September 2022
Beginner to intermediate
321 pages
4h 50m
Chinese
Content preview from 语义软件设计
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.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.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.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.
194
｜
第
8
章
•
缓存也需要模型。通常我们不会针对缓存本身建模，因为我们认为缓存只是内
存的反射，而内存已有了建模。在一次解构运动中，一款名为
Coherence
的应
用程序（由
Cameron Purdy
创建并最终卖给了
Oracle
）实现了数据库反转，将“主
要”数据存储移动到内存中，并以持久磁盘层作为辅助存储。在创建索引、物
化视图和去正规化策略中也可以采用这种做法。
•
事件也需要模型。发布了哪些事件，哪些服务需要哪些声明检查来满足事件订
阅者的需求，以及它们将在哪里检索数据？复杂的事件处理系统也会反转数据
库：本质上，它们会存储查询，并让数据在其上流动，当发现查询中的条件与
数据匹配时，就会执行一个函数。
•
流也需要模型。我们将在下面单独介绍，因为可能你对这种模型比较陌生。
建模工作不能仅限于机械地枚举应用程序中的名词，还要在彼此关联的名词之间建
立连接表，并通过列名约定监管开发人员。
8.5
流数据模型
数据流可以对连续流动的一系列事件执行实时分析，而且不必先存储数据。这些数
据的来源多种多样。
常见的流数据有以下几种：
金融
股票代码提供不断变化的金融数据流。追踪器可以实时更新和重新平衡投资组
合，并自动进行交易。
流媒体服务和视频游戏
音乐、电影或有声读物的内容也包括数据流。流中包含有关内容使用情况的元
数据，例如何时暂停、何时倒回、观看的分辨率、接收设备等，我们可以通过
这些原数据改进服务。
网络电子商务点击流
在电子商务网站上，应用程序可以捕获每次点击，甚至每次鼠标悬停，将这些
作为事件，并通过流传输，以作处理，从而了解用户的行为。 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.