TDT4252 Modelling of Information Systems Advanced Course

1

Sobah Abbas Petersen

Adjunct Associate Professor, NTNU

Researcher, Sintef

[email protected]

TDT4252Modelling of Information Systems

Advanced Course

TDT4252, Spring 2011Lecture 1: Introduction

2

Learning Goals (from Study Plan)

• Theoretical insights into different modeling perspectives, languages and techniques for creating models of :– Information systems – Enterprises

• Practical skills in – Analysing situations for modelling– Creating good models

• The course will introduce the ideas of Enterprise Modelling and provide a holistic view of modelling.


3

Background

• Lecturer: – Sobah Abbas Petersen (IDI/Sintef)

[email protected]

• Teaching Assistant:– Mohamed Asif

[email protected]

• Students (Questionnaire to be filled out, available from the Lecture Schedule page)– Study program

– Earlier courses

– Modelling experience

– Learning expectations


4

This week

• Information about the course• Motivation

– Why model?– Why take this course ?– Clarification of the scope of the course

• Historical Perspective on Modelling for Information Systems

• NB. The lectures will be conducted in English.• Please feel free to ask questions in Norwegian or

English.


5

Course Outline

• The course will consist of the following:– Perspectives of modelling and different modelling approaches and

languages.

– Enterprise Modelling and Active Knowledge Modelling (AKM) Approach

– Enterprise Architectures

• Assignments– There will be one mandatory assignment

• Evaluation– A written exam – 75%

– Assignment – 25%


6

Practical Information

• Course times:– Lectures

• Mondays 12:15 – 13:00hrs room MA21• Fridays 12:15 - 14:00hrs room F4

– Note: Lecture times may change, but students will be informed ahead of time.

– Exercises• Mondays 15:15 – 17:00hrs room F3

• Course material (articles and lecture presentations) available from:– Course homepage: http://www.idi.ntnu.no/emner/tdt4252/

– It’s Learning


7

Practical Information: mailing list

• There is a mailing list for the course. Please subscribe by

sending an email to [email protected]

• Mailing list is [email protected]


8

Curriculum

• The course curriculum is based on a collection of articles.

• Lectures and lecture notes are a part of the curriculum.

• Articles are available from the course homepage: (Lecture

Schedule and Reading List pages)

• The exercises should be done using the software

application Metis, version 5.2.2.


9

Assignment

• The mandatory assignment (worth 25% of the final grade) is built up of several modules.

• The assignment should include several sub-models that are linked:– This requires several modelling exercises that can eventually be put

together as one model.

– This requires thinking holistic and information as multi-dimensional.

– Important: this work is done throughout the semester, after each modelling approach is presented in the lectures.

• Deadline to be announced.


10

Lecture Plan(Note: will be updated shortly)


Lecture Lecture Exercise

weekWeek # Week start Week end Topics

Week curricula

Mondays 12:15-13:00, M21

Fridays12:15-15:00, F4

Mondays15:15-17:00, F3

2 1 10.jan 14.jan Introduction A01 Lecture

3 2 17.jan 21.janIntroduction to Modelling: Why model?Introduction to METIS Lecture Lecture

4 3 24.jan 28.jan Perspectives to Modelling Lecture

5 4 31.jan 04.feb No lecture

6 5 07.feb 11.feb i* Modelling Lecture Lecture

7 6 14.feb 18.feb Process Modelling Lecture Lecture

8 7 21.feb 25.feb Product Modelling Lecture Lecture

9 8 28.feb 04.marEnterprise ModellingIntroduction to AKM Lecture Lecture

10 9 07.mar 11.mar Enterprise Architecture Lecture Lecture



13 28.mar 01.apr

14 12 04.apr 08.apr Term Paper presentations

15 13 11.apr 15.apr Course Summary

16 14 18.apr 22.apr Easter

17 15 25.apr 29.apr Easter

11

Terminology

• Information systems:– “An information system is made of all the pieces of data and information

used/stored/processed for the needs of the users and applications of enterprises” (Vernadat 1996).

