A Students Project in the Field of “Human Machine Interaction in

Realtime“

Klaus Bothe

8th Workshop “Software Engineering Education and Reverse Engineering” Durres, Albania, 8th – 13rd September 2008

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Organisation of educational project work with a real-life software system

Introduction to this case study of a software system

Presentation addresses two issues:

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Overview

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Background: Organisational issues

• Winter semester 2007/08: project seminar for students

• Students project: 24 students 8 teams

• Joint project seminar of Institute of Psychology

(Prof. H. Wandke, Engineering Psychologie)

and Institute of Informatics (K. Bothe)

• Participants from staff (presenters, organisation):

- Informatik: Klaus Bothe, Uli Sacklowski,

Nicolas Niestroj, Jochen Heyden (students)

- Psychology: Hartmut Wandke, Knut Polkehn,

Jens Nachtwei, Achim Warning (PhD students)

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Background: History and goals

• Pratice-oriented real-life projects: supported by our

curriculum at HU

• Students profit from that: real customer, new application

area ...

• Existing software system ATEO developed by staff from

psychology

and informatics students

• Used in experimental psychology for research

• ATEO with several drawbacks, e.g. missing documents like

requirements specification, too complicated software

architecture …

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HMI software ATEO in our DAAD project?

• Another case study for software projects

(after SemOrg, XCTL …)

• Example of introducing real-life projects in

education,

e.g. by giving working task for students

• Invitation for reuse, reimplementation, extension

HMI = Human Machine Interaction

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ATEO:

a nice comprehensible case study in the application area of psychology

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ATEO system:Software controls experiments (1)

Sequence of experiments

One subject Two subjects

Observer

Central experiment

Baseline experiment 1

Baseline experiment 2

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ATEO system:Software controls experiments (2)

Goal

Car

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Working place as a photograph: drivers – observer

Drivers: by joystick determine velocity and direction

Observer: view of drivers, street with car -> give commands (visual, acustical)

Wall

Camera

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Input buttons of the observer

Observer: select driver

Observer: give commands (visual, acustical) to the selcted driver

Activates a prepared mp3 file

E.g “faster”

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ATEO system:Background are automated assistence

systems

Sequence of experiments

Observer

Central experiment

Baseline experiment 1

Baseline experiment 2

E.g. driver in a car

E.g. pilot and co-pilot in a

plane

In perspective: automated assistance

system

One subject Two subjects

In this experiment:

human

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ATEO:

what to do with it in a students project

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Reverse engineering project: Existing software to be documented and assessed

ATEO:Smalltalk

Requirements specification

Software architecture: components …

Test cases

User handbook

SW quality criteria:Modifyability,Reusability of components(Structure of SW ok?)

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Additional students activities

ATEO:Smalltalk

Team-work

Interdisciplinary work

Understand a new application field

Learn a new object-oriented programming language: Smalltalk

Software in interdisciplinary projects of our group:- Institute of Physics at HU (XCTL): C++- Leipniz Institute: Fortran 70, 90, 95- Hahn-Meitner-Institute: Turbo Pascal LabView (visual programming language)- Siemens (Diploma theses): C#

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Tasks in the seminar

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Overview of tasks

Task 1: 7. November 2007: Develop a use case diagram and a requirements specification of the ATEO system (external behaviour)

Task 2: 29. November 2007: ATEO program: Understand and document the implementation (each team only one class)

Task 3: 19. December 2007: Find and assess the real software architecture of the ATEO-System; make a proposal for a better one

Task 4: 23./30. January 2008- Extend the requirements specification according to user wishes

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Waterfall model:documents considered in the project

Analysisand

Definition

Analysisand

Definition

DesignDesign

ImplementationImplementation

TestTest

MaintenanceMaintenance

External behaviour:Requirementsspecification...

Structure of softwareSoftware

Architecture

Program code:commented ...

Test cases …

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Task 1:

Develop a use case diagram and a requirements specification

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Use cases:

completely different solutions from different groups;not decidable: which is the best solution?

Use cases – main errors:

- not suitable use cases - too detailed use cases - actors with wrong rights

Task 1: Develop a use case diagram

and …

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Pair of object persons (drivers)

Operateur (observer)

Experiment leader

Drive the car

Give navigationshints

Prepare and supervise the

experiment

Write protocol file

<<include>>

<<include>>

Use case diagram of ATEO: final result of discussion

Switch on the camera

Built-upconvenientparcours

Evaluateprotocol file

Scientiest(Psychologist)

<<include>>

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Requirements specification:

sources were some verbal text in a students manuscript, the externally observable behaviour, questioning of psychologists

Requirements specification:results very promising, functional and non-functional requirements addressed, couples of open questions fixed

Summary: Students very motivated by that application area

Task 1: Develop … a requirements

specification

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Result: see File

Task 1: Develop … a requirements

specification

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Task 2:

Understand and document the ATEO implementation

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Task 2: Understand and document the ATEO implementation

Subtasks: Learn fundamentals of Smalltalk:

Motivation: Java well-known: on that basis, learn a new oo language

Smalltalk: one of the 7 most known OO languages (Java, C++, C#, Delphi, Eiffel, Simula 67)

Smalltalk: innovative concepts have been introduced (Extreme Programming, Refactoring, SUnit ...)

Work with Squeak as a programming environment for Smalltalk;Modern programming environment:

- Syntax-directed browser - integrated debugging- integrated versioning (like: cvs)- Interpretation (virtual code like Java JVM) combined with automated

incremental compilation (thus, compilation not visible)

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Differences between Smalltalk and Java

Smalltalk: New concepts compared with Java - type-less language (dynamic typing) - visibility: all methods visible, all variables hidden - global variables (contradiction to OO) - Strong object-oriented language: even elementary data types are classes - no difference between class and object (classes are objects, too) - different syntax: x:=1, parameter passing ...

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Task 3:

Find and assess the real software architecture of the ATEO-System;

make a proposal for a better one

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Task 3: Find and assess the real software architecture of the ATEO-System; make a proposal for a better one.

Documented as a UML class diagram

Developed by open source UML tools: ArgoUML, Dia

SW architecture not atomatically derived by the tool (Smalltalk) manual and semi-automatic derivation

Rather good solutions, including assessment of the architecture: see later

Initial motivation by the staff useful: see next two slides

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Software architecture: the project may fail

“The Importance of Software Architecture Software architecture forms the backbone for any

successful software-intensive system. An architecture is the primary carrier of a software system's quality attributes such as performance or reliability. The right architecture - correctly designed to meet its quality attribute requirements, clearly documented, and conscientiously evaluated - is the linchpin for software project success. The wrong one is a recipe for guaranteed disaster.”

(Website: Software Engineering Institute (SEI), Carnegie Mellon University)

Motivation

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Real architecture of XCTL (Inst. Physics)

SW Architecture:Influences quality features:- comprehensibility- Re-usability of components in

another environment- Maintainablity- Security- testability - ...

Motivation

Source: Kay Schützler, Dissertation

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Task 3:

a) Find … the real software architecture …

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Group 6Relations between ATEO classes,morphs, global variabls

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Group 1

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Gruppe 1Relations between the 8 core ATEO classes …

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Relations between the 8 core ATEO classes: without attributes and operations

Gruppe 8

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Task 3:

b) Assess … the real software architecture …

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Group 8

End node class

Direktcycle

Conclusion:5 classes are connected by cycles, i.e. they cannot be understood , re-used, modified, and separetly tested as independent components(ATEOTastaturabfragen,ATEOrealJoystickstepping, ATEOPar …) can be handled only as a set of classes

cycle in three steps

End node class*)

*) but not quite sure: global variables may cause additional relations between classes

Relations between the 8 core ATEO classes: architecture problems

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Global variables: cohesion and coupling

Smalltalk (global variables)CarID AnteilMB1 u.a.

.

Globals considered harmful:

(E. Klimas …: Smalltalk with Style)

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Task 3:

c) make a proposal for a better software architecture

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Steuerhard-warezugriff

Tastatur, Joystick

Dateizugriff

Versuchsablauf-

steuerung

Versuchs-konfiguration

Logdatei

MorphFahrzeug

MorphStreckeMorphConfig

Group 1Hierarchical layered architecture

Layer 2: user interface

Layer 1: functionality

Layer 0: data and hardware

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Group8Hierarchical layered architecture

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Task 4:

Extend the requirements specification according to user wishes

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Task 4: Extend the requirements specification according to user wishes

Measures: Teams connected to some of the use

cases Consultations between students and

psychologists

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Pair of experiment persons (drivers)

Operateur (observer)

Experiment leader

Drive the car

Give navigationshints

Prepare and supervise the

experiment

Write protocol file

<<include>>

<<include>>

Switch on the camera

Built-upconvenientparcours

Evaluateprotocol file

Scientiest(Psychologist)

<<include>>

Groups assigned to the use cases(2)

Kamera-übertragung einschalten

Group 4

Group 2

Group 3

Group 6

Group 8

Group 1

Group 5

Group 7

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Task 4: Extend the requirements specification according to user wishes

Results: Teams present their solutions in a

seminar followed by a discussion Extended requirements form the basis

for current diploma theses

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Conclusions

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Suitability of the ATEO system in education

• ATEO is a convenient case study in an application

area:

comprehensible also for informatics students

• ATEO: motivating application area for the students

• ATEO: like many systems in practice: most serious

problem is the bad software architecture; hard to repair;

certainly a reimplementation necessary; possibly also

refactoring is applicable (Fowler, 2000)

• Smalltalk is a mature OO language; Java would be

better for our students (1st language)

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ATEO: Main problems and what to do?

SW architecture: - some parts well-defined; however, many others chaotic- bad for maintenance and extension- the hardest challenge of the system: the bottleneck of the whole system

Smalltalk: A comparable Java solution would be valuable

Open: test case selection, automatization of regression testing

Some diploma thesis under work, e.g.- new working place for the operateur

- network version (three working places for three actors) - evaluation of protocol files

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ATEO: System demonstration on the basis of Smalltalk and Squeak