Data Access Interface System and Data Pair
Discussion on Data Access Interface System and Data Object Model (BEAT 1.0)
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Article index:
Pre -: concept
Preface: look back
I. Discussion on the data access interface system
Open Client / Open Server
2. ODBC (Open Database Connectivity: Open Database Connection)
3. OLE DB (Object Link and Embedding Database)
4. JDBC (Java Database Connectivity: Java Database Connection)
Second, data object model discussions (to be continued) Appendix: US Famous Database Product Notepad (Reference)
The research database theory is to design a better database system. To clarify the development, feature of the data access interface system and the data object model, which helps to develop a better data application system. Pre -: concept
Database: A integrated data repository that meets information requirements for one or more organizations, multiple users. (Define a set of database elements: integration, sharing, storage, information)
Database Management System (DBMS): Targets for processing all users of the software system for data inventory (it has two major parts: database control subsystem and data stock storage subsystem)
Database system: The sum of the hardware and software system based on database applications (mainly including database, dbms,
Distributed Database System: Database is divided into logic associations and physically scattered data subsets of different sites, and provides a database system that fully operates the data accessibility capabilities of these subsets.
Preface: look back
In the early 1980s, Vulcan (DBASEII's predecessor) became the first database system implemented on the microcomputer and is widely popular. Subsequent XBase families (DBASE series, FoxBase series, low version foxpro, etc.), paradox, clipper from a In terms of a low-level database system (in semantics, it is appropriate to express the database system. However, from the performance, system design, the database management system is described more appropriate. At that time the database management system More than the "Apply Level" program that is developed for managing a lot of information. And Oracle, DB2, etc., there is no microcomputer version. At this time, the system is far from the modern database system. Of course, this is the target or said it is User demand is determined. The user's operations of the database based on XBase and other non-standard database systems (originally, although they also have the characteristics of programming languages such as the function library, but they are more like operational commands. Until these systems It provides compilation or pseudo-compilation capability
Note 1 :: = From the following note table, the problem about compilation is different in the database system, the key is that the database interaction is interactive: whether it is SQL. On the other hand, the database system is positioned. Personal Think: XBase, Paradox, Clipper and other series products achieve distributed but have not implemented C / S structures and more limited to the use of local databases and Oracle, Sybase SQL Server, Sybase System, DB2, Informix, etc. The positioning of the database system is different. They adhere to the previous design concept, and more importantly, the emergence of C / S structures naturally leads to more modern (of course, the current commercial application development model should be multi-layer distributed Data System Development Model (with the appearance of the client development tool PowerBuilder, Visual Basic, DEPHIL, and auxiliary design software products) At the same time, the DBMS's dilasted and the previous database system peripheral software products can work even integrate at the client. Among the client development tools. Previous terminal-server (Host System) database system ends. You can "tampered" data server system clients appear. This appearance of data system applications should be critical, it makes data The use, performance, and even the management of the database, etc., and XBase, Paradox and other systems have seen their establishment of local database management, design and data system application development, from all levels of compilation. As the functionality embodied in DBMS, the DBMS of the C / S architecture is achieved. It is also the sentence adhering to the previous design concept. Although the data access interface system we explore should be targeting C / S structure and more advanced database system architecture However, I have previously mentioned the ultimate goal of this article is to help program designers design better data application systems. This way we need to pay attention to earlier database management systems and other languages (assembly, c, cobol, pascal, FORTRAN et al. To interact. Before before and after (92 years ago, see the following << US Famous Database Products Note >>), each famous database system product achieves SQL according to its own structural system and positioning (in the realization situation Nature has different. Xbase family, Parodox, etc. add SQL interaction interface and implements mixing of XBase language and SQL. And Oracle, Sybase, Informix and other systems have extended SQL according to their own system needs to form their own data manipulation language) And compile or pseudo-compilation or pre-compilation capacity or call library. The two capabilities described above have greatly affected the interaction of database systems and applications. However, the interaction is different from the current program designer consciousness. The relationship between the application and the database system. Total Body, there may be several cases of database system and application interactions: 1. The database management system provides access to the application to enhance the functionality of the database management system. Second, the application utilizes the database files transformed into the format. Of course, You can access unconverted database files through other methods. Third, the data manipulation language embeds other programming languages (called host language). In fact, IBM-IMS database system implemented in 1969 (Data manipulation language DL / I) already has this function. Natural system needs to provide a precompiled interface. IV, use the database system to use the repository (such as Oracle OCI Library, it is worth mentioning "OCI Library in the latest interface system Also use). From the point of view of the current data system programming, it is not a database file that can be used in your program. In the two ways of using the database file, one is not needed to master the database file format structure. Natural, the four listed above are summarized from different database systems.
For the design of the database system itself, the design of the data system program is also the significance of the C / S structure, because it makes the future "world" difference.
Overall, the C / S structure appears, almost all tasks related to the data application are completed by the host of the diverse database management system, and the early data performance is basically completed on the host. And the database system and the external interaction are very limited. Although although , Distributed, Host systems, and other technologies have changed on the above.
Early, C / S structure core idea is task decomposition, embodying the computing mode of client requests and server responses. It has multiple modes: SC / SS, MC / SS, SC / MS, LC / S, and basic structure It can also constitute a complex structure.
The basic structure of C / S is illustrated below. In the natural C / S structure, the client interacts with the server, the middleware (data access interface) (data access interface), which must be enabled. And it is our topic - Data Access Interface (Data Object) The concept of the model has not appeared in this time). We do not expand the knowledge of the intermediate parts and data server architecture. We focus on the (dedicated) database middleware for C / S structure database system services. From the figure You can see two: Microsoft's ODBC, IBM's DRDA. Actually, the famous Sybase's Open Client / Open Server database dedicated middleware. As time, there is still a SUN that is often used so far.
JDBC, Microsoft OLE-DB. Below we will explore the data object model under several data access interface systems and corresponding systems (of course, there is no object model in a specific period).
to be continued:
I. Discussion on the data access interface system
Open Client / Open Server
2. ODBC (Open Database Connectivity: Open Database Connection)
3. OLE DB (Object Link and Embedding Database)
4. JDBC (Java Database Connectivity: Java Database Connection)
Second, data object model discussions (to be continued) Appendix: US Famous Database Product Notepad (Reference)
