What is XML? #
XML stands for eXtensible Markup Language. It is a markup language that defines a set of rules for encoding files in a format that is both human-readable and machine-readable. XML is widely used for storing and transferring data across different systems and platforms.
XML uses tags to define elements within a file, similar to HTML. However, unlike HTML, which is primarily used for defining the structure of web pages, XML is a general-purpose language that can be used to represent any kind of structured data.
What is XML used for? #
XML provides a flexible and self-describing format for representing structured data. It is widely used in various domains, including web services, configuration files, data storage and interchange formats between different systems. XML files can be parsed and processed by software applications using XML parsers and libraries in various programming languages.
XML enables standardisation by providing a flexible and extensible markup language that can represent various types of structured data. It promotes interoperability between different systems and applications by defining a common syntax and structure for data representation.
For example, XML is widely used for data integration and transformation tasks between different systems, applications and platforms. It provides a standardised format for representing and exchanging structured data, making it easier to share and integrate information between different sources. It is often used in electronic data interchange (EDI) systems to facilitate the exchange of business documents and transactions between organisations.
Similarly, XML also plays a significant role in web services, allowing different applications to communicate and interact with each other over the internet. It is used for describing the structure and content of messages exchanged between web services, enabling interoperability between diverse systems.
XML can also be used as a data format for storage and retrieval purposes, particularly in scenarios where hierarchical or semi-structured data needs to be persisted. XML databases and XML-based data storage solutions offer efficient methods for storing and querying XML data.
Therefore, it is often used in content management (CMS) and document management systems as it allows for the creation of custom document schemas, facilitating the management of document metadata, version control and document workflow processes, as well as the separation of content from presentation, enabling content reuse, multi-channel publishing and dynamic content generation.
These are just a few examples of how XML is applied in business contexts. XML’s versatility and compatibility with other technologies make it a popular choice for various data-centric and document-centric applications in the business world.
What is an XML file? #
An XML file is a structured text file that follows the rules and syntax defined by the XML specification. XML is a markup language that is designed to store and transport data in a self-descriptive and platform-independent manner. It is widely used for representing and exchanging structured data between different systems, applications and platforms.
An XML file consists of a series of markup tags that define the structure and content of the data. These tags are enclosed in angle brackets (“<" and ">“) and form hierarchical elements. Each element can contain text, attributes and child elements, allowing for the representation of complex data structures.
What are predefined XML entities? #
XML also uses entities in XML files to represent special characters or symbols that have a predefined meaning. They provide a way to include reserved characters in XML content without conflicting with the markup syntax.
There are five predefined XML entities that can be used in XML files:
If you want to include these characters as literal data within XML content, using their raw form may lead to syntax errors or misinterpretation by XML parsers. By using XML entities, you can represent these characters without conflicting with the XML syntax.
For example, if you want to include an ampersand symbol (&) in your XML content, using & as an entity reference ensures that the ampersand is treated as data rather than the start of an entity reference.
XML entities can be used to represent characters that are not part of the character set supported by the chosen encoding. For instance, if you’re using an encoding that doesn’t support a specific character, you can define a custom entity for it and reference it in your XML document.
XML entities can be defined once and then referenced multiple times within an XML file, meaning you can use the same entity reference wherever the corresponding character or symbol is needed, instead of repeating the actual character sequence.
XML entities can also make XML documents more human-readable and self-explanatory. Instead of deciphering the meaning of raw special characters, using entity references makes it easier to understand the intended content.
XML entities essentially help ensure proper parsing, handle special characters, support different encodings, enhance readability and provide a mechanism for reusing character sequences in XML files.
The benefits of XML #
XML’s flexibility, portability and support for structured data make it a widely adopted format for data representation, exchange and integration across different systems and platforms.
- Structured data: XML allows data to be structured hierarchically, making it easier to organise and represent complex information.
- Platform independence: XML is platform-independent, meaning it can be used on any operating system or device with an XML parser.
- Interoperability: XML facilitates data exchange between different systems and applications, as it provides a standardised format that can be understood by various software.
- Extensibility: XML is highly extensible, allowing for the creation of custom tags and attributes to suit specific data requirements.
- Human readability: XML is designed to be human-readable, making it easier for developers and users to understand and work with XML files.
- Data validation: XML supports the use of Document Type Definitions (DTDs) and XML Schema to define the structure and constraints of data, enabling data validation and integrity checks.
- Integration: XML can be seamlessly integrated with other technologies, such as web services, to enable communication and data exchange between different systems.
- Data transformation: XML can be transformed into other formats using technologies like XSLT, allowing for data conversion and presentation in various ways.
- Versioning and document updates: XML enables versioning and updates to documents by maintaining backward compatibility and supporting incremental changes to data structures.
- Metadata support: XML provides a flexible framework for adding metadata to documents, allowing for additional information and context to be associated with the data.