XML

XML stands for eXtensible Markup Language, widely used for data transfer and application configuration. XML looks similar to the HTML but the tags and elements are not predefined.

Key Features:

1. Universal Standard XML is not tied to any specific platform, programming language, or application, making it a universal standard for data interchange.
2. Self-descriptive XML is self-descriptive, the data is represented using self-defined tags which represent the attribute of the data.
3. Hierarchical Structure XML follows a hierarchical structure, organized in a tree-like format. Elements can have parent-child relationships, allowing the representation of complex data structures.
4. Tags and Elements Data in XML is enclosed within tags, which define elements. Elements can have attributes and contain text, other elements, or a combination of both.
5. language-neutral XML is platform-independent and language-neutral. It can be used across different programming languages and operating systems, making it suitable for diverse applications and environments.

<aside> 💡 An XML can be written and read with the help of certain libraries such as JAXB, DOM and SAX.

JAXB - stands for Java Architecture for XML binding DOM - stands for Document Object Model SAX - stands for Simple API for XML

Note:

• JAXB: Part of Java SE 6-8, but excluded for Java SE 9+.
• DOM and SAX: Included in all versions of Java SE. </aside>

But A Simple XML file can be used only for the internal project configuration and data transfer between the two client and server application who know how to read the file.

But cannot be used in case:

• If the configuration is related to an external library added to the project, reason: the external library cannot understand what the developer has written, as the developer is allowed to write any tags he want, the external library cannot pre assume how it has to be read.
• If the data-transfer is happening between two applications, which are not under the same community or the company. reason: consider Project A and Project B , both developed by different companies. If in case project B has to send some data to the project A through XML file, the project A should know how to read that XML file, but apparently both projects are developed by different project team and companies, so it is not possible to communicate.

But this issue can be solved by using XSD.

XSD

XSD stands for XML Schema Definition. The XSD provides a way to validate the XML, clearly defining the expected structure and data types. This reduces the chances of miscommunication or misunderstandings.

An XML with XSD can only contain those tags that are defined in the XSD. This helps in applying universal laws on which the XML has to be written and read which are common to all applications.

E.g.,