XML (eXtensible Markup Language)
XML is a flexible, tag-based markup language used for encoding structured data in a format that is both human-readable and machine-readable. It is widely used for data exchange, document representation, and system configuration.
XML stands for eXtensible Markup Language. It was the dominant format for structured data interchange before JSON became popular, and it's still heavily used in enterprise systems. XML uses a nested tag structure to represent data, where each element is enclosed in a start and end tag, often with attributes for metadata.
Unlike HTML, which has a predefined set of tags, XML allows developers to define their own tags and structure, making it ideal for representing custom or domain-specific data. XML is also commonly used with schemas such as XSD (XML Schema Definition) to enforce validation rules.
Example of XML
<product>
<id>1</id>
<name>Apple</name>
<price currency="USD">0.5</price>
</product>JSON vs. XML
- Verbosity: XML is more verbose due to its use of both opening and closing tags. JSON uses key-value pairs, making it more compact and readable.
- Data Types: JSON natively supports
string,number,boolean,null,object, andarray. XML treats all data as strings unless schema constraints are applied. - Parsing: JSON maps directly to data structures in most programming languages (e.g., dictionaries, objects), making it easier and faster to parse. XML requires DOM or SAX parsers, which can be more complex and slower.
- Metadata Support: XML supports attributes on elements, which can store additional metadata. JSON lacks a built-in equivalent, though metadata is often embedded in nested keys.
- Schema Validation: XML has robust schema support (XSD, DTD). JSON also supports schemas (like JSON Schema), but adoption is more recent.
While JSON has become the go-to for modern APIs and frontend-backend communication, XML is still widely used in:
- SOAP-based web services
- Java-based enterprise applications
- Android app layout and resource files
- Microsoft Office document formats (e.g., DOCX, XLSX)
- Configuration files like
pom.xml,web.config, or.plist
You can use a JSON to XML Converter to transform structured data between these formats for compatibility with legacy systems or integrations.