• Model:– A model is anything used in any way to represent anything else. It can be

a physical object, a mathematical or logical representation, a conceptualisation of something.

– It is more abstract, usually less comprehensive, and normally cheaper to create than what it models.

– It is important to select which parts to represent as a model.

• Conceptual Model:– A conceptual model represents 'concepts' (entities) and relationships

between them.


12

Terminology, contd.• Modelling Approach:

– A modelling approach consists of a non-empty set of semi-formal or formal languages and a number of rules for using these languages to construct models.

• Enterprise Model:– A consistent set of special purpose and complementary models describing

the various facets of an enterprise to satisfy some purpose of some business users.

• Holistic Model:– A model that takes into account the different aspects or views of the

situation or system modelled and how they may affect one another. e.g. the functional aspects, performance aspects, user interface aspects, etc.

• Model View– A specific aspect of a system or situation that is modelled, e.g. the

functional view of the system.– The contents of the model viewed a from a particular perspective, e.g. the

contents that a particular user is interested in.


13

Motivation (1)

• A model represents how people perceive an area or a domain.

• Enterprises and IS development are ready for modeling tasks.

• It is important to understand the mechanisms that are in play when modeling (alone or in a large group of people).

• Modeling is important for analysis and requirements specification:– Poor analysis and requirements specification work is frequently the

reason for the problems with software development.


14

Motivation (2)Who can benefit from this course?

• Everyone involved with enterprise and information system

development, especially those involved in what is traditionally termed

the ‘early’ phases of IS development.

• People working with choices and adaptations of development

methodology, modeling language or modeling tool in an organization.

• People working with the development of modeling environments.

• People who want to do research on information systems modeling at an

international level (e.g. in projects and master theses in the IS group, in

the university or in the research sector).


15

Why Model?• Modelling may be conducted for several

reasons in a variety of situations by a

variety of people.

– The model created depends on the reason for

modelling.

• Two main perspectives for creating

models are:

– IS perspective.

– Business or enterprise perspective.


16

Why model? – IS Perspective

• To design and develop IT applications.– Analyse scenarios and user needs for requirements specifications.

• A model is more abstract and often cheaper than a program.

• A model provides input to the programming process:– Requirements

– Conceptual overview of the application.

– Identify modules that can be bought or developed – decision making.

– Division of the work according to the capabilities of the application to be developed.

– Automation of the development process – Model-driven development.


17 Why model? – Business or Enterprise Perspective

• Analyse and understand a situation:– How is a situation perceived by the organisation?– Obtain an overview of the organisation:

• Organisational structure.• Functions and responsibilities.

• Links IT to organisation:– IT support for the various organisational functions.– Design IT to serve organisations.

• Link Business Strategy to IT Strategy.• Develop IT strategy for the organisation.• Identify problems and loopholes.• Design new business processes.


18

Business Strategy and ISBusiness objectives sets IT priorities!


IT

Business requirements

Organisational Processes,Innovative products & services

Requirements specifications

Design & Implement

Deploy

Drives the investment in

that delivers

In response

to

Enterprise Perspective

IS Perspective

19

Purpose of the Model

• Before creating a model, it is important to understand the

purpose of modelling and the purpose that would be

served by the model that is created. This determines:

– The design and focus of the model.

– The perspectives of the model.

– The modelling language and approach selected.

– The modelling application.

– The presentation of the model to the users.


20

Learning Goals revisited

• Different modelling perspectives, analyses of situations, Enterprise Modelling.

• This course aims to build on IS modelling from an IT perspective and examine the use of IT from an enterprise perspective.

• Thus, we will examine other kinds of models, whose primary purpose is not to design or specify IT systems; rather identify the need for IT systems and the types of systems.

• We will look at different types of models that can be created.


21

Scope of the course• Different perspectives of modelling.• Different kinds of modelling

– IS modelling: requirements, goals, actors

– Process Modelling

– Product Modelling

– Active Knowledge Modelling

– Enterprise Modelling

– Enterprise Architectures

• We will use practical examples of models.• We will look at how the different types of models relate to

one another to create Enterprise Models and Enterprise Architectures.


