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初識Kafka

時間：2021-07-26 16:51:13 阅读：0 評論：0 收藏：0 [點我收藏+]

標簽：多個 png apache 數據集 isp code 圖片分布式 oop

Kafka最早是由LinkedIn公司开发的，作为其自身业务消息处理的基础，后LinkedIn公司将Kafka捐赠给Apache，现在已经成为Apache的一个顶级项目了，Kafka作为一个高吞吐的分布式的消息系统，目前已经被很多公司应用在实际的业务中了，并且与许多数据处理框架相结合，比如Hadoop，Spark等。Kafka 使用 Avro 作爲消息序列化框架

概念：

　　1.什麽是事件流(Steam Event)？

　　　　它是无边界數據集的抽象说法，无边界意味着无限且不断增长，因为随着时间的推移，新数据会不断地到来。最基本的数据流模型，每个节点处理完数据会将数据转发给下游节点。其余特点：数据流是有序的；数据记录是不可变；可重播。

　　2.什麽是流式處理

　　　　持续的从一个无边界的數據集读取数据，然后对它们进行处理并生成结果；是一种编程范式，就像请求和响应范式；请求和响应(延迟最小)；批处理(高延迟和高吞吐量)；

技术圖片

　　3.消息、批次、主題、分區

　　　　Kafka的数据单元被称为消息，消息可以看作是數據庫内的一个记录，消息由字节组成，消息可以有一个可选的元数据(键)，键也是一个字节数组，消息以一种可控的方式写入不同的分区时，会用到键；批次表示为一组消息，这些消息属于同一个分区或者主题，同一批次内的数据可以进行压缩以此来提高对应的效率。

　　　　主题=數據庫中的表，一个主题可以被拆分成任意个分区，因此在无法在整个主题内保证数据的顺序性，分区可以认为是一种数据的冗余。分区也就是一个提交日志。一个主题可以多個服务器组成。

　　技术圖片

　　4.生産者和消費者

　　　　生産者創建消息，消息會被發布到一個特定的主題上，生産者在默認情況下把消息均衡地分布到主題的所有分區上。不會關心被特定寫入到哪個分區上，不過也可以指定寫入特定的分區上。通過消息鍵和分區器來進行實現，分區器會生成一個散列值，並將其映射到特定的分區上。這個可以保證同一個鍵的會被寫入到同一個分區上。

　　　　消費者讀取信息，通過訂閱主題來獲取分區內的消息，會去檢查消息的偏移量來區分已經讀取到的數據。會把讀取到的分區偏移量存儲在kafka或者zookeeper中去。消費者是消費群組的中的一部分，一個分區在同一時間只能保證被一個消費者使用。

技术圖片

標簽：多個 png apache 數據集 isp code 圖片分布式 oop

原文地址：https://www.cnblogs.com/SmartCat994/p/15057815.html

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