A multidatabase system implementation on CORBA

2001

In this work, a method for generating external schemas in object oriented databases in the ODMG framework is proposed. External schema generation involves obtaining all the relationships existing between the classes selected to make up an external schema. This generation process is part of an external schema definition system that we are developing, which allows the definition of external schemas in ODMG. External schemas generated with this process do not extend the object-oriented paradigm and, the generation of unnecessary intermediate classes is avoided.

We provide a principled extension of SQL, called SchemaSQL , that offers the capability of uni- form manipulation of data and meta-data in re- lational multi-database systems. We develop a precise syntax and semantics of SchemaSQL in a manner that extends traditional SQL syntax and semantics, and demonstrate the following. (1) SchemaSQL retains the flavour of SQL while sup- porting querying of both data and meta-data. (2) It can be used to represent data in a database in a structure substantially different from origi- nal database, in which data and meta-data may be interchanged. (3) It also permits the cre- ation of views whose schema is dynamically de- pendent on the contents of the input instance. (4) While aggregation in SQL is restricted to values occurring in one column at a time, SchemaSQL permits "horizontal" aggregation and even aggre- gation over more general "blocks" of informa- tion. (5) SchemaSQL provides a great facility for interoperability and dat...

OOIS 2000, 2001

ODMG 3.0 (January 2000) does not specify how to define external schemas in object oriented databases and only offers a very basic mechanism for defining views, called named queries. In this paper, a system and a language for defining external schemas in ODMG databases are presented. Both are based on a mechanism that avoids the generation of classes that are not necessary in external schemas. The proposed language is an extension of ODMG ODL and allows the definition of external schemas using the ODMG named queries for defining derived classes. Nevertheless, the proposed language is independent of the derived classes definition mechanism used.

ACM Transactions on Database Systems, 2001

We provide a principled extension of SQL, called SchemaSQL, that offers the capability of uniform manipulation of data and schema in relational multidatabase systems. We develop a precise syntax and semantics of SchemaSQL in a manner that extends traditional SQL syntax and semantics, and demonstrate the following. (1) SchemaSQL retains the flavor of SQL while supporting querying of both data

Concurrency and Computation: Practice and Experience, 2001

The First ECOOP Workshop on Object-oriented Databases was held on June 15, 1999, in Lisboa, Portugal, in conjunction with the Thirteenth European Conference on Object-oriented Programming.

IEEE Transactions on Knowledge and Data Engineering, 1999

ÐObject-oriented database system (OODB) supports an object-oriented data model with the functionality of persistency and transaction semantics. In order to facilitate the use of OODB, the Object Database Management Group (ODMG) defined a standard for object database management system. On the other hand, the Object Management Group (OMG) defined the Common Object Request Broker Architecture (CORBA), which is an emerging standard of distributed object technology providing the interconnection network between distributed objects. For the sake of matching these two object models, taking the advantages of merging both of them, and building a more sophisticated infrastructure, the integration of CORBA and OODB is currently an urgent and important issue in distributed object systems. Instead of using Object Database Adapter (ODA) suggested by the ODMG, in this paper, we provide a novel way of reusing the Object Transaction Service (OTS) and wrapping techniques to introduce OODB into CORBA automatically. Through our design, CORBA clients or OODB object implementers do not need to learn any knowledge of each other. In addition, error recovery is also provided to guarantee the consistency of object states. The whole task for integrating CORBA and OODB is done transparently by our proposed preprocessor, which plays an important role in solving problems encountered by ORB and OODB vendors easily.

Users extract knowledge from the database by posing Quires. Most of the users submit SQL Query to extract information from the database. This makes a restriction on users to be familiar with SQL tool. Our proposal is to integrate the existing different database schemas into a single common format. It is widely recognized that integration of database and information retrieval is gaining more importance recently. To enable convenient access to the data organized in different database schemas, we have proposed a new Heterogeneous Data Base Connectivity (HDBC) architecture with graphical user interaction that can be used even by a novice person to create, manipulate and extract information in any database schema. The proposed algorithm also gives provision to export table from one database to another and supports excellent searching capabilities. User friendly interaction is ensured and hence this work enables the end user to retrieve information in an efficient manner from the database organized in different schema and can easily integrate and share the processed information across different applications.

Arxiv preprint arXiv:0912.0603, 2009

- One of the challenging problems in the multidatabase systems is to find the most viable solution to the problem of interoperability of distributed heterogeneous autonomous local component databases. This has resulted in the creation of a global schema over set of these local ...

IEEE Computer, 1992

T he Zeitgeist object-oriented database management systems, developed by Texas Instruments between 1985 and 1990,' supported applications in computer-aided design and manufacturing, software engineering, knowledge representation, and hypermedia systems. From the Zeitgeist project, we learned that these applications have widely varying database management needs. We concluded that such applications would be better served by an open, extensible object-oriented database (OODB) management system, whose functionality could be tailored, rather than by a single monolithic database management system. Our conclusions are consonant with other research and development

Proceedings of The IEEE, 1987

Object Oriented Systems, 1996

Computer Standards & Interfaces, 2003

CORBA is widely accepted as the open international standard for modelling and building comprehensive distributed systems. In most cases, CORBA architects have adopted relational databases for storage of persistent data. Among the issues that usually face architecture designers considering how to combine CORBA and standard relational database standards are fault tolerance, performance, and the extensibility and scalability of the systems. The research team involved with this paper found that the ODMG object database concept is useful to solve the issues encountered when integrating CORBA and relational database standards. The reference architecture, which the team devises, integrates CORBA and relational databases without compromise on the necessary transactional properties. The CORBA standard object transaction service and concurrency control service are reused. The team also develop an object relational data modelling tool-Latte-that supports the overall design intention as well the development paradigms for the proposed architecture. The implementation of the system is useful to CORBA, ODMG, and relational database architects because it provides a unified modelling and programming paradigm capable of solving the problems of managing mission-critical distributed data. Thus, we present a case study of combining different international standards to build a comprehensive system.

1997

Innovative changes have been taking place in information technology for a few decades. Due to the rapid evolution in this area, the demand for innovation in this area is much higher than elsewhere. This requires large effort of companies to respond quickly to market conditions in order to organize work and conduct business more efficiently. In particular, companies have to reengineer existing form of new key technologies like WWW or E-Commerce. This article deals with the transformation of a relational database to an object database. It suggests a new solution based on database and model-driven engineering integration. In the first part it is discussed in general issues of relational database transformation into object one, some problematic areas are identified. Subsequently, depending on detailed analyse of the database reverse engineering processes, the whole process is defined as a sequence of models and transformation among them based on model driven architecture (MDA). Some of the models are based on generally accepted standards. The proposed approach comes also with its own models. The paper defines not only their exact structure but also abstracts its own algorithms used during their development. The final part contains an experimental verification of the proposed procedures with a particular example and summary of the results. However, the new object model and the existing relational database's model usually do not go well together. In other words, a large semantic gap between both models must be bridged. The approach proposed in this paper is database migration. Basically, this approach comprises two tasks. In the first task, the Traditional relational database Schema is reengineered. The schema is transformed into a well-designed and intuitively understandable object oriented schema conforming to ODMG standards which the new applications can adapt. Afterwards, the data are (automatically) migrated into an object oriented DBMS.

Information and Software Technology, 2001

This paper reports on a graphical interface, OgDesk, for object-oriented database systems (OODBs). It orthogonally supports the activities of ² Browsing types and instances ² Creating and maintaining instances ² Creating, using and programming with graphical representations of single type queries ² Creation, maintenance and evolution of the schema.