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Database Systems Laboratory

/ Subhash Bhalla / Associate Professor

Current developments in the area of data modeling and information systems' design aim to capture a wide variety of applications into the fold of DBMS (Database Management System) technology. This is due to improved understanding of information extracted from databases by the usage of advanced DBMS techniques. The DBMSs currently use visual representations within new interfaces to manage large volumes of data, and also to manage data that may have complex features associated with its structure. In addition to complexity in features, such as multiple attributed data, wave-forms and multi-dimensional orientation, many new types of raw data are emerging that need to be captured by DBMSs for the purpose of information extraction. Among these, the image data and video image data are two important forms of data and many research efforts are being made to make suitable DBMS architectures for image and video databases.

In order to provide flexibility in terms of data representation, the databases need the support of powerful data-modelling techniques. Most of the advances in techniques concentrate on capturing more meaning within data that is made resident on a computer system. Within this framework, a number of researchers are actively developing improved data management strategies. The database systems laboratory aims to participate in research activity to promote Database utilization for new applications.

The laboratory has activity in progress in the area of transaction processing and modelling of data objects for new applications. In case of new applications, different applications have varying needs in terms of data representation and operations that need to be performed. Many applications add many types of transactions and many types of processing constraints.

The transaction processing environments occurring in various applications include, real-time systems, distributed database systems, main-memory resident systems, distributed heterogeneous database systems, and applications requiring complex data representations based on Object-Oriented databases. The transaction management issues among various application environments consider successful completion of user transactions. There are a number of transaction processing domains being explored by researchers in this line of activity. These include - long duration transactions, nested transactions, time-critical transactions, distributed computing, committing transactions in the event of failures, and management of replicated databases.

There is a continuing evolution of computer systems as a hierarchy of computing elements that cooperate to perform computations. In addition complex software systems also introduce multiple layers of software. Thus, the activity of performance evaluation of transaction processing systems is an important area that provides improved understanding of systems. This facilitates improved integration and refinement in technique.

The Database Systems Laboratory has research activity concentrating on data modelling as well as transaction processing activity. This activity will most likely be useful for the next generation of multimedia database systems.

Data Modelling for Complex Objects Information Processing Systems of future will be a combination of integrated components. There will be components for intelligent problem solving, or decision making, components for specialized data processing (e.g., image enhancers), and components for shared information management. The applications will utilize a shared base of information. The examples of some of the application domains are business automation, industrial automation, computer-aided design and manufacture, and cartography. Under the ``Data Modelling for Complex Objects" the new approaches for representing such objects are being explored. Among these relation of graphics and databases is being studied.

Real-Time Databases One of the new challenging area of interest in transaction management is that of Real-time database systems in which transactions have time constraint. Within the new environment, the database management system must support a mix of ordinary as well as real-time transactions. The transaction support must also be highly reliable and fast.

Traditional approaches to transaction management introduce elements of unpredictable delays during transaction processing. Thus, making these not suitable for adoption in new application environments. Many new approaches that are more appropriate for the new environment are being studied.

Refereed Journal Papers

  1. P. Krishna Reddy and Subhash Bhalla. A nonblocking transaction data flow graph based protocol for replicated databases. IEEE Trans. on Knowledge and Data Engg., 7(5):829--834, 1995.

    Replicated data management systems adopt the 1-copy serializability criteria for processing transactions. In order to achieve this goal, many approaches rely on obtaining votes from other sites for processing update requests. In the proposed approach, a technique for generation of a data access precedence graph for execution of a transaction is analyzed. The data flow graph approach is a distributed system approach. The technique, is free from deadlocks, and avoids resubmission of transactions.

Refereed Proceeding Papers

  1. Harvey Abramson, Subhash Bhalla, Kiel Christianson, James Goodwin, Janet Goodwin, and John Sarraile. Towards cd-rom based Japanese - English dictionaries: Justification and some implementation issues. In Natural Language Processing Pacific Rim Symposium, 95, Seoul, Korea, Dec. 1995. SIG-KLC, and SIG-NLP of IPSJ(Information Processing Society of Japan), and KISS (Korean Information Science Society).

    Japanese orthography is very difficult and presents many problems to the student of the language. In order to cope with the problems connected with the study of Japanese we are led to the notion of `hyper-dictionary', a general multi-lingual, multimedia database. We discuss some of the issues connected with a CD-ROM implementation of a Japanese $ <-> $ English hyper-dictionary. The idea of hyper-dictionary, however, is very general and not restricted to any particular language or languages.


  1. Subhash Bhalla, editor. Information Systems and Data Management, volume 1006 of Lecture Notes in Computer Science. Springer-Verlag, Heidelberg, Germany, 1995.

Academic Activities

  1. Subhash Bhalla, 1995. Refereed Papers for the CGIC.

  2. Subhash Bhalla, 1995. Member of Indian Association for Research in Computer Science, Bombay, India.

Next: Information Systems Laboratory Up: Department of Computer Previous: Performance Evaluation Laboratory
November 1996