HP 3000 Manuals HP 3000 Manuals
Chapter 1 Introduction General Overview TurboIMAGE/XL is a set of programs and procedures that you can use to define, create, access, and maintain a database. A database is a collection of logically-related files containing both data and structural information. Pointers within the database allow you to gain access to related data and to index data across files. The primary benefit of the TurboIMAGE/XL database management system is time savings. These savings are typically provided in the following areas: * Data security * Rapid data retrieval and formatting * Program development * Program maintenance * Program file independence * File consolidation * Special information needs This chapter describes each of these topics in detail. Effective use of TurboIMAGE/XL can remove a large portion of the overhead associated with integrated system design from application analysts and programmers. TurboIMAGE/XL can channel system design talents into functional rather than structurally-supportive design tasks. Data Security Conventional file management systems have limited data security provisions. Access to computer readable data can only be denied to individuals with system access by providing physical protection for the media upon which the file is stored, such as using a data vault for storing sensitive data stored on magnetic tape or disk. TurboIMAGE/XL, in conjunction with MPE/iX, provides security at account, group, data item, and data set levels. Implementing security at the item level allows sensitive data to be stored online under the control of TurboIMAGE/XL, a database manager or designer, and system manager, with minimal regard for additional security provisions. TurboIMAGE/XL security provisions can limit programmer or operator access to sensitive information. Rapid Data Retrieval and Formatting Conventional file organization frequently requires using multiple file extracts, sorts, and report programs to produce meaningful output. Information requests frequently require weeks to implement, during which time the usefulness of the requested data can decrease. QUERY/3000, the Hewlett-Packard database inquiry facility, or user-written inquiry programs that use the TurboIMAGE/XL procedures, allow instant interrogation of the database by individuals with access to the system. Other ad-hoc reporting packages are also available. Program Development The database structure can be defined and built without using special purpose application level programming. Because control of the linkage portion of the database is under TurboIMAGE/XL software control, the programmer does not need to be concerned with testing the structure and can concentrate on the functional programming task. QUERY/3000 can be used to build test data, as well as to interrogate the results of program and system tests. This feature eliminates the requirement that file-related programs be completed before meaningful functional programs can be written. It is no longer necessary to hold up functional program testing until file building or file maintenance programs are completed. More modules of a given system can be tested at the same time. A specific benefit in the COBOL environment is program coding time. The programmer need only define File Division entries for those files that exist outside the control of TurboIMAGE/XL. Typically, such files are concerned with original entry into the processing cycle (data entry files) and with report files. All data under the control of TurboIMAGE/XL is implicitly defined in every program that accesses the database. The programmer need not code the Data Division entries associated with anything except the detail data used by a given program. The time savings generated in correct data definition the first time the program is coded, as well as in the correct description of the physical location of the data to be processed, will reap significant benefits in the program test cycle. Program Maintenance Throughout the life of a system, processing requirements evolve as the usefulness of the data is explored. As file organization concepts change with the needs of the application, some data restructuring can be done with little impact on existing programs. Changes to the structure of an existing database affect only those programs that process the changed data; no other programs in the system need to be recompiled to reflect the new database structure. The evolution of the database is not limited by the need to balance the cost of changing an existing system against the benefits to be derived from the new structure. It is not necessary to do a "where-used" evaluation on a data item carried in multiple files to assess the impact of a data change on existing systems. Finally, the accessibility of data is not limited by design decisions made during initial system design. The structure of a database can evolve with the needs of the application user. The application designer no longer has to anticipate the needs of the user across the full life of the system. Program File Independence Conventional file structures tend to be rigid and inflexible. The nature of conventional file management systems requires that the logic of application programs be intricately interwoven with file design. When it is necessary to alter the structure of a file, a program must be written to change the file and programs that access the file must be changed to reflect the file change. Because change is the rule rather than the exception in data processing, a large percentage of total time and manpower is spent reprogramming. TurboIMAGE/XL allows the data structure to be independent of the application program. Data item relationships are independently defined. Changes in the database structure need only be incorporated into those programs that manipulate the changed data. User programs need to view only that portion of the database description that pertains to each program's processing requirements. Because all references to the database are resolved at execution time, only those programs affected by changes to the database description need to be changed. File Consolidation Most information processing systems that serve more than one application area contain duplicate data. For example, a vendor's name can appear in an Inventory file, an Accounts Payable file, and an Address Label file. The data stored in these three files probably varies slightly from file to file, resulting not only in wasted file space but also inconsistent program output. Redundant and inconsistent information severely impedes any system's capacity to deal with large amounts of data. File consolidation into a database eliminates most data redundancy. Through the use of pointers, logically related items of information are chained together, even if they are physically separated. In the example of vendor names and addresses, only one set of data would be stored. Using logical associations, the data can be used by any program needing it. Because there is only one record to retrieve, the work required for data maintenance is greatly reduced. Finally, all reports drawn from that item of information are consistent. Special Information Needs The requirement for one-time information in a format that has never been requested is no longer a problem for data processing users. The user with a special data requirement can get to any subset of information on the database, frequently without the intervention of a programmer. Volatile analytical data requirements can be filled in a minimal amount of time by the people who need the data. The time savings in programming overhead and report specification generation can be enormous. Native Language Support (NLS/3000) can be used with TurboIMAGE/XL, which allows character sets other than US ASCII to be used in defining a database and allows data to be sorted in a database according to the local alphabet. NLS enhancements are recognized by four TurboIMAGE/XL utilities: DBSCHEMA, DBUTIL, DBUNLOAD, and DBLOAD. For more information on these utilities, refer to the NLS/3000 Reference Manual and chapters 6 and 8 in this manual.