Classifications

Overview

Since it is difficult to nail down what exactly a 4GL is, this section deals with how we may classify 4gls.

We can not simply define what a 4GL is !

Their roots are not academic as was the case with 3GL,s. They have been created by software houses & entrepreneurs

No true standardisation

In many instances a 4GL will fit into more than one classification.

Pure

for example: to produce a report:

LIST CUSTOMERS LAST_NAME FIRST_NAME

WHERE LAST_NAME EQUALS "SMITH"

Use of code generation & tried & tested templates etc. can decrease development time

Can not cope with all business problems eg. would require a template for all situations

Hybrid

Type	Facilities	Problem Solution	Production Solution	Usage	User-type
Pure	Non-procedural eg. spreadsheets	Specification of problem statement	Problem statement transformed to procedural solution by generator	Dedicated or specialist tools	End-users or analysts (possibly programmers)
Hybrid	Non-procedural & procedural	As above & coding in procedural language	As above & translation of procedural code	Often general purpose but may be dedicated	End-users or analysts & programmers

End user

Aimed at the non-professional, often computer literate user

Professional

For programmers and/or analysts or the analyst/programmer

Information Centre

Data management based
Aimed at the end-user and the analyst
Maintained by a Data Administrator
for example; ease of use facilities rather than ability to build complex systems

Development Centre

Dedicated

General Purpose

Decision Support

Not to be used in mainstream data processing tasks, also dedicated
eg. sales reporting, modelling

Mainstream DP