in general a 4GL programming language contains constructs that allow programmers to express system logic to computer systems in a manner closer to natural language than earlier languages.
One statement in a fourth-generation language such as PROGRESS typically corresponds to many lines of code in a third-generation language such as C, COBOL or Fortran. Most 4GLs are used to access databases.
All 4GLs are designed to reduce programming effort, the time it takes to develop software, and the cost of software development.
fourth generation: ABAP/4 - and IDMS/COBOL
ABAP/4 is the programming language used for the thousand tiny embedded programs called transactions that make up the application.
ABAP is code written in an interpretive language similar to COBOL in syntax.
so in order to allows SAP customers to extend the functionality of the base product ABAP was developed in 4th generation language.
u can find more explanation in the following site:
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. In the evolution of computing, the 4GL followed the 3GL in an upward trend toward higher abstraction and statement power. The 4GL was followed by efforts to define and use a 5GL.
The natural-language, block-structured mode of the third-generation programming languages improved the process of software development. However, 3GL development methods can be slow and error-prone. It became clear that some applications could be developed more rapidly by adding a higher-level programming language and methodology which would generate the equivalent of very complicated 3GL instructions with fewer errors. In some senses, software engineering arose to handle 3GL development. 4GL and 5GL projects are more oriented toward problem solving and systems engineering.
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 as was seen with MARK-IV and MAPPER (see History Section, Santa Fe real-time tracking of their freight cars - the productivity gains were estimated to be 8 times over COBOL). The usability improvements obtained by some 4GLs (and their environment) allowed better exploration for heuristic solutions than did the 3GL.
A quantitative definition of 4GL has been set by Capers Jones, as part of his work on function point analysis. Jones defines the various generations of programming languages in terms of developer productivity, measured in function points per staff-month. A 4GL is defined as a language that supports 12 - 20 FP/SM. This correlates with about 16 - 27 lines of code per function point implemented in a 4GL.
Fourth-generation languages have often been compared to domain-specific programming languages (DSLs). Some researchers state that 4GLs are a sub-set of DSLs. Given the persistence of assembly language even now in advanced development environments (MS Studio), one expects that a system ought to be a mixture of all the generations, with only very limited use of the first.
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.
Some 4GLs have integrated tools which allow for the easy specification of all the required information:
James Martin's own Information Engineering systems development methodology was automated to allow the input of the results of system analysis and design in the form of data flow diagrams, entity relationship diagrams, entity life history diagrams etc from which hundreds of thousands of lines of COBOL would be generated overnight.
More recently Oracle Corporation's Oracle Designer and Oracle Developer 4GL products could be integrated to produce database definitions and the forms and reports programs.
Some successful fourth-generation languages
General Use / Versatile
IBM VisualAgen/VisualAge Generator
Forté TOOL (transactional object-oriented language)
SheerPower4GL (Microsoft Windows Only)
Visual DataFlex (Microsoft Windows Only)
Database query languages
Progress 4GL Query/Results
Data manipulation, analysis, and reporting languages
Clarion Programming Language
ADS/Online (plus transaction processing)
Audit Command Language
MAPPER (Unisys/Sperry) now part of BIS
MARK-IV (Sterling/Informatics) now VISION:BUILDER of CA
Database driven GUI Application Development
Screen painters and generators
FOURGEN CASE Tools for Rapid Application Development by Gillani
Progress 4GL ProVision
4th Dimension (Software)
Progress 4GL AppBuilder
Revolution programming language
Web development languagues
Reward Points if found helpfull..
abap is the fouth generation language because of all
applications are write on the application server and execute
on the server only.all reports are done by using the
advanced business language.
by using abap language we r connecting to data base.
those languages which are connecting to data base they are
4 th generation languages.
[Fourth-generation programming language|http://en.wikipedia.org/wiki/4GL]
Reward Points if useful.