January 2023
Intermediate to advanced
458 pages
14h 16m
Chinese
Content preview from 可编程网络自动化
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数据格式与数据模型
｜
125
据时，希望它是一个字符串，但实际上得到的是布尔值，这很有可能造成软件产生错误的
结果，甚至是崩溃。
数据模型是定义以某种数据格式（如
Y
AML
）存储的数据的结构和内容的一种方式。使用
数据模型，我们可以明确声明
Y
AML
文档中的数据必须是“键
–
值”列表，并且每个值都
必须是字符串。
遗憾的是，
Y
AML
并没有提供任何内建机制来描述或强制数据模型。不过好在还有第三方
工具（
Kwalify
就是其中之一）
。这就是
YAML
非常适合人机交互，但不一定适合机器与机
器交互的原因之一。
YAML
被视为
JSON
的超集，本章稍后会讨论
JSON
这种格式。从理论上
讲，这意味着用于验证
JSON
模式（
JSON
文档的数据模型）的工具也可以
验证
YAML
文档。
接下来要介绍的另一种数据格式
XML
所提供的一些特性和功能使其更适合于机器与机器
的交互。
5.3
XML
如上一节所述，虽然
YAML
适合于人机交互，但是当软件元素之间需要相互通信时，诸如
XML
和
JSON
之类的其他格式往往会受到青睐
，作为数据描述之选。本节将介绍
XML
及
其为何适合此类用例。
XML
在各种工具和语言中享有广泛的支持，比如
Python
的
LXML
库。事实
上，
XML
定义本身也伴随着模式约束、转换和高级查询等各种相关的定义。
因此，本节只涉及
XML
。你可以自己去尝试一些相关的工具和格式。
5.3.1
XML
基础
XML
与
YAML
有一些相似之处。例如，二者都有内在的层次结构。我们可以非常容易地
将数据嵌入一个父结构中。
<device>
<vendor>
Cisco ...
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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.