A process oriented simulation model specification and documentation language

Abstract

We present a language for specifying and documenting discrete event simulation models, designed to facilitate communication during model design, implementation and maintenance. The systems from which models are developed are viewed as collections of communicating elements. Each element is specified separately in a module consisting of attributes, axioms and a scenario. The model's specification consists of each model element's specification and some systemwide attributes and axioms. Synchronization among model elements (model dynamics) is specified within the model elements rather than globally. Each language control structure has a monitor associated with it. Appropriate changes are made in the model's state in response to a monitor's sensing an attribute change. The language contains a library of specifications for common simulation model entities such as the priority queue. The syntax and semantics of the language are presented through examples. Examples of a library specification and a model specification are included. This paper proposes a discrete event simulation model specification and documentation language (SMSDL) for human to human communication. The language is designed to be a readable, writable,' useful tool for human, not machine, use. We suggest that the language may be used by managers, technical people who are not programmers and model program implementers. It can be useful at every stage of modelling-from model design to model program maintenance and from problem specification to decision making based on the outcome of modelling. The language allows multiple levels of detail, each suitable for a particular audience.The language is designed to accomplish three things:1. Encourage people to writd (and read) a document; 2. Ensure unambiguous communication among writers and readers; 3. Give a writable way of expressing model dynamics, whose proper description is considered a major problem in model description.Our solution to 1 and 2 is an almost formal language which provides unambiguous communication, but one as close to natural language as possible, with certain informalities allowed to encourage its use. We deal with 3 by expressing synchronization implicitly rather than by inventing (or borrowing) some explicit synchronization notation that could discourage use of this language except by technical people who are at ease with formalisms used for very specific purposes.

The entity - connection approach to modelling and simulation

“…Later it was discovered that not only the implementation phase but also the model specification and documentation phases need some supporting tools. Consequently, simulation model specification and documentation languages (SMSDL) were developed [Frankowski/Franta 1980]. Such languages enhance the stepwise refinement technique and may typically be transformed automatically into standard simulation languages (e.g.…”

A specification language to assist in analysis of discrete event simulation models

“…Kleine describes an SMSDL which, by progressive refinement, is intended to lead to executable Simscript programs [23]. Frankowski and Franta propose a process (and Simula) oriented SMSDL [14]. As with Kleine, a specification evolves into an implementation; the same language is used for both.…”

“…Our approach is to construct a model specification in a formal language which can be analyzed for diagnostic purposes and which can be transformed through additional analysis into an efficient model implementation (probably in a different language). Several authors have suggested the process concept [4,14,221 or Simscript's entity-attribute-set approach [27] as a basis for modeling methodologies. While neither provides a theory supporting the simulation process, both provide powerful representational and conceptual tools for model specification.…”

Effective Design and Use of Computer Decision Models

“…Languages can be used that are self-documenting, that is, they are comprehensive to the user without additional information [5,11,21], This feature is a further enhancement of a simulation language, for it allows the user the opportunity to become wellversed in the language with a minimum amount of training time. Access to an external database is of value to some users [17].…”