1.linux下连接redis后命令
192.168.217.128:6379> help @pubsub
PSUBSCRIBE pattern [pattern ...]
summary: Listen for messages published to channels matching the given patterns
PUBLISH channel message
summary: Post a message to a channel
PUBSUB subcommand [argument [argument ...]]
summary: Inspect the state of the Pub/Sub subsystem
PUNSUBSCRIBE [pattern [pattern ...]]
summary: Stop listening for messages posted to channels matching the given patterns
SUBSCRIBE channel [channel ...]
summary: Listen for messages published to the given channels
UNSUBSCRIBE [channel [channel ...]]
summary: Stop listening for messages posted to the given channels
2.发布订阅示例
先开启订阅channel消息，待向channel发布消息时，订阅者(支持多个)才能正确接收消息。
3.实时和历史消息怎么查看？
上图存在弊端，当发布消息客户端发布消息后，还没有来得及放到sorted set中保存起来，就宕机了。这时候，查看3天之内消息的时候，就发现消息丢失了。怎么解决呢？见下图：
建了两个redis，一个负责发布消息，一个负责订阅消息。实时发送的消息客户端直接接收。3天之内的消息，负责订阅消息的redis接收并保存到sorted set中。更久的消息，通过kafka等消息中间件，最终保存到数据库中。