Application software prototyping and fourth generation languages
G E. Fisher · 1987
Application prototyping is a technique used to define requirements and specify constraints on a proposed software system.It is based on the premise that, in a wide range of problem domains (particularly on-line interactive systems) users of the proposed application do not have a concrete idea of what the application should do, nor how it should operate.This report is designed as an introduction to the planning, organizing, executing, and controlling of a methodology for application prototyping.Senior level technical personnel and project management who are interested in instituting a prototyping program will benefit from this information.The methodology combines application prototyping and Fourth Generation Languages (4GLs) into a cogent and viable software life cycle designed to acknowledge the inherent difficulty in specifying software requirements.Often, after a system is operational, errors or shortcomings overlooked during development become evident.Application prototyping attempts to overcome these problems by providing users and developers an effective means to communicate ideas and requirements before a significant amount of effort has been expended in development.The prototyping process results in a functional set of specifications that can be fully analyzed and understood by users, developers, and management in deciding whether the application can be developed, and how it should be developed. The influx of Fourth Generation Languages has induced many organizations to undertake projects based on prototyping techniques.4GLs provide many of the capabilities necessary for prototype development, such as those described in NBS Special Publication 500-138, A Functional Model for Fourth Generation Languages.These capabilities include user functions for defining and managing the user/machine interface, data management functions for organizing and controlling access to data, and system functions for defining execution control and interfaces between the application and its physical environment.The benefits of the proposed methodology are the abilities to 1) identify requirements and problem areas in early development phases, 2) reduce the development time through reuse of the prototype or through knowledge gained in developing and using the prototype, and 3) produce systems based on true, rather than perceived, requirements.The combination of application prototyping and Fourth Generation Languages provides a cost-effective and controllable method of developing and maintaining software.vi 1.