What is xml?

What is xml?

XML, or Extensible Markup Language, was file format designed to make information sharing and data interpretation easier on the World Wide Web, intranets, and elsewhere using standard ASCII text. Before you start to learn xml, you should know basic of HTML & JavaScript.

The Difference Between XML and HTML

XML and HTML were designed with different goals:

• XML was designed to carry data - with focus on what data is
• HTML was designed to display data - with focus on how data looks
• XML tags are not predefined like HTML tags are

XML is similar to HTML. Both XML and HTML contain markup symbols to describe the contents of a page or file. HTML, however, describes the content of a Web page (mainly text and graphic images) only in terms of how it is to be displayed and interacted with.

XML describes the content in terms of what data is being described. An XML file can be processed purely as data by a program or it can be stored with similar data on another computer or it can be displayed, like an HTML file.

What is mark-up language?

A mark up language is a modern system for highlight or underline a document. 

Students often underline or highlight a passage to revise easily, same in the sense of modern mark up language highlighting or underlining is replaced by tags.

The essence of XML 

It is in its name: Extensible Markup Language.

The XML is quite self-descriptive:

• It has sender information.
• It has receiver information
• It has a heading
• It has a message body.

Extensible

XML is extensible, unlike HTML, the markup symbols are unlimited and self-defining. It lets you define your own tags, the order in which they occur, and how they should be processed or displayed. Another way to think about extensibility is to consider that XML allows all of us to extend our notion of what a document is: it can be a file that lives on a file server, or it can be a transient piece of data that flows between two computer systems (as in the case of Web Services).

Markup

The most recognizable feature of XML is its tags, or elements (to be more accurate). In fact, the elements you’ll create in XML will be very similar to the elements you’ve already been creating in your HTML documents. However, XML allows you to define your own set of tags.

Language

XML is a language that’s very similar to HTML. It’s much more flexible than HTML because it allows you to create your own custom tags. However, it’s important to realize that XML is not just a language. XML is a meta-language: a language that allows us to create or define other languages. For example, with XML we can create other languages, such as RSS, MathML (a mathematical markup language), and even tools like XSLT. 

Why Do We Need XML?

XML is  a Platform Independent and Language Independent: We need it because HTML is specifically designed to describe documents for display in a Web browser, and not much else. It becomes cumbersome if you want to display documents in a mobile device or do anything that’s even slightly complicated, such as translating the content from German to English. HTML’s sole purpose is to allow anyone to quickly create Web documents that can be shared with other people. XML, on the other hand, isn’t just suited to the Web – it can be used in a variety of different contexts, some of which may not have anything to do with humans interacting with content (for example, Web Services use XML to send requests and responses back and forth).

HTML rarely (if ever) provides information about how the document is structured or what it means. In layman’s terms, HTML is a presentation language, whereas XML is a data-description language.

The main benefit of xml is that you can use it to take data from a program like Microsoft SQL, convert it into XML then share that XML with other programs and platforms. You can communicate between two platforms which are generally very difficult.

The main thing which makes XML truly powerful is its international acceptance. Many corporation use XML interfaces for databases, programming, office application mobile phones and more. It is due to its platform independent feature.

XML Simplifies Things

• It simplifies data sharing
• It simplifies data transport
• It simplifies platform changes
• It simplifies data availability

The XML standard is a flexible way to create information formats and electronically share structured data via the public Internet, as well as via corporate networks.

XML data is known as self-describing or self-defining, meaning that the structure of the data is embedded with the data, thus when the data arrives there is no need to pre-build the structure to store the data; it is dynamically understood within the XML. The XML format can be used by any individual or group of individuals or companies that want to share information in a consistent way. XML is actually a simpler and easier-to-use subset of the Standard Generalized Markup Language (SGML), which is the standard to create a document structure.

The basic building block of an XML document is an element, defined by tags. An element has a beginning and an ending tag. All elements in an XML document are contained in an outermost element known as the root element. XML can also support nested elements, or elements within elements. This ability allows XML to support hierarchical structures. Element names describe the content of the element, and the structure describes the relationship between the elements.

An XML document is considered to be "well formed" (that is, able to be read and understood by an XML parser) if its format complies with the XML specification, if it is properly marked up, and if elements are properly nested. XML also supports the ability to define attributes for elements and describe characteristics of the elements in the beginning tag of an element.

For example, XML documents can be very simple, such as the following:

<?xml version="1.0" standalone="yes"?>

<conversation>

<greeting>Hello, world!</greeting>

<response>Stop the planet, I want to get off!</response>

</conversation>

Applications for XML are endless. For example, computer makers might agree upon a standard or common way to describe the information about a computer product (processor speed, memory size, and so forth) and then describe the product information format with XML code. Such a standard way of describing data would enable a user to send an intelligent agent (a program) to each computer maker's Web site, gather data, and then make a valid comparison.

XML's benefits sometimes appeared revolutionary in scope shortly after it was introduced. However, as a concept, it fell short of being revolutionary. It also fell short of being the panacea. The over-application of XML in so many areas of technology diminished its real value, and results in a great deal of unnecessary confusion. Perhaps most damaging is the predictable behavior of many vendors that look to recast XML using their own set of proprietary extensions. Although some want to add value to XML, others seek only to lock in users to their products.

XML's power resides in its simplicity. It can take large chunks of information and consolidate them into an XML document ‑ meaningful pieces that provide structure and organization to the information.