XML or eXtensible Markup Language, is a markup language used for storing and exchanging information. It has been developed as an open standard that defines the syntax of documents in an unambiguous way. It also allows you to add your tags to the standard ones. In this article, we will explain what XML is and how it works with other languages
XML File Structure
XML files are structured in the same way as HTML files.
They contain elements and attributes, which can be nested to any level. An XML
document may contain one or more root elements (or root tags), then other tags
that contain the information you want to describe your data.
XML Syntax rules
XML syntax rules are similar to HTML syntax rules, but
there are some differences. In XML, you must use proper capitalization and
punctuation marks when writing your document.
XML elements
XML elements are the building blocks of an XML document. They can be defined by start tags, end tags and content.
XML Comments
XML comments are a way of adding documentation to your
XML document. They can be added anywhere in the document and don't have to
appear at the beginning or end, but they are always ignored by XML processors.
They aren't part of the XML document itself; they won't be visible when you
open up an editor for editing your file in Notepad++ or any other text editor
that supports nested elements.
XML Attribute
XML attributes are used to add extra information to an
element. They can be used to describe the element, and they are not
case-sensitive.
XML attributes follow the style of a tag's name: if you
are looking at tags in your source code, you will see that they have an
attribute called src="http://www.example1.com/images/logo1.jpg" where
"http://www." is replaced by whatever domain your site uses.
A single attribute will always go after any other
elements within its parent tag; if you have multiple nested tags or elements
within one parent tag, then each child will also have its own set of attributes
added on top of that original one set for all its siblings down through their
parents' children until reaching root level where no more attributes exist
anymore -- though there might still be some leftover ones from previous levels!
XML Namespace
You can use the xmlns attribute to define a unique name
for an element that can be used in the XML file. The namespace is introduced
using this attribute, which must be placed at the beginning of an element's
declaration.
The XML namespace specification defines how an XML
document should look when it is processed by another application, e.g., a
browser or editor.
It is used to specify what elements and attributes are
allowed within a particular document, as well as whether they may appear in
other documents i.e., derived documents. The namespace system defines this relationship
between namespaces and their corresponding elements; it also defines rules for
choosing one set over another when two different namespaces contain overlapping
entries or definitions.
The root element is always declared first: its content
defines all following declarations for its descendants' type attributes and
contents respectively; if there are no children then this declaration becomes
empty too!
XML CDATA section
The CDATA section is used to escape characters that might
otherwise be misinterpreted as markup. For example, if you want to represent a
URL in XML with characters such as. and /, then use CDATA sections:
Hello]>]]>
Why use XML?
XML is used for data storage and transfer, data exchange
and document formats. XML is also used to build web services that can be
accessed by other applications through HTTP requests.
Advantages of XML
1. Extensibility
2. Validity
3. Readability
4. Flexibility
Conclusion
XML is a markup language
for document structure and semantic annotations. XML provides its users better
control over their documents, compared to the traditional way of just using
HTML. Using XML, the user can describe not only what the document looks like structurally
in terms of headings, paragraphs etc., but also they can add related
information that allows easy navigation and indexing out of such structured
data.
