Kafka

[chrishyx]

• Kafka maintains feeds of messages in categories called _topics_.
• We'll call processes that publish messages to a Kafka topic _producers_.
• We'll call processes that subscribe to topics and process the feed of published messages _consumers_.
• Kafka is run as a cluster comprised of one or more servers each of which is called a _broker_.

[chrishyx]

• Partition：topic物理上的分组，一个topic可以分为多个partition，每个partition是一个有序的队列。
• Segment：partition物理上由多个segment组成。
• offset：每个partition都由一系列有序的、不可变的消息组成，这些消息被连续的追加到partition中。partition中的每个消息都有一个连续的序列号叫做offset,用于partition唯一标识一条消息.

[chrishyx]

Segment内部结构