22

A Historical Perspective on Conceptual Modelling

(Based on an article and presentation by Janis Bubenko jr.,

Royal Institute of Technology, Sweden.

June 2005)

Pensum:

A01: Janis A. Bubenko jr: From Information Algebra to Enterprise Modelling and Ontologies – a Historical Perspective on Modelling for Information Systems in Conceptual Modelling in Information Systems Engineering. Krogstie, John; Opdahl, Andreas Lothe;

Brinkkemper, Sjaak (Eds.)


23

Conceptual Modelling

• Definition:– represents 'concepts' (entities) and relationships between them.

• May be used for enterprise models, problem analysis requirements and design specification.

• Primarily diagrammatic (2-dimensional diagrams). • The languages used for modeling have a limited vocabulary.• The languages used are originally meant to be generally applicable

(and not for a specific domain). Some exception e.g. using so-called domain specific modeling techniques.


PERSON PAPERW RITES

LANGUAGE

TITLE

N M

24

Focus of early attemps

• What were modelled were data and operations on the data.

• There was a focus on representing the domain in strict, formal, computer-independent terms.

• Data were modelled using abstract concepts.


25

Modelling during four+ decades


Pioneering work concepts

Refinement, models and extensions

The search for a common framework

Participation and understanding

-Extended scope- Standardisation efforts

60s

70s

80s

90s

2005

26







60s

70s

80s

90s

2005Database Models


Young & Kent, 1958,CODASYL, 1963,Langefors 1965

27

Young and Kent (1958)“Abstract Formulation of Data Processing Problems”


•… a way of designing different alternative implementations

•Information set/item•Defining relationship•Producing relationship•Conditions•Temporal aspects

28

CODASYL Development Committee:An Information Algebra (1962)

The goal of this work is to arrive at a proper structure for a machine-independent problem-defining language at the systems level of data processing.

… It should help the information processing community to clarify, understand the fundamental and essential features of data processing considerations.

…With current programming languages the problem definition is buried in the rigid structure of an algorithmic statement of the solution, and such a statement cannot readily be manipulated.


Source: CACM, Vol.5, No. 4, April 1962, pp. 190 - 204

CODASYL: Conference on Data System Languages

29 The Scandinavian School: Langefors

• the infological realm: where data processing problems were expressed.

• the datalogical realm: design and analysis of a information processing system.

• the “elementary message” – the smallest element that could certain any meaning.


e = <s, a, v, t>

s system point a attribute v value t time

e = <s, a, v, t>

s system point a attribute v value t time

30







60s

70s

80s

90s

2005Database Models


ANSI/X3/SPARC,IFIP Working groups

Information System Models

31

The period 1970-80 ”refinement and extensions"

• The 1975 ANSI/X3/SPARC (Standards Planning and Requirements Committee) report: the three schema approach– External– Conceptual– Internal

• IFIP WG 2.6 series: "Modelling in Database Management Systems” (1974)

• IFIP TC 8 on Information Systems (1976)


32

ANSI/X3/SPARC, 1975

• The three-schema approach offers three types of schemas with schema techniques based on formal language descriptions:– External schema for user views

– Conceptual schema integrates external schemata

– Internal schema that defines physical storage structures


User view

Computer view

Neutral view

• The framework attempted to permit multiple data models to be used for external schemata.

33

IFIP Working Groups


• IFIP: International Federation for Information Processing, an umbrella organisation for national societies working in the field of information technology.

• IFIP WG 2.6 series: "Modelling in Database Management Systems” (1974).

• IFIP TC 8 on Information Systems (1976).

34







60s

70s

80s

90s

2005Database Models


Temporal aspects,Semantic Modelling


Business rule modelling

35

Ambitions of the 80’s

• To understand better and improve parts of existing methods and tools.

• To harmonise different notions and methods.

• To enhance the requirements capture and validation stage of the

systems life-cycle.

• To provide computerised assistance to the process of developing a

specification.

• To pay attention to human, cognitive, linguistic