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Apache Flink vs Apache Flume: What are the differences?
Introduction
Apache Flink and Apache Flume are both open-source frameworks used for processing and analyzing data. However, there are significant differences between the two. In this article, we will discuss the key differences between Apache Flink and Apache Flume.
Processing Model: Apache Flink is a stream processing framework designed to handle both batch and real-time data processing. It provides a unified programming model for both batch and stream processing, allowing developers to build complex data pipelines. On the other hand, Apache Flume is a distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of streaming data. It focuses on data ingestion from various sources into a centralized data store or data processing system.
Data Sources: Apache Flink supports various data sources, including message queues, event streams, file systems, and databases. It can consume data from static files, file systems like HDFS, and even external systems like Apache Kafka. In contrast, Apache Flume primarily focuses on collecting data from various sources like web servers, log files, and social media platforms. It is optimized for efficiently collecting and transporting large amounts of data from distributed sources to centralized data stores.
Fault Tolerance: Apache Flink provides strong fault-tolerance guarantees by leveraging its distributed processing model. It ensures that data is processed reliably even in the presence of failures. Flink achieves fault tolerance by leveraging data replication and checkpointing mechanisms. On the other hand, Apache Flume ensures reliability and fault tolerance by using a transactional approach for data collection. It can guarantee the delivery of data to the destination by using reliable and persistent channels.
Event Time Processing: Apache Flink has built-in support for event time processing, allowing developers to handle out-of-order data and achieve accurate results even in the presence of delayed or late data. This feature is crucial for stream processing use cases where data arrives with a timestamp. In contrast, Apache Flume does not have built-in support for event time processing. It primarily focuses on efficient data collection and transportation rather than complex event processing.
Built-in Machine Learning: Apache Flink provides built-in support for machine learning through its FlinkML library. It allows developers to train and deploy machine learning models directly within the Flink runtime. This makes it easy to incorporate machine learning algorithms and predictive analytics into data processing pipelines. On the other hand, Apache Flume does not provide built-in support for machine learning. It is mainly focused on data ingestion and transport.
Stream Processing Throughput: Apache Flink is known for its high-throughput stream processing capabilities. Its optimized runtime and execution engine enable it to process large volumes of data at low latency. Flink achieves high throughput by leveraging parallelism and efficient data distribution strategies. On the other hand, Apache Flume focuses on reliable and scalable data collection rather than high-throughput stream processing.
In summary, Apache Flink is a versatile and powerful stream processing framework that supports both batch and real-time processing, provides fault tolerance guarantees, supports event time processing, and includes built-in machine learning capabilities. On the other hand, Apache Flume is a specialized data collection and transport framework that focuses on efficiently collecting and moving large amounts of data from distributed sources to centralized data stores.
We have a Kafka topic having events of type A and type B. We need to perform an inner join on both type of events using some common field (primary-key). The joined events to be inserted in Elasticsearch.
In usual cases, type A and type B events (with same key) observed to be close upto 15 minutes. But in some cases they may be far from each other, lets say 6 hours. Sometimes event of either of the types never come.
In all cases, we should be able to find joined events instantly after they are joined and not-joined events within 15 minutes.
The first solution that came to me is to use upsert to update ElasticSearch:
- Use the primary-key as ES document id
- Upsert the records to ES as soon as you receive them. As you are using upsert, the 2nd record of the same primary-key will not overwrite the 1st one, but will be merged with it.
Cons: The load on ES will be higher, due to upsert.
To use Flink:
- Create a KeyedDataStream by the primary-key
- In the ProcessFunction, save the first record in a State. At the same time, create a Timer for 15 minutes in the future
- When the 2nd record comes, read the 1st record from the State, merge those two, and send out the result, and clear the State and the Timer if it has not fired
- When the Timer fires, read the 1st record from the State and send out as the output record.
- Have a 2nd Timer of 6 hours (or more) if you are not using Windowing to clean up the State
Pro: if you have already having Flink ingesting this stream. Otherwise, I would just go with the 1st solution.
Please refer "Structured Streaming" feature of Spark. Refer "Stream - Stream Join" at https://spark.apache.org/docs/latest/structured-streaming-programming-guide.html#stream-stream-joins . In short you need to specify "Define watermark delays on both inputs" and "Define a constraint on time across the two inputs"
Pros of Apache Flume
Pros of Apache Flink
- Unified batch and stream processing16
- Easy to use streaming apis8
- Out-of-the box connector to kinesis,s3,hdfs8
- Open Source4
- Low latency2