redis的发布订阅就是一种消息队列么

Question

一直对消息队列的概念很模糊，目前理解消息队列是异步实现需求的方法。
这就产生了一个疑问：一般的消息队列，取消息是客户端主动去取么？还是队列主动推送给客户端？如果是客户端主动取，那取消息的线程就需要一直等待么？
redis的发布订阅意思是不是就是发布者发布消息后订阅者能马上得到？可以看做一种消息队列的实现？

Answer 1

I have used a message queue server gearman
His mechanism is:
1. The queue provides monitoring services and supports clients to add message queues, similar to the concept of functions
2. The queue sub-function provides queue services
3. The queue actively requests the client to execute the corresponding function queue work process