Timer on ProcessFunction and KeyedProcessFunction Flink distinguishes between two key notions of time: processing time and event time. Processing time refers to the system time at which an event is processed, whereas event time is explicitly defined or configu…
Stream API (SourceFunction, AbstractSourceFunction and RichSourceFunction) in Flink In Flink's streaming API, there is a critical interface named Function, which extends Serializable: public interface Function extends Serializable { } Nearly all streaming APIs…
Timeline & Search 简介 系统设计中，时间线(timeline)功能是十分常见的，诸如朋友圈，微博，Twitter等社交平台都会涉及到，主要功能就是按时间线看到已经关注的人发送的消息。而搜索功能则是公开社交平台的重要功能。 Pull vs. Push 为了实现时间线的功能，可以采用“推”或者“拉”的手段进行实现。比如某位用户发送了一条消息，那么系统将该消息推送给所有关注者；或者，将消息暂存，等待关注的用户查看的时候，再由用户自己吧消息取出。前者是Push，后者是Pull。 系统读写峰值 以T…