While several learning support systems that visualize program behaviors for various object-oriented languages have been developed to date, many of them are not sufficient for learners to understand the concepts specif...
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ISBN:
(纸本)9789869721493
While several learning support systems that visualize program behaviors for various object-oriented languages have been developed to date, many of them are not sufficient for learners to understand the concepts specific to object-oriented languages. We have developed a program visualization system that supports learners' understanding by visualizing relationships among objects and classes. We evaluated the effectiveness of our system by introducing it into an actual class and measuring the degree of improvement in learners' understanding based on tests. The evaluation results suggest that our system would have a certain degree of effectiveness for learning programming using object-oriented languages.
The emergence of the object-oriented (OO) methodology has shown its capabilities in modelling the real world better than the earlier relational methodology. However, object-oriented databases (OODBs) are still conside...
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The emergence of the object-oriented (OO) methodology has shown its capabilities in modelling the real world better than the earlier relational methodology. However, object-oriented databases (OODBs) are still considered immature in comparison with relational databases (RDBs) which have existed for many years. RDBs still continue to dominate the implementation of databases constituting more than 90% of all database implementations [28]. It was felt worthwhile to exploit the great modelling power of OO methodology, while still facilitating relational implementations. These reasons have led us to develop an object-relational transformation methodology [20-25] which allows us to use the OO methodology for data modelling and to transform it into a relational logical model for implementation in relational database management systems (RDBMSs). The main purpose of this paper is to present a performance evaluation of the transformation methodology. The evaluation covers I/O cost models of different types of queries. The type of evaluation is basically comparison-based, in which the performance of SQL operations upon a set of tables derived from the relational data model is compared with the tables derived from the OO data model using the transformation methodology. The results of the evaluation show that the performance of the RDB implementation transferred from an OO conceptualmodel using our object-relational transformation methodology is better than the relational implementation using a conventional relational modelling. Moreover, in many cases, the relational modelling is not applicable since it cannot capture the design semantics particularly relating to collection types. Our object-relational methodology solves this problem. (C) 2001 Elsevier Science B.V. All rights reserved.
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