VLP: a visual language for prototyping

Specifications of information-systems-type applications are often based on the use of entity-relationship (ER) and dataflow (DF) diagrams, which cover the conceptual modeling of data and functions, respectively. VLP, an executable visual language for formal specifications which fully integrates ER and DF diagrams in a semantically clear way, is introduced. Unlike existing commercial products (the so-called CASE tools), which can only support good-quality documentation, simple forms of consistency checking and bookkeeping, VLP supports executable specifications, which provide a prototype of the desired application. After reviewing the principles of VLP, the structure of the ECASET environment in which VLP is embedded is outlined. How the environment supports the stepwise derivation of specifications, from informal to formal, is shown, as well as how it supports specification-in-the-large