外文翻譯-對象技術-全文預覽
【正文】 r applications that will be used for many years, during which pany needs may change and make software modifications necessary. Software reliability can be improved by objectoriented programming. Since the objects are repeatedly tested in a variety of applications, bugs are more likely to be found and corrected. Objectoriented programming also has potential benefits in parallel processing. Execution speed under object oriented methods will improve with parallel processing. Objectoriented DBMS A shift toward objectoriented DBMSs does not have to replace relational DNMS. As its name implies, it is orientation rather than a fullblown DBMS model. As such, it can blend with and build on the relational schema. Objectoriented DBMSs integrate a variety of realworld data types –such as business procedures and policies, graphics, pictures, voice, and an nontated text. Current relational products are not equipped to handle them efficiently. Data types in RDBMSs are more monly recordoriented and expressed in numbers and text. Object orientation also makes contributions to application development efficiency. It XIII makes the data function, attributes, and relationships an integral part of the object. In this way, objects can be reused and replicated. You can query the data on its functions, attributes, and relationships. By contrast, most RDBMSs demand that the knowledge associated with the data be written into and maintained separately in each application program. Object orientation is going to be available in two forms: one for those who need and want a radical change, and one for those who want some of its advantages without going through a major conversion. The first form of objectoriented DBMS focused largely on the puteraided design (CAD) market, which needed to store plex data types such as the graphics involved with an aircraft design. The second form is made up of the leading RDBMS vendors who support the concept of integrating object management capabilities whit their current line of relational products. Sybase, Inc, the first vendor to introduce an objectoriented capability, offers Sybase , which enables the user to program a limited number of business procedures along with the data types in a server’s database engine . Any client attempting a transaction that does not conform to these procedures is simply rejected by the database. That capability enables users to shorten the development cycle, since integrity logic and business rules no longer need to be programmed into each application. This approach reduces maintenance costs as well, since any changes in the procedure can be made once at the server level instead of several times within all the affected applications. Last, the serverlevel procedures increase the system’s performance, since the operations
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