XML Interview Questions and Answers
This section covers frequently asked XML interview questions.
1. What is XML?
XML (Extensible Markup Language) is a markup language for encoding documents in a format that is both human-readable and machine-readable. It's used for data storage and exchange.
2. XML vs. HTML.
| Feature | HTML | XML |
|---|---|---|
| Purpose | Display data | Store and transport data |
| Case Sensitivity | Not case-sensitive | Case-sensitive |
| Structure | Predefined tags | Customizable tags |
3. Version in XML.
The XML declaration (like ``) specifies the XML version and encoding.
4. Benefits of XML.
- Simplicity and readability.
- Open standard.
- Extensibility (create custom tags).
- Self-describing (metadata embedded in tags).
- Scalability.
- Platform independence.
5. XML DOM (Document Object Model).
The DOM is a programming interface for accessing and manipulating XML documents. It represents the document as a tree-like structure.
6. SAX (Simple API for XML).
SAX is an event-driven parser; it processes XML sequentially, providing notifications for events (like starting and ending elements).
7. XSNML (XML Search Neutral Markup Language).
XSNML is a query language for searching XML documents. It is an intermediary between the search interface and the data source.
8. Well-Formed XML Documents.
A well-formed XML document follows basic XML syntax rules (proper nesting, closed tags, etc.).
9. Valid XML Documents.
A valid XML document is well-formed and conforms to a defined schema (DTD or XSD).
10. DTD (Document Type Definition).
A DTD defines the structure of an XML document (elements, attributes, etc.).
11. Applying a DTD to an XML Document.
You can either embed the DTD within the XML document or reference it as an external file.
12. Rules for Writing XML Documents.
- Single root element
- Closed tags
- Proper nesting
- Case sensitivity
- Attribute values in quotes
13. XSL (Extensible Stylesheet Language).
XSL is used for defining stylesheets to control how XML documents are displayed.
14. XPath.
XPath is a query language used to navigate and select nodes within an XML document.
15. XSLT (Extensible Stylesheet Language Transformations).
XSLT transforms XML documents into other formats (like HTML).
16. XML DTD vs. XSD (XML Schema Definition).
| Schema Type | Features |
|---|---|
| DTD | Simpler, no namespace support |
| XSD | More powerful, supports namespaces, data types |
17. XML and HTML.
XML is for data; HTML is for display.
18. Elements and Attributes.
An element is a section of XML enclosed in tags. An attribute provides additional information about an element.
19. Simple vs. Complex Elements.
A simple element contains only text; a complex element can contain other elements and attributes.
20. XPointer.
XPointer specifies a fragment within an XML document.
21. XML Data Binding.
XML data binding converts XML data into program objects, simplifying data access and manipulation.
22. XML Encoding Errors.
(This section details potential XML encoding errors and how to avoid them, typically by specifying an encoding like UTF-8.)
23. XML APIs.
- Tree-based APIs (like DOM): Load the entire XML document into memory as a tree structure.
- Event-based APIs (like SAX): Process XML sequentially, handling events.
24. XmlReader Class.
(This section would describe the `XmlReader` class, a non-cached, forward-only reader for XML data in .NET.)
25. CDATA vs. PCDATA.
CDATA (Character Data) is treated as text; PCDATA (Parsed Character Data) is parsed for markup.
26. XQuery.
XQuery is a query language for XML data.
27. XML Namespaces.
Namespaces prevent element name conflicts in XML documents.
28. SGML (Standard Generalized Markup Language).
SGML is a meta-markup language; XML is a subset of SGML.
29. Graphics in XML.
XML can reference images using XLink and XPointer.
30. XML Case Sensitivity.
XML is case-sensitive.
31. Structure of XML.
(This section would detail the structure of an XML document, including the root element, elements, attributes, and proper nesting.)