March 2022
Intermediate to advanced
522 pages
13h 52m
Chinese
Content preview from Python语言及其应用（第2版）
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298
｜
第
17
章
•
另一种常见模式是
推送
（
push
），或者
扇出
（
fanout
）：将数据发送给进程池中任意可用
的工作进程。比如位于负载均衡器之后的
We
b
服务器。
•
与推送相反的模式是
拉取
（
pull
）
，或者
扇入
（
fanin
）：从一个或多个资源处接收数据。
比如从多个进程处获取文本消息并将其写入单个日志文件的日志记录程序（
logger
）。
•
还有一种与无线电或电视广播类似的模式：
发布
–
订阅
（
publish-subscribe
或
pub-sub
）。
在该模式中，发布者会发送数据。对于简单的“发布
–
订阅”系统
，所有的订阅者都会
接收到副本。订阅者大多能够指定自己感兴趣的数据类型（通常称为
话题
），发布者只
向其发送此类数据。因此，与推送模式不同，多个订阅者可能会收到特定的数据。如果
某主题没有订阅者，则该数据将被忽略。
下面先来看几个“请求
–
回应”模式和“发布
–
订阅”模式的例子。
17.3
“
请求
–
回应
”
模式
这是最为人熟知的模式。你向
DNS
、
Web
或电子邮件服务器发出请求，服务器回应请求，
或是告知你是否存在问题。
本书已经展示过如何使用
UDP
或
TCP
创建一些基本请求
，但是在套接字层面构建网络应
用的难度太大。来看看
ZeroMQ
能不能帮上忙。
17.3.1 ZeroMQ
ZeroMQ
是一个库，不是服务器。
ZeroMQ
有时被描述为
增强版套接字
（
socket on steroid
）。
ZeroMQ
套接字实现了你希望普通套接字所具有的功能：
•
交换完整的消息；
•
重建连接；
•
当发送方和接收方的节奏不一致时，对数据进行缓冲。 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.