xmln:tns 和 targetNamespace [英] xmln:tns and targetNamespace
问题描述
我看到一些 XSD 架构文档在其顶部 schema
元素中声明了 targetNamespace
和 xmlns:tns
属性.例如.以下是从这里.它们似乎也具有相同的字符串值.我了解 targetNamespace
的作用,但是 xmlns:tns
在此基础上还能做什么?
I am seeing some XSD schema documents that declare both a targetNamespace
and an xmlns:tns
attribute in their top schema
element. E.g. the following one taken from here. They also seem to have the same string value. I understand the role of targetNamespace
but what does xmlns:tns
do on top of that?
<?xml version="1.0" encoding="UTF-8"?>
<schema
xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/Product"
xmlns:tns="http://www.example.org/Product"
elementFormDefault="qualified">
...
推荐答案
它允许您稍后在架构中引用命名空间.例如,如果您声明了一个命名类型,然后还想声明该类型的元素
It lets you refer to the namespace later in the schema. For example, if you declare a named type and then want to also declare an element of that type
<complexType name="someType">
<!-- ... -->
</complexType>
<element name="someElement" type="tns:someType" />
简单地说 type="someType"
是行不通的,因为那将指的是 http://中的(不存在的)
命名空间(架构文件的 someType
www.w3.org/2001/XMLSchemaxmlns="..."
)而不是 http://www 中的命名空间.example.org/Product
命名空间.
Simply saying type="someType"
wouldn't work because that would be referring to the (non-existent) someType
in the http://www.w3.org/2001/XMLSchema
namespace (the xmlns="..."
of the schema file) rather than the one in the http://www.example.org/Product
namespace.
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