Fourth Generation Fourth Generation TechniquesTechniques

BY Deepika ChaudharyBY Deepika Chaudhary

Fourth generation Fourth generation techniques (4GT)techniques (4GT) The term .fourth generation techniques The term .fourth generation techniques

compasses a broad array of software tools that compasses a broad array of software tools that have one thing in common: each enables the have one thing in common: each enables the s/ware engineer to specify some characteristic s/ware engineer to specify some characteristic of the software at a higher level. The tool then of the software at a higher level. The tool then automatically generates source code based on automatically generates source code based on the developer.s specifications.the developer.s specifications.

Currently, a software development Currently, a software development environment that supports the 4GT model environment that supports the 4GT model includes some or all of the following tools: includes some or all of the following tools: nonprocedural languages for database query, nonprocedural languages for database query, report generation, data report generation, data manipulation, screen interaction and definition, code generation, high-level graphics

Contd..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.

Contd…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:

Advantages & Advantages & DisadvantagesDisadvantages Advantages: Dramatic reduction in software

development time. Improved productivity for software

developers. Disadvantages: Not much easier to use as

compared to programming languages.

4GL-Programming 4GL-Programming LanguageLanguage A A fourth-generation fourth-generation

programming languageprogramming language((1970s-1970s-19901990) (abbreviated ) (abbreviated 4GL4GL) is a ) is a programming languageprogramming language or or programming environment programming environment designed with a specific purpose in designed with a specific purpose in mind, such as the development of mind, such as the development of commercial business software commercial business software

A number of different types of 4GLs exist:A number of different types of 4GLs exist:

Report generatorsReport generators take a description of the data format and take a description of the data format and the report to generate and from that they either the report to generate and from that they either generate the required report directly or they generate a generate the required report directly or they generate a program to generate the report. program to generate the report.

Similarly, Similarly, forms generatorsforms generators manage online interactions manage online interactions with the application system users or generate programs with the application system users or generate programs to do so. to do so.

More ambitious 4GLs (sometimes termed More ambitious 4GLs (sometimes termed fourth fourth generation environmentsgeneration environments) attempt to automatically ) attempt to automatically generate whole systems from the outputs of generate whole systems from the outputs of CASECASE tools, tools, specifications of screens and reports, and possibly also specifications of screens and reports, and possibly also the specification of some additional processing logic. the specification of some additional processing logic.

Data managementData management 4GLs such as 4GLs such as SASSAS, , SPSSSPSS and and StataStata provide provide sophisticated sophisticated commandscommands for data manipulation, file for data manipulation, file reshaping, case selection and data documentation in the reshaping, case selection and data documentation in the preparation of data for preparation of data for statistical analysisstatistical analysis and reporting. and reporting.

Cont…Cont…

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

Some successful Some successful fourth-generation fourth-generation languages languages General Use / Versatile General Use / Versatile FortéForté

TOOL (transactional object-oriented langu TOOL (transactional object-oriented language)age)

SheerPower4GLSheerPower4GL (Microsoft Windows Only) (Microsoft Windows Only) PowerBuilderPowerBuilder WinDevWinDev DataFlexDataFlex Visual Visual DataFlexDataFlex (Microsoft Windows Only) (Microsoft Windows Only)

Database Database query languagesquery languages

FOCUSFOCUS NATURALNATURAL Informix-4GLInformix-4GL Genero Genero Progress 4GLProgress 4GL SQLSQL SB+/SB+/SystemBuilderSystemBuilder

Report generators Report generators

BuildProfessionalBuildProfessional GEMBaseGEMBase IDL-PV/WAVE IDL-PV/WAVE LINCLINC MetafontMetafont NATURALNATURAL Oracle ReportsOracle Reports PostScriptPostScript Progress 4GLProgress 4GL Query/Results Query/Results RPG-IIRPG-II Gauss Gauss

GUIGUI creators creators

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