Fourth Generation Techniques BY Deepika Chaudhary Fourth generation

Fourth Generation Techniques BY Deepika Chaudhary

Fourth generation techniques (4 GT) n n The term. fourth generation techniques compasses a broad array of software tools that have one thing in common: each enables the s/ware engineer to specify some characteristic of the software at a higher level. The tool then automatically generates source code based on the developer. s specifications. Currently, a software development environment that supports the 4 GT model includes some or all of the following tools: nonprocedural languages for database query, report generation, data manipulation, screen interaction and definition, code generation, high-level graphics

Contd. . n Like all other models, 4 GT begins with a requirements gathering phase. Ideally, the customer would describe the requirements, which are directly translated into an operational prototype. Practically, however, the client may be unsure of the requirements, may be ambiguous in his specs or may be unable to specify information in a manner that a 4 GT tool can use. Thus, the client/developer dialog remains an essential part of the development process.

Contd… n For small applications, it may be possible to move directly from the requirements gathering phase to the implementation phase using a nonprocedural fourth generation language. However for larger projects a design strategy is necessary. Otherwise, the same difficulties are likely to arise as with conventional approaches. As with all other models, the 4 GT model has both merits and demerits. These are enumerated below:

Advantages & Disadvantages Advantages: n Dramatic reduction in software development time. n Improved productivity for software developers. n Disadvantages: n Not much easier to use as compared to programming languages. n

4 GL-Programming Language n A fourth-generation programming language(1970 s-1990) (abbreviated 4 GL) is a programming language or programming environment designed with a specific purpose in mind, such as the development of commercial business software

n A number of different types of 4 GLs exist: n Report generators take a description of the data format and the report to generate and from that they either generate the required report directly or they generate a program to generate the report. n Similarly, forms generators manage online interactions with the application system users or generate programs to do so. n More ambitious 4 GLs (sometimes termed fourth generation environments) attempt to automatically generate whole systems from the outputs of CASE tools, specifications of screens and reports, and possibly also the specification of some additional processing logic.

Cont… n All 4 GLs are designed to reduce programming effort, the time it takes to develop software, and the cost of software development. They are not always successful in this task, sometimes resulting in inelegant and unmaintainable code. However, given the right problem, the use of an appropriate 4 GL can be spectacularly successful

Some successful fourthgeneration languages n n n n General Use / Versatile Forté TOOL (transactional object-oriented language) Sheer. Power 4 GL (Microsoft Windows Only) Power. Builder Win. Dev Data. Flex Visual Data. Flex (Microsoft Windows Only)

Database query languages n n n n FOCUS NATURAL Informix-4 GL Genero Progress 4 GL SQL SB+/System. Builder

Report generators n n n Build. Professional GEMBase IDL-PV/WAVE LINC Metafont NATURAL Oracle Reports Post. Script Progress 4 GL Query/Results RPG-II Gauss

GUI creators 4 th Dimension (Software) n e. Developer n MATLAB's GUIDE n Omnis Studio n Open. ROAD n Progress 4 GL App. Builder n Revolution programming language n