1. XML Processing SoftUni Team Database Applications Technical Trainers
Software University
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2. Table of Contents
What is XML?
LINQ to XML

3. What is XML?

4. XML – Example <?xml version="1.0"?>
<library name="Developer's Library">
<book>
<title>Professional C# 4.0 and .NET 4</title>
<author>Christian Nagel</author>
<isbn> </isbn>
</book>
<title>Teach Yourself XML in 10 Minutes</title>
<author>Andrew H. Watt</author>
<isbn> </isbn>
</library>

5. What is XML? XML (eXtensible Markup Language)
Universal notation (data format / language) for describing structured data using text with tags
The data is stored together with the meta-data about it
Used to describe other languages (formats) for data representation

6. What is XML? (2) XML looks like HTML
Text based language, uses tags and attributes
Industrial standard, supported by the W3C (
Independent of the hardware platform, OS and programming languages

7. XML – Example XML header tag (prolog) Attribute (key / value pair)
<?xml version="1.0"?>
<library name="Developer's Library">
<book>
<title>Professional C# 4.0 and .NET 4</title>
<author>Christian Nagel</author>
<isbn> </isbn>
</book>
<title>Teach Yourself XML in 10 Minutes</title>
<author>Andrew H. Watt</author>
<isbn> </isbn>
</library>
Root (document) element
Element
Opening tag
Closing tag
Element value

8. XML and HTML Similarities between XML and HTML
Both are text based notations
Both use tags and attributes
Differences between XML and HTML
HTML is a language, and XML is a syntax for describing other languages (meta-language)
HTML describes the formatting of information, XML describes structured information
XML requires the documents to be well-formed

9. Well-Formed XML Documents
Means "syntactically correct XML document"
All tags should be closed in the correct order of nesting
Attributes should always be closed
The document should contain only one root element
Tag and attribute names retain certain restrictions

10. Well-Formed XML Documents (2)
Example of incorrect XML document
Open / close tags do not match
Unclosed attribute values
Invalid characters, invalid spacing
Check for well-formed XML online:
<xml>
<button bug! value="OK name="b1">
<animation source="trailer.avi"> 1 < 2 < 3
</click-button>
< / xml >

11. XML: Benefits Benefits of XML:
XML is human readable (unlike binary formats)
Store any kind of structured data
Data comes with self-describing meta-data
Full Unicode support
Exchange data between different systems
Custom XML-based languages can be designed for certain apps
Parsers available for virtually all languages and platforms

12. When to Use XML? (2) Disadvantages of XML:
XML data is bigger (takes more space) than in binary formats
More memory consumption, more network traffic, more hard-disk space, more resources
Decreased performance
CPU consumption: need of parsing / constructing the XML tags
XML is not suitable for all kinds of data
E.g. graphics, images and video clips

13. LINQ to XML

14. LINQ to XML LINQ to XML LINQ to XML classes:
Use the power of LINQ to process XML data
Easily read, search, write, modify XML documents
LINQ to XML classes:
XDocument – represents a LINQ-enabled XML document (containing prolog, root element, …)

15. LINQ to XML Classes LINQ to XML classes:
XElement – represents an XML element in LINQ to XML
Methods: Parse(…), Save(), RemoveAtributes(…), SetElementValue(…), SetAtributeValue(…), WriteTo(…)
XAttribute
Name / value attribute pair

16. LINQ to XML – Searching with LINQ
Searching in XML with LINQ is like searching with LINQ in array
XDocument xmlDoc = XDocument.Load("../../books.xml");
var books =
from book in xmlDoc.Descendants("book")
where book.Element("title").Value.Contains("4.0")
select new {
Title = book.Element("title").Value,
Author = book.Element("author").Value };
foreach (var book in books) {
Console.WriteLine(book); }

17. Creating XML with XElement
Need to create this XML fragment?
<books>
<book>
<author>Don Box</author>
<title>Essential .NET</title>
</book>
XElement books =
new XElement("books",
new XElement("book",
new XElement("author", "Don Box"),
new XElement("title", "ASP.NET") ) );

18. Additional XML classes to consider:
XML Document – old version of Xdocument
 XmlReader/XmlWriter - huge XML which cannot fit into memory

19. XML Processing https://softuni.bg/courses/
© Software University Foundation –
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike license.

20. License
This course (slides, examples, demos, videos, homework, etc.) is licensed under the "Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International" license
Attribution: this work may contain portions from
"Databases" course by Telerik Academy under CC-BY-NC-SA license
© Software University Foundation –
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike license.

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