Rich APIs and libraries for graph, ML, and CEP
Seamless integration with Hadoop ecosystem (YARN, HDFS, HBase)

Pros

  • High throughput with low latency
  • Event-time and out-of-order processing
  • Flexible windowing and custom triggers
  • Strong ecosystem and connector library

Considerations

  • Steep learning curve for advanced APIs
  • Requires Java/Scala expertise
  • Resource-intensive for small workloads
  • Operational complexity in large clusters

Managed products teams compare with

When teams consider Apache Flink, these hosted platforms usually appear on the same shortlist.

Aiven for Apache Flink logo

Aiven for Apache Flink

Fully managed Apache Flink service by Aiven.

Amazon Managed Service for Apache Flink logo

Amazon Managed Service for Apache Flink

Serverless Apache Flink for real-time stream processing on AWS.

Azure Stream Analytics logo

Azure Stream Analytics

Serverless real-time analytics with SQL on streams.

Looking for a hosted option? These are the services engineering teams benchmark against before choosing open source.

Fit guide

Great for

  • Real-time analytics on high-velocity data streams
  • Batch ETL jobs needing low-latency results
  • Complex event processing with stateful operators
  • Organizations already using Hadoop/YARN

Not ideal when

  • Simple CRUD applications without streaming needs
  • Environments lacking Java 11+ runtime
  • Teams preferring low-maintenance serverless services
  • Very small datasets where overhead outweighs benefits

How teams use it

Fraud detection in financial transactions

Detect anomalies within seconds using event-time windows and stateful processing.

Clickstream analysis for e‑commerce

Aggregate user actions in real time to power personalized recommendations.

Batch log processing

Generate daily reports from massive log files with exactly-once guarantees.

IoT sensor data aggregation

Combine time-based windows across millions of devices with low latency.

Tech snapshot

Java87%
Scala8%
Python3%
Shell1%
TypeScript1%
HiveQL1%

Tags

scalaflinkpythonsqljavabig-data

Frequently asked questions

Which programming languages are supported?

Primary APIs are available in Java and Scala; Python is supported via PyFlink.

Can Flink run on existing Hadoop clusters?

Yes, Flink integrates with YARN, HDFS, HBase, and other Hadoop components.

What fault‑tolerance guarantees does Flink provide?

Flink offers exactly-once processing guarantees through distributed snapshots.

Is there support for out-of-order event handling?

Flink’s DataStream API supports event-time semantics and out-of-order processing.

How are connectors managed?

Most connectors are externalized into separate Apache projects, such as Kafka, JDBC, and Elasticsearch.

Project at a glance

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LicenseApache-2.0
Repo age11 years old
Last commit2 days ago
Primary languageJava

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