A NOVEL APPROACH IN DESIGN AND DEVELOPMENT OF OBJECT-ORIENTED HETEROGENEOUS DISTRIBUTED DATABASE MANAGEMENT SYSTEM

Abstract

Object-Oriented Heterogeneous Distributed Database Management Systems (OOHDDBMS) are used to handle databases using the object-oriented programming (OOP) philosophy in a wide range of application domain, such as, running with different kinds of Database Management Systems, and using different programming languages. Object-Oriented Query languages (OOQLs) are more powerful than the relational query languages which are used widely. Here a new OOHDDBMS named, GURU is designed and imple mented to supplement the various problems faced with OOQLs, which are available with research prototypes only. To tackle this problem, a new OOQL named, GSQL is designed and implemented which provides userfriendliness and runs the complete popular ANSI standard SQL (Structured Query Language) designed for relational database systems. Apart from this, GSQL supports its own powerful Object-Oriented Programming Language with semantic constructs. GSQL compiler uses its own (used with GURU) translator/mapper to support heterogeneous programming languages through GURU'S shell. The existing systems do not have the intelligent local query mechanism with object-oriented support which can work with different indexes automatically. We have presented an approach to handle data definition language part with intelligence to support queries in heterogeneous environment for the quick replies. This scheme helps in maintaining the perfect consistency of the database with the intelligent design of schema. The local schema is derived from the global schema and the site autonomy is preserved accordingly. The heterogeneous database fragments are designed to provide the maximum access efficiency at the local sites. An approach is suggested which integrates the heterogeneous schemas and provide the environment design accord ingly, for handling an application at different remote terminal nodes with different database management systems. A design of translator/mapper is presented which helps in a heterogeneous global domain. A process known as user application registration is illustrated which is very helpful in the integration of the schemas. Further, a concept of cooperative system is provided, which helps network terminal nodes for the maintenance of appli cations on the global network with a modified master/slave con cept. An intelligent server design is presented which uses the knowledgebase to provide the different fragment allocation schemes with the available knowledge using trigger methods. The server helps the different other blocks like Object Manager, Data Manager etc. to coordinate the proper fragment handling opera tions. A concept of general object is presented which uses no files and no messages in the system. The different complexity measures are suggested. Later, the different ways are suggested, using them the complexity can be reduced considerably. A concept of message-task is explained, which is used to provide great power to handle objects. The messages are sched- uled like normal tasks by GURU and the burden on Operating System, to create separate processes and execute message-task is reduced. The three different layers are explained which are associated with GURU. These layers have the individual assigned tasks to maintain the isolation among the system, network and the fc. application tasks for the better privacy, security and operation al efficiency. A dynamically changing environment with changing object structures is proposed with no limits for the changes. The support of metaclass concept is also illustrated. There need not be any prior proposed ways in which the structure of the objects can be changed. The different thread and trigger mechanisms are suggested to trace the active objects and maintain the required consistency in the system. The concept of intensional and extensional notions are explained with GURU and the both notions are used with the proposed object structure in GURU. Further, the designs of object manager and data managers are explained which maintain the different versions of the objects and the database fragments used as objects. A concept of virtual object and object migration is explained with GURU. The different privacy and security arrangements are explained with the dynamically changing object structures. The tight security with a new concept of extended object structure is provided which also helps in the protection of the object's view. The suggested methods use the object's privacy locks with embed ded data in the object's structure. Some other information can also be used to relax locking dynamically, which extends a wide range of userfriendliness in the system. GURU has been developed in C language, which consists of about 60,000 lines source code. A comparative study of GURU with the other existing DBMSs has been made.