1. Fourth Generation Techniques
BY Deepika Chaudhary

2. Fourth generation techniques (4GT)
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 4GT 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

3. Contd..
Like all other models, 4GT 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 4GT tool can use. Thus, the client/developer dialog remains an essential part of the development process.

5. Contd…
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 4GT model has both merits and demerits. These are enumerated below:

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

7. 4GL-Programming Language
A fourth-generation programming language(1970s-1990) (abbreviated 4GL) is a programming language or programming environment designed with a specific purpose in mind, such as the development of commercial business software

8. A number of different types of 4GLs exist:
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.
Similarly, forms generators manage online interactions with the application system users or generate programs to do so.
More ambitious 4GLs (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.
Data management 4GLs such as SAS, SPSS and Stata provide sophisticated commands for data manipulation, file reshaping, case selection and data documentation in the preparation of data for statistical analysis and reporting.

9. Cont…
All 4GLs 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 4GL can be spectacularly successful

10. Some successful fourth-generation languages
General Use / Versatile
Forté TOOL (transactional object-oriented language)
SheerPower4GL (Microsoft Windows Only)
PowerBuilder
WinDev
DataFlex
Visual DataFlex (Microsoft Windows Only)

11. Database query languages
FOCUS
NATURAL
Informix-4GL
Genero
Progress 4GL
SQL
SB+/SystemBuilder

12. Report generators BuildProfessional GEMBase IDL-PV/WAVE LINC Metafont
NATURAL
Oracle Reports
PostScript
Progress 4GL Query/Results
RPG-II
Gauss

13. GUI creators 4th Dimension (Software) eDeveloper MATLAB's GUIDE
Omnis Studio
OpenROAD
Progress 4GL AppBuilder
Revolution programming language