4 parallel streams of activity:

Case studies:

Vehicle Cruise Controller Simulation (VCCS)

Railway Station Animation

Digital Watch Simulation

Tutorial Introduction to Software Tools

Practical exercises, based on a cricket and railway simulation

Seminars

Timetable

Introductions to Personnel

Assignments

Sources:

• papers

[B92] and references therein

Booch, Deutsch, Backus, Harel, Cantwell-Smith, Baldwin

• books

William James, Lamb, Davis

• software

public files in the ~wmb/public/demos directory

sources for the translators and interpreters

• documentation

eden and scout, theses

online documentation is accessible on www via the

Empirical Modelling

link in the Software Research section for the Dept entry

WHY? motivation & philosophy

issues

VCCS as a case study WHAT?

techniques

HOW? software prototypes

Tutorials

problems of general-purpose parallel programming

bound up with fundamental issues and concepts

in concurrent systems modelling

can't be properly addressed

in the traditional mathematical manner by

"abstracting away from the application"

concerned with relationship between form and content

and content involves real-world illustrations:

the electronic cat- flap, the railway station animation

the room layout, the cricket simulation etc.

get new perspective on programming in general

and parallel programming in particular

BUT – warning!

• won't always directly address

concurrency / conventional programming

Software case-study considered by Booch and Deutsch

Our version due to Ian Bridge and Simon Yung

Source available in ~wmb/public/demos/cruise

Dynamic model of vehicle <--> family of Eden files (ref main.e)

Visualisation and interface file is cruise.s.

Two ways to view:

Animation of requirements for reactive system.

Exercise in engineering design and simulation.

Construct and animate agent-oriented model by:

A definitive notation

is a simple formal language

used for expressing scripts of definitions of the form:

variable = function of other variables and constants.

Warning! definition ia a technical term in this module

and we (ab?)use the term definitive to mean "definition-based"

Definitive notations characterised by

• the types of the variables on the LHS

• the operators that can occur on the RHS

Values of the variables <--> observable quantities

introduce a new definition

In the cruise.s file, scout, donald and eden definitions are

differentiated via the %scout, %donald and %eden annotations.

Have X-application tkeden combining scout, donald and eden.

For practical work, use

tkeden <inputfile>

Pipeline approach still useful for

Examples of scout and donald extracts from the script:

< the SPEEDO window >

<the speedometer specification>

cf conventional engineering prototyping:

uses a special-purpose notation LSD

to represent the interfaces between agents

uses scout, donald and eden definitive scripts

..... VCCS model = eden program, but conceptually

design is specified at a higher-level of abstraction

LSD specification animated in main.e and associated files

This describes the dynamic model of the vehicle.

The screen display is described by the scout and donald scripts in cruise.s.

These enable the designer to inspect

VCCS specification

≠ logical model of the circumscribed system behaviour

VCCS specification

= an approximate representation of a particular state –

resembling a set of experimental observations –

incorporating information about the expected effect

of changing a parameter in the experiment.

Concerned with

incomplete and uncertain knowledge

that is being acquired through experiment

and not

comprehensive and reliable knowledge

that has been acquired from experiment.

"observable"

= value in a physical system being modelled

in principle measurable by some appropriate experiment.

Designer

• knows state of the system in terms of all such observables

• considers effect of changing parameters <--> observables

[Important distinction between

what agent can observe, and what agent can change]

Designer experiments:

change sampling rate of speed transducer

modify the layout of the speedometer

change mode of speed visualisation etc.

In principle – even in real engineering:

designer can treat every observable as a parameter

In practice doesn't make much sense to do so!

For example, don't usually change the force of gravity, or make the length of the vehicle inversely proportional to its speed.

Definitive script for VCCS

= a record of all observables of the system,

represented by variables in the script.

Redefinition of a variable = "changing a parameter".

In principle, any redefinition is interpretable

but only certain redefinitions are meaningful.

VCCS script is a means to expressing knowledge

developing the script is not a completed process

Can be used and viewed in many ways, not nec preconceived

e.g. many different views of the vehicle cruise control system.

Default: state of the system (the "global state")

= comprehensive set of observables conceived by the designer

But

state to be understood relative to

a particular agent and to context for observation

e.g. IS state of the screen display

= layout of the windows and form of the graphical objects?

IF SO, relevant observables are scout / donald definitions

OR is state of the display conceived via behaviour over time

IF SO, consider speed and position of the vehicle etc.

Characteristic set of observables associated with each agent

determines the state of the system relative to that agent.

Actions of an agent <--> privileges to change certain parameters

Illustrations:

How the speedometer script is interpreted: the designer agent.

How forces act in the model:

M EDEN DoNaLD

EDEN

T LSD SCOUT

SCOUT-DoNaLD-EDEN

W LSD

Th ADM SCOUT-DoNaLD-EDEN

LSD-ADM-EDEN

... a conflict between two engineering cultures [Brödner]

One position, ... the "closed world" paradigm, suggests that all real-world phenomena, the properties and relations of its objects, can ultimately, and at least in principle, be transformed by human cognition into objectified, explicitly stated, propositional knowledge.

The counterposition, ... the "open development" paradigm ... contests the completeness of this knowledge. In contrast, it assumes the primary existence of practical experience, a body of tacit knowledge grown with a person's acting in the world. This can be transformed into explicit theoretical knowledge under specific circumstances and to a principally limited extent only .... Human interaction with the environment, thus, unfolds a dialectic of form and process through which practical experience is partly formalized and objectified as language, tools or machines (i.e. form) the use of which, in turn, produces new experience (i.e. process) as basis for further objectification.

empirical -> theoretical

observed -> believed

... developing skills, theories and instruments

State cf mode (p32 Lamb)

mode = set of states