Discussion on data access interface system and data object Model--[1]

Object | access | data | system


data access interface system and data to





 




Discussion on
data access interface system and data object Model (Beat 1.0)





81_RedStar81@163.com





TomHornson.student@www.sina.com.cn





Personal Anthology:





http://www.csdn.net/develop/author/netauthor/RedStar81/





 





 





 





Article index:





Pre: Concept





Preface: Looking Back on the history





the discussion of data access interface System





1. Open Client/open Server





2. ODBC (Open DB Connectivity: Open database connection)





3. OLE DB (Object Link and embedding DataBase)





4. JDBC (Java database Connectivity:java db connection)





second, data object model discussion (to be continued)


Appendix: US Famous Database product Chronicle (reference)





           





 





Research Database theory is to design a better database system. It is helpful to develop a better data application system by clarifying the development, characteristics and differences between data access interface system and data object model.





Pre: Concept





 





database: An integrated data repository that satisfies the information requirements of one or more organizations and multiple users. (defines a set of database elements: integration, sharing, storage, information)





Database management System (DBMS): A software system that aims to process all user requirements for database access (it has two main parts: the database control subsystem and the database storage subsystem)





database system: The sum of hardware and software system based on database application. (including database, DBMS, < non-DBMS software::, < Integrated database management software::)





< non-DBMS software:: = functional parts That work with the DBMS but are not part of the DBMS. Mainly include: Operating system, programming language and corresponding compiling system, data communication system, various applications (with database management system interaction to serve the user).





< Integrated data management software:: = auxiliary and coordinate the functions of DBMS, generally not used independently, always integrated with DBMS, developed on the base of DBMS. such as automatic report generation program, database application development program, database test program, database aided design program, Data conversion facilities and so on.





Distributed Database systems: Databases are divided into logical associations that are physically dispersed across different sites, and provide a database system that fully operates the data access capabilities of these subsets.





 





Preface: Looking Back on the history





 





in the early 80, Vulcan (the predecessor of Dbaseii) became the first database system to be implemented on microcomputers and was widely popular. Subsequently, the famous Xbase family (dBASE series, Foxbase series, low version FoxPro, etc.), Paradox, Clipper is, in a sense, a low-level database system (semantically, it is appropriate to use a database system to express this. However, it is more suitable to use database management system to describe the performance and system design. The database management system at the time was more like the "application level" developed for managing a lot of information. program). and Oracle, DB2, etc. at this time there is no computer version. At this time the system is far less complex than the modern database system. Of course, this is determined by the target of the system or by the user's needs. The user's operations on the database are based on xbase and other non-standard data manipulation languages of various database systems (initially, although they also have features such as library programming languages, they More like an operation command. Until these systems provide the ability to compile or pseudo compile < Note 1::> is truly considered a language.





Note 1::= from the following chronicle table, the questions about compilation differ in each database system, and the key is the database interaction language on which they are based: SQL. On the other hand, it is the location of the database system. Personally think: XBase, Paradox, Clipper and other products to some extent to achieve a distributed but has not implemented C/s structure and more limited to the use of local database with Oracle, Sybase SQL Server, Sybase System, DB2, The positioning of database systems such as Informix is different. They uphold the previous design concept, but also more important is: the emergence of C/s structure has naturally led to a more modern (of course, the current business application development model should be said to be multi-layer distributed) Data System development model ( As witnessed by the advent of client development tools PowerBuilder, Visual Basic, Dephil, and assistive design software products. At the same time, the functionality of the DBMS is detailed and the peripheral software products of the previous database system can be worked on the client or even integrated into the client development tools. The previous terminal-server (host system) database system ended. Can "usurp" Many of the capabilities of the data server system clients appear. The emergence of data system applications should be critical, making the use, performance, and even database management of data a huge change. and Xbase, Paradox and other systems since the implementation of different levels of compilation capabilities to see that they set the local database management, Design and Data System application development equals one, they are the functions that the DBMS embodies and different DBMS that implement the C/S architecture. Or is that sentence adhering to the previous design concept.





 





Although we explore the data access interface system should be for C/s structure and more advanced Database system architecture, however, as I mentioned earlier, the ultimate goal of this article is to help program designers design better data application systems. So we need to focus on the earlier database management system and other languages (assembly, C , Cobol,pascal,fortran, etc.). back and forth (92 ago, see below << U.S. famous Database product Chronicle >>), the well-known database system products according to their own structural system and positioning have implemented SQL ( The realization of the situation is naturally different. The Xbase family, Parodox, and so on have increased the SQL interface and implemented a mixture of xbase language and SQL. and Oracle, Sybase, Informix and other systems to expand SQL according to the needs of their respective systems to form their own data manipulation language. and compile or pseudo compile or precompile capabilities or call libraries. The implementation of the two capabilities described above has had a significant impact on the interaction between the database system and the application. But the interaction at that time was different from the relationship between the application and the database system in the program designer's consciousness. In general, there may be several situations in which a database system interacts with an application: a , the database management system provides access to the application to enhance the functionality of the database management system. Second, the application uses the format transformation of the database files. Of course, you can access the unmodified database files through other methods. Third, the data manipulation language is embedded in other programming languages (called Host languages). In fact, the Ibm-ims database system (dl/i), which was implemented in 1969, already has this function. The natural system needs to provide a precompiled interface. Four, use the database system to provide the call library in the application (such as Oracle's OCI library, it is worth mentioning that the OCI library is still used in the newest interface system). And from the point of view of the data system programmer, What you can use in your program is nothing more than a database file. In two ways of using database files, one does not require you to master the database file format structure. Naturally, the four scenarios listed above are summarized from different database systems.





for the database system itself, especially for the design of the data System program is also for many aspects, the meaning of C/s structure is significant. Because it makes the future "world" different.





Overall, before the C/s structure appeared, almost all the tasks related to data applications are performed by the hosts hosting the database management system, and the early performance of the data is basically done on the mainframe. And the database system has very limited interaction with the outside world. Although the distributed, host system and other technologies have changed this.




At the early stage of
, the core idea of C/s structure is task decomposition, which embodies the computing mode of client request and server response. It has many modes: Sc/ss, Mc/ss, Sc/ms, L C/S, and the basic structure can form complex structure.





Below is an illustration of the basic structure of C/s. In the natural C/s structure, the client interacts with the server and must act as a bridging middleware (data access interface). And it's just our theme-The data access interface (the concept of the data object model is not present at this time). The knowledge of middleware and data server architecture is not discussed here. We focus on the (dedicated) database middleware for the C/s structure database system.





from the diagram you can see two kinds: Microsoft's ODBC, IBM's DRDA. In fact, it is also known as Sybase's Open client/open Server database-specific middleware. As time goes by so far, there are Sun's
.




JDBC, Microsoft Ole-db. Below we discuss several data access interface systems and the data object model of the corresponding system (of course some of the systems have no object model at a certain time).

















 





 














to be continued:





 











the discussion of data access interface System





1. Open Client/open Server





2. ODBC (Open DB Connectivity: Open database connection)





3. OLE DB (Object Link and embedding DataBase)





4. JDBC (Java database Connectivity:java db connection)





second, data object model discussion (to be continued)


Appendix: US Famous Database product Chronicle (reference)