XML is considered as the forerunner of how systems will be built in the future. Most of the limitations of HTML have been overcome with this language. For the long term maintenance and re-purposing of information, XML does the heavy lifting without computing gymnastics closer to the web publishing business, with greater improvements in information interchange. Given a choice, it is better to build new systems using XML, as the foundation to have more flexibility and also for the possibility of extending the system easily in the future.

XML is an important standard in the development of e-commerce systems that the people should know about it. It was initiated in December 1997 and is the result of a working group funded by the World Wide Web consortium known as W3C and various vendors. Due to the limits of HTML, XML was a result of frustration developed in the minds of HTML developers and users of complex web application. XML is now a standard that addresses many of these concerns.

Definition of XML

XML describes the format, presentation and provides application control over the content of the documents and systems using this language. It is much powerful than HTML. XML is likely to be the next generation language for the Web and business applications.

XML is a technology that lets developers create their own mark-up tags, so they are not limited to the tags available in HTML and to the functionality HTML allows. XML allows links that go to multiple locations. HTML allows for links that lead to one destination each.

XML is defined by a number of related specifications:

Extensible Mark-up Language (XML) 1.0 – Defines the syntax of XML. The XML specification is the primary focus.

XML Pointer Language (X pointer) and XML Linking Language (X link) – X link defines a standard way to represent links between resources. In addition to simple links, like HTML’s tag, XML has mechanism for links between read only resources. X pointer describes how to address a resource, X link describes how to associate two or more resources.

Extensible Style Language (XSL) – It defines the standard style sheet language for XML.

Why XML based Technology ?

1)    Reuse and re-purpose information quickly and efficiently.
2)    Reduce the maintenance costs associated with e-commerce solution
3)    Design flexibility into the system, making it easier when we want to make change as our business requirements dictate.
4)    Share information easily inside our organization and with our business partners.

Comparison of HTML with XML

Standard Generalized Mark-up language (SGML) provides a grammar for specifying document formats based on standard mark up annotations. HTML is a general-purpose hypertext display language, based on SGML. It specifies a document format that allows text formatting commands as well as hypertext-link commands and image display commands.

HTML provides limited input features. The HTML document can specify that a form should be displayed. The HTML display program (web client) allows the user to fill in entries in the form. Menus and other graphical input facilities are also provided. When the user has finished entering values, he can press a ‘submit’ button.

At that time, values entered by the user are collected, and the web client sends a request for the document, with the values entered by the user as arguments. This document is an executable program, and the web server invokes the program with the specified arguments. The actual lay out of the screen and the specific forms to be filled and the menu items to be chosen, are all under the control of HTML document. There is no continuous connection between the client and the server.

Structure of XML document

An XML document consists of two parts, the Document Type Definition (DTD) and the Document Body. The DTD defines the vocabulary and the structure of the document. It is the existence of the DTD that makes XML extensible. As long as two businesses or applications are using the same DTD, they will be able to understand each other. The body is simply a flat text document and is very convenient for electronic processing. For this reason, the W3C have defined the Document Object Model (DOM) as a high-level object representation of XML documents.

DOM is a set of interfaces that provide convenient object-based programmatic access to XML documents. The DOM API is defined in IDL. This allows an application or programmer to access and manipulate the structure and content of XML documents. A number of vendors including IBM, Sun and Microsoft provides parsers for their respective environments, which automatically transform between XML documents in their text format and an object representation that conforms to the DOM API.

Domain-specific applications can then manipulate XML documents in this convenient object form, without having to resort to manually encoding and decoding raw text files or proprietary vendor-specific APIs. There is also another API for electronically manipulating XML documents: SAX, the simple API XML is an event based API that allows documents to be easily parsed by the applications.

XHTML

XHTML is one other form of XML. It can be called as transition path from HTML to XML. XHTML by its very name is meant to be extensible. XHTML allows authors to retain the semantics present in HTML. Indeed, XHTML can be rendered in current HTML browsers with only a few minor considerations to backward compatibility. The electronic bridge from HTML to XML lets web developers sharpen their skills and becomes fully prepared for the explosion of XML about to occur on the Web.

Using XML, whatever document you prepare to store your useful data or secret data, needs to be protected. For this security purpose, we have one of the products in the market called X/Secure. It has been developed by Baltimor Technologies Pvt. Ltd.

X/Secure

X/Secure is a radically new product, which has provided XML digital signatures and XML encryption for the first time ever. X/Secure comprises of Toolkit for application developers and a suite of security utilities that can be used in system integrations. It provides full encryption and digital signature capabilities, which can be used in an intranet, extranet or Internet environment. X/Secure offers the following benefits:

-    Allows secure e-business XML systems to be created.
-    Provides complete confidentiality of XML documents.
-    Prevents tampering of documents during either transmission or storage.
-    Unique and irrefutable digital signatures can be applied to part or whole documents.
-    Full Public Key Infrastructure supports
-    No prior knowledge of cryptography is required.

Advantages of XML

1.    Its self-describing tags identify what your content is all about.
2.    Data is easily repurposed via tags.
3.    Creating, using and reusing tags is easy, making XML highly extensible.
4.    XML data types map easily among different applications, so it is very inter operable.
5.    It makes transferring data easy, simply give it XML tags.
6.    Without modifying the XML code, a company can provide access to the information stored in its mainframe server
7.    XML is easy to implement and offers numerous advantages to organizations, which would jump onto B2B E-commerce bandwagon by leveraging on their existing resources. The organizations will benefit from the flexibility and robustness provided by XML, thus making it lingua franca of B2B
8.    We can define new tags and attributes at will.
9.    Document structures can be nested to any level of complexity.
10.    Any XML document can contain an optional description of its grammar that needs to perform structure validation.

Disadvantages

1.    Majority of online browsers still see only HTML; you will need to add an XML to HTML translator.
2.    Performance is still lower than equivalent HTML documents.
3.    The XML tagged document is still rare; you will likely be doing a bit of conversion of older data.
4.    Standard tag sets for different applications ands industries are not in widespread use yet.

Application of XML

-    It can be used for database.
-    It is used to store the data and XSL; is used to display only those contents which we would like to display to the viewer.
-    It can be used as a web-developing tool, like HTML but has enhanced powers.
-    It is a machine independent language.