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---
language: xml
filename: learnxml-ru.xml
contributors:
- ["João Farias", "https://github.com/JoaoGFarias"]
translators:
- ["Dmitry Bessonov", "https://github.com/TheDmitry"]
lang: ru-ru
---
XML - это язык разметки, предназначеный для хранения и передачи данных.
В отличие от HTML, XML не определяет, как отображать или формировать данные, он только содержит их.
* XML Синтаксис
```xml
<!-- Комментраии в XML выглядят так -->
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book category="КУЛИНАРИЯ">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="ДЕТИ">
<title lang="ru">Гарри Поттер</title>
<author>Дж. К. Роулинг</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="ВСЕМИРНАЯ ПАУТИНА">
<title lang="ru">Изучаем XML</title>
<author>Эрик Рэй</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>
<!-- Вышеописанный документ - типичный XML-файл.
Он начинается с определения, информирующее о некоторых метаданных (необязательно).
XML использует древовидную структуру. У вишеописанного документа корневой узел - 'bookstore', который содержит
три дочерних узла - все 'books'. Такие узлы содержат много дочерних узлов и т.д.
Узлы создаются с помощью открывающего/закрывающего тегов, а дочерние - это узлы между
открывающимися и закрывающимися тегами.-->
<!-- XML carries two kind of data:
1 - Attributes -> That's metadata about a node.
Usually, the XML parser uses this information to store the data properly.
It is characterized by appearing in parenthesis within the opening tag
2 - Elements -> That's pure data.
That's what the parser will retrieve from the XML file.
Elements appear between the open and close tags, without parenthesis. -->
<!-- Below, an element with two attributes -->
<file type="gif" id="4293">computer.gif</file>
```
* Well-Formated Document x Validation
A XML document is well-formated if it is syntactically correct.
However, it is possible to inject more constraints in the document,
using document definitions, such as DTD and XML Schema.
A XML document which follows a document definition is called valid,
regarding that document.
With this tool, you can check the XML data outside the application logic.
```xml
<!-- Below, you can see an simplified version of bookstore document,
with the addition of DTD definition.-->
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE note SYSTEM "Bookstore.dtd">
<bookstore>
<book category="COOKING">
<title >Everyday Italian</title>
<price>30.00</price>
</book>
</bookstore>
<!-- This DTD could be something like:-->
<!DOCTYPE note
[
<!ELEMENT bookstore (book+)>
<!ELEMENT book (title,price)>
<!ATTLIST book category CDATA "Literature">
<!ELEMENT title (#PCDATA)>
<!ELEMENT price (#PCDATA)>
]>
<!-- The DTD starts with a declaration.
Following, the root node is declared, requiring 1 or more child nodes 'book'.
Each 'book' should contain exactly one 'title' and 'price' and an attribute
called 'category', with "Literature" as its default value.
The 'title' and 'price' nodes contain a parsed character data.-->
<!-- The DTD could be declared inside the XML file itself.-->
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE note
[
<!ELEMENT bookstore (book+)>
<!ELEMENT book (title,price)>
<!ATTLIST book category CDATA "Literature">
<!ELEMENT title (#PCDATA)>
<!ELEMENT price (#PCDATA)>
]>
<bookstore>
<book category="COOKING">
<title >Everyday Italian</title>
<price>30.00</price>
</book>
</bookstore>
```
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