XML (Extensible Markup Language): Definition and Structure

People who are not into web development and programming very often misunderstand and confuse XML and HTML definitions. In order to explain the difference between these two terms – let’s appeal to a definition and structural elements of XML language.

Extensible Markup LanguageXML Definition

XML is a shortening for Extensible Markup Language. However, it is wrong to suppose XML stands only for this definition and exists only as a markup language because at the same time XML should be also understood as a metalanguage as well. As a markup language XML shows the specific path for data containing in an electronic  document which has to be used by another application, XML denotes a document’s structure and content for another computer program to identify them. It marks up the content via a title and certain tags/symbols. The same role plays another popular markup language HTML and that is why many people find them very similar if not identical ones.

XML serves as a method letting in a flexible way develop and then share data in general information formats in order to transfer them to the Internet, intranets, etc. XML can be applied within a group for sharing certain data online or by individuals who want to encrypt transferred information.

By means of all metalanguages including XML it is possible to perform calculations and actions in certain programs like C++ or Java. A metalanguage allows creating new languages (based on XML) which in their turn let creation of new documents and files. Many modern applications and programs are based on XML – Java Servlets, SharePoint, MathML and RSS programming XHTML, etc.

XML Structure

As a markup language XML applies the following major tags <zone> and </zone> to mark up data of a document. Such data marked up with this tags is called an element. If there are used name-value pairs of tags to give a definition of an element they are called as attributes. For instance, zone= “postal code” shows what an element has been defined in the XML based data as a postal code to emphasize it.

Along with XML elements and attributes is used the so-called a document type definition (shortly DTD) which shows XML data in a document separated by paragraphs and headings. A XML DTD reader app receives a message with any sort of XML based data and processes this data to display properly the information it encrypts. XML is applied only to transport data in one of text formats. If a user intends to display the data to an interface he should convert XML based information into a different format, for instance, scalable vector graphics.

XML and HTML: Similar or Different?

Being both markup languages containing markup symbols and used in similar web applications XML and HTML differ from one another significantly. XML is applied to transfer and store data in a text format, focusing on data’s content. And HTML was developed to display document’s data focusing on the way this data looks. XML based documents carry information, while HTML documents display this information.

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XML Language Development and Benefits

XML Language Development Appealing to the history, XML (a shortening of Extensible Markup Language) was approved in an official way by the W3C (World Wide Web Consortium) in mid 1998. The development of this markup language and simultaneously metalanguage was dictated by the needs of web developers who were not satisfied with certain aspects of the earlier universal markup language – HTML.

XML History and Development

Being similar to HTML, XML stands for a Standard Generalized Markup Language’s subset and was developed with a mission to address all the limitations existed in HTML and SGML languages. SGML’s lack was complicated to apply in the World Wide Web because it wasn’t supported by the Internet browser applications. HTML was also created as a simpler derivative from complicated SGML but such simplicity also provided certain limitations in presentation’s terms since HTML uses a limited set of tags. To fix this problem was created Cascading Style Sheets (CSS) but still the capabilities of these two powerful markup languages were quite limited.

Discussions about the necessity of XML creation appeared in 1996 and back to those days were made dew attempts to develop a totally new markup language with versatile capabilities similar to SGML  as well as simple in usage just like the elements of HTML.

To pioneers and the first creators of XML belong Jon Bosak and Tim Bray who used their theoretical and practical knowledge in SGML to develop a brand new markup language free from complexities of SGML showing its high potential to define a certain document in detailed structure and identification through the tags and Document Type Definitions.

Via XML it also became possible to transmute HTML into an authentic XML application making in such way the next-gen XHTML app.

XML Benefits

XML language’s creation brought to web development a lot of abilities, among which the most important is definition all types of data in a universal text format which can be processed via any platform. Such ability opened a range of capabilities for building business applications because this new markup language has not to be connected with a certain solution provider.

To the most significant benefits of XML belong:

1) XML stands for a standard which can’t be changed by third-party solution providers which could make it incompatible with next-gen platforms or systems.

2) High interoperability classifies XML applied in business applications which let owners of these apps merge different apps’ information to get more efficient results.

3) Such interoperability of XML gives a chance to succeed in usage of business-to-business E-commerce apps because XML is capable to define standard-based messages while exchanging data via the orders.

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