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This article mainly shows you "what is the use of XML Schema", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "what is the use of XML Schema" this article?

Like DTD (DTD Grammar Overview), XML Schema also constrains a class of XML documents and determines their structure, elements, attributes, and data types. And constraints on the elements, entities, attributes of elements, and the relationship between elements and entities used in XML documents. XML Schema was first proposed by Microsoft and has been accepted as a standard by the W3C. Unlike DTD, XML Schema files use XML syntax, which is designed for much the same purpose as DTD, but surpasses DTD in terms of functionality and extensibility. Here are some of the differences between them:

I. XML Schema is an XML document, unlike DTD, which has its own syntax. For developers, you don't need to know both syntax to write a well-formed XML document. For developing XML parsers, XML Schema is also a XML syntax, so it is more convenient to implement and support it. At the same time, XML Schema inherits the extensible advantages of XML.

two。 Define the data type. Data can only be declared as string type or string type child elements in a DTD file, such as PCDATA, CDATA, ID, and so on. In XML Schema, you can define data types as rich as programming languages, such as integer, floating-point, Boolean, date, and so on. This benefit is obvious, when you write a program to use an integer data, such as defined in DTD, you must convert it from a character to an integer, while XML Schema can be directly defined as an integer.

3. XML Schema is an open model. Such as the following XML document:

TG/DTLatte 1 2.00

Here is its DTD and Schema description:

DTD:

Schema

>

When the above XML document adds a 10:21 PDT element to:

TG/DT Latte12.0010:21 PDT

The above DTD will raise a validation error, while Schema will not.

four。 Integration of namespaces. A XML document can only be described by one DTD document, but can be described by multiple XML Schema documents. The latter fully supports namespaces.

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