http://kafka.apache.org/documentation/

、APIS

Apache Kafka引入一个新的java客户端（在org.apache.kafka.clients 包中），替代老的Scala客户端，
但是为了兼容，将会共存一段时间。
为了减少依赖，这些客户端都有一个独立的jar，而旧的Scala客户端继续与服务端保留在同个包下。

1. The Producer API allows applications to send streams of data to topics in the Kafka cluster.
2. The Consumer API allows applications to read streams of data from topics in the Kafka cluster.
3. The Streams API allows transforming streams of data from input topics to output topics.
4. The Connect API allows implementing connectors that continually pull from some source system or application into Kafka or push from Kafka into some sink system or application.

Kafka有4个核心API：

　　1、Producer API 允许应用程序发送数据流到kafka集群中的topic。

　　2、Consumer API 允许应用程序从kafka集群的topic中读取数据流。

　　3、Streams API 允许从输入topic转换数据流到输出topic。

　　4、Connect API 通过实现连接器（connector），不断地从一些源系统或应用程序中拉取数据到kafka，或从kafka提交数据到宿系统（sink system）或应用程序。

　　Kafka exposes all its functionality over a language independent protocol which has clients available in many programming languages. However only the Java clients are maintained as part of the main Kafka project, the others are available as independent open source projects. A list of non-Java clients is available here.