FLEXIS – A FleXible Information System based on XML Data Model Abstract
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FLEXIS – A FleXible Information System based on XML Data Model
Varun Chandola, Subhash Chand, Srivatsava R Ganta, Aravind Krishna, Sundeep Narravula, Sreenivasa K Puligundla
Department Of Computer Science & Engineering, IIT Madras, Chennai
Abstract Semi-structured data has gained a lot of prominence in the recent past, especially after the realization of the inadequacy of HTML for information representation on the WEB. Semi-structured data is characterized by lack of rigid structure (schema) and evolving structure. XML has been adopted as a practical model for representing semi-structured data and also as the standard for data exchange on the WEB. Availability of a flexible data model naturally leads to flexible information systems. This paper describes an attempt in designing and implementing an information system, called FLEXIS, built around the XML data model with the aim of demonstrating the features of flexibility and extensibility. The system has information contributors, viewers and an administrator. Administrator (ADM) contributes Document Type Definitions (DTD’s) representing the templates that can be used by the information contributors. The system dynamically generates HTML editors from the DTD’s which can be modified by the ADM at anytime. Structural summary of the information present in the system is also dynamically generated to enable viewers to pose sophisticated queries on the system. A novel visual and interactive query building capability makes the system usable by novice end-users without the knowledge of XML query languages. The generic FLEXIS system can be used for a variety of applications involving gathering, storage and retrieval of semi-structured data. We describe how FLEXIS is used to build a prototype Campus News Site (CNS) for use within the campus of the Indian Institute of Technology Madras.
1. Introduction Knowledge management has lately become a very important concept with respect to the Internet. With unmanageable amount of information available it becomes very important to manage relevant data in such a way that it can be utilized in an efficient manner. Recently a lot of work has been gone into developing systems to collect and store data and provide mechanisms to search for a particular data item. The principal characteristic of this data is that it comes from heterogeneous sources and lacks any substantial structure. This not only makes the accumulation of information difficult but also imposes restraints on its storage and retrieval. With its semi-structured nature and its popularity as a standard for data exchange on the Internet, XML [1] can be employed effectively to manage this information. The FLEXIS System is aimed at providing a means for gathering, storing and retrieval of information. The system handles the data without compromising on the nature of the data – by not constraining it within a format/schema. The system is designed to handle data that has evolving or missing schema (i.e.) semi-structured data. XML has been chosen as the model to represent semi-structured data due to its scalability and simplicity. The system is built with an environment where there are several contributors of information and several users who access the information using the interfaces provided. The System uses the power of the semi-structured data model by using it as the underlying model while abstracting it from the end users – both the contributors and the users. The FLEXIS system handles the gathering, storing and retrieval of information through separate modules. The Information Gathering Module of FLEXIS is designed to collect diverse information from a collection of contributors (akin to publishers in a publisher-subscriber scenario) and model them in some form or schema to be stored by the Information Storing Module. This involves providing the contributors (who are typically end users) an interface that is both user-friendly and can wrap the data in a convenient form (an XML document). The information gathering system has in a database, a collection of “editors” which can reasonably model the kind of information posted on the system. Since one of the main objectives of the FLEXIS system is to provide flexibility in the kind of information
