4GL
The fourth generation language or 4GL for short is the term used for programming languages or programming environments of the fourth generation. These are designed to be able to write functions or complete applications for a specific application area quickly - with as few lines of code as possible .
The term 4GL is not precisely defined and is mainly used for marketing purposes. However, the main common goal of all 4GLs is to achieve the same functionality with less code compared to third generation languages . The term was used extensively in the 1980s, often referring to application-specific scripting or query languages such as SQL as 4GL languages that were set on a specific topic . Later the term Rapid Application Development (RAD) was used with overlapping semantics . In the meantime it is becoming more and more evident that application-specific script languages are only the input for a 4GL language. That is, the actual 4GL language is used to specify a system which in turn can interpret a specific scripting language. So-called parser generators make it possible to define a separate script language for each purpose and to transform the scripts created with them into the source text of a third-generation high-level language. Since an application-specific script language essentially always serves to define a specific model of a certain topic, one has recently been talking about model- centered software development or model-driven software development .
With the first languages of the third generation (e.g. Fortran , Pascal and C ) the introduction of standardized control structures was in the foreground. This was followed by the creation of extensive program libraries with additional modules, as they often occur in specialized applications. The following object-oriented programming languages such as C ++ and Java are still 3GL languages, but brought major improvements in software structuring. At the same time, more and more graphic editors were created whose semantics were optimized for certain areas of application in order to simplify access to the associated program libraries. In particularly successful cases, a so-called visual language was created with the graphic editors . Since these could no longer be clearly assigned to the high-level languages of the third generation, these were often already referred to as 4GL language, whereby no distinction was made between the actual "language" and the system that can interpret such a language.
The name 4GL was strongly promoted by James Martin . He first used it in 1982 in his book Application Development Without Programmers . However, this interpretation has only really come into play in recent times with model-driven software development.
Goal setting
- Reduction of development effort through the use of more understandable, application-related paradigms .
- Better maintainability and expandability of the programs through better readability and user-friendly presentation
- resulting in a reduction in development times and costs
Types
- Report generators
- Input form generators
- Complete systems that take information from CASE systems and generate entire systems with report and input generators and further information on process logic. One example of this is James Martin's Information Engineering tool , which allows the results of system analysis and system design to be recorded (in the form of data flow diagrams , entity relationship diagrams and entity life cycle diagrams). Hundreds of thousands of COBOL program lines were then generated from this.
- Generation of parts or entire software systems from application-specific models of the industry, e.g. B. with AUTOSAR .