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:*<b>UML data model</b>. UML class diagrams are often proposed to express database schemas. The ability of this formalism to describe conceptual schemas has been studied in references [R02-01] and [B09]. It appears that by discarding some ill-designed constructs and by adding a small number of constructs (such as identifiers and other basic constraints) it is possible de define a variant of UML (called DB-UML) quite fitted to database schemas. DB-UML has also been implemented in the DB-MAIN CASE tool, together with bi-directional global schema transformations with the DB-MAIN GER model. | :*<b>UML data model</b>. UML class diagrams are often proposed to express database schemas. The ability of this formalism to describe conceptual schemas has been studied in references [R02-01] and [B09]. It appears that by discarding some ill-designed constructs and by adding a small number of constructs (such as identifiers and other basic constraints) it is possible de define a variant of UML (called DB-UML) quite fitted to database schemas. DB-UML has also been implemented in the DB-MAIN CASE tool, together with bi-directional global schema transformations with the DB-MAIN GER model. | ||
:*<b>Virtual data models</b>. Several architectures have been based on the concept of ''wrapper''. A wrapper is a software component attached to a data source (file, spreadsheet, database, web page) and that provides its users (typically application programs) with a data model that is different from that of the data source. A wrapper forms a virtual DBMS that offers a virtual data model as well as a virtual data manipulation language (to some extent, JDBC, ODBS and ADO are generic wrappers). Wrappers have been used as natural interfaces to network databases [P81-01], as building blocks in federated databases [P01-03] and in an evolutive migration architecture allowing easy conversion of application programs [P08-05]. Normally, a wrapper simulates a new technology on top of a legacy data manager [P01-03]. In the latter application, ''inverse wrappers'' simulate the legacy technology (typically CODASYL or standard files) on top of an SQL DBMS in order to minimize the source code adaptation [P04-04]. | :*<b>Virtual data models</b>. Several architectures have been based on the concept of ''wrapper''. A wrapper is a software component attached to a data source (file, spreadsheet, database, web page) and that provides its users (typically application programs) with a data model that is different from that of the data source. A wrapper forms a virtual DBMS that offers a virtual data model as well as a virtual data manipulation language (to some extent, JDBC, ODBS and ADO are generic wrappers). Wrappers have been used as natural interfaces to network databases [P81-01], as building blocks in federated databases [P01-03] and in an evolutive migration architecture allowing easy conversion of application programs [P08-05]. Normally, a wrapper simulates a new technology on top of a legacy data manager [P01-03]. In the latter application, ''inverse wrappers'' simulate the legacy technology (typically CODASYL or standard files) on top of an SQL DBMS in order to minimize the source code adaptation [P04-04]. | ||
| − | :Let's finally mention an interesting proposal by Yannis to optimize the graphical layout of large ER schemas based on three physical laws (electricity, magnetism, mechanics)[P05-06]. | + | :Let's finally mention an interesting proposal by Yannis Tzitzikas to optimize the graphical layout of large ER schemas based on three physical laws (electricity, magnetism, mechanics)[P05-06]. |
*'''Keywords''' | *'''Keywords''' | ||
:ER model, Individual model, Merise model, UML class diagrams, wide-spectrum model, GER model, DB-MAIN model, logical data model, temporal model, legacy data model, relational model, network model, hierarchical model, OO model, OR model, XML model, large schema layout, semantic and statistical aspects of models, IS-A relation | :ER model, Individual model, Merise model, UML class diagrams, wide-spectrum model, GER model, DB-MAIN model, logical data model, temporal model, legacy data model, relational model, network model, hierarchical model, OO model, OR model, XML model, large schema layout, semantic and statistical aspects of models, IS-A relation | ||
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