Abstract XML is useful as a generic data format when you want your data to be directly readable by both computers and users. XML's syntax makes data interchange easier when using known XML document types, but XML does not convey the meaning behind the data it represents, so its utility as a universal format, while better than what was previously available, is limited. These types of web technologies and web servers, offers new opportunities for the construction of grid infrastructures that are flexible and extensible. Traditional data models cannot fully support and handle the new arriving problems in transactions and especially e-business over web and desktop level, so XML taking over traditional system into it, which is used for such kind of data models, like object exchange model (OEM). Different kind of advantages and disadvantages XML has, during its work with those semi-structured technologies and different other languages, which are actually powerful languages also derived, form it. It's a revolution in web base technologies. World Wide Web Consortium (W3c) makes XML easy for the complex programs for web, its actually application and vendorindependent and easy to use. This paper will first describe the impact of XML on data management for both well structured and more loosely structured data. Thelongest section outlines the introduction that XML does and does not address, further more about data interoperability, data integration, grids and in the end conclusion of report that tell the whole story of this paper and you may can say the outcomes of this paper.
1.0 Introduction The abbreviation XML stands for eXtensible (Extended) Markup Language. It is markup language much like HTML. It was design to describe data. Its tags are not predefined you have to define your own tags. It provides a foundation for creating documents and it is XML that transfer documents into some thing new. By using XML, you can define the tags for your markup language. XML facilitate with method or scheme that help in storing the data or information in well structured way. XML specification defines an XML documents as data object that confirm to the rules of well- formed document. A well formed document must meet some standards to be considered as a well formed. A well formed document is not valid until it meets the constraints define by Standard Generalized Markup Language (SGML). XML is derived from SGML; it is modified version of SGML, especially for the designed of Web documents. Even it is called as the subset of SGML. XML documents usually consist of two main parts The prolog Version control and Document Type Definition (DTD) The body Contain the rest of markupDTD contain the markup deceleration that that provide a grammar for a class of documents. This grammar is known as DTD. This declaration can be element type declaration, an attribute list declaration, an entity type declaration, or a notation declaration. There are two main level of XML, first it provides syntax for documents and second it provides syntax for declaring the structures of documents. Data is integrated in XML documents as strings of text, and data is bordered by text markup that explains the data [Dan Suciu 2001]. One particular unit of data and markup is called an element. XML document is made up of one or more elements. Originally designed to meet the challenges of large-scale electronic publishing, but it also provide and increasingly very important role in the exchange of a wide variety of data on the web and elsewhere [Kuchling A, 1998]. Success of XML is based upon three powerful concepts, one of them is to reusability of data in different ways secondly it provides building blocks which can be use to design new languages and finally third is to use way of encoding electronic documents in a standardized format. [Stephan Taylor 2003]. The tool of XML allows developers to create web pages and much more. It is XML that give developer a luxury to set the standards and define the information that should appear in a document, and also in what sequence. Developers and users can work with XML directly without need of any special software. XML provides very friendly environment to both programmers and the person who write the documents. It has very fix rule for documentation that help in reading documents more easily. XML is commonly agreed-upon format for data exchanged between systems and suited to delivery and interoperability over the Web. One of the big issue for any big or small organization either it is bank or a recruitment company or a showroom or even a small company is the safety of their precious data and their valuable internal information. Using different tools for different parts of the document and allowing different users to access the data raise the security issue in system, which could cause serious problem sometimes. This particular issue is solved efficiently in XML, by limiting the access of different user up to different levels. Every level of users has different level of access to same date with compare to the other levels. There are many problems in XML with the databases. Internet applications and the new ways in which they handle data are changing the role of database theory and its relationship with practice. Three particular problems XML have with work with databases, XML publishing, XML type checking and XML storage. XML publishing problem is a normalization problem, like relational database is normalized and at the other side XML schema is also formed into tree form, so it may conflict with the internal organizational rules. XML type checking is another problem with XML, because XML schema or DTD involve in type checking dynamically and error chances can be high by run time. XML storage is a problem because the data is labeled tree in XML format and in relational databases the data is in the tables so the problem of storing data in one or several tables is a challenge and it causes problems some times. XML defines structure based on the information being given. This allows authors to define the rules separately for displaying the XML data using Style Sheets [Iraklis Varlamis 2001]. XML give following advantages to its users with many more:1.1
1.1 Advantages of XML Here are some good points of XML, which had made XML so popular. Simplicity Extensibility Flexibility Separation of Data and Display Openness Reusability of Data Data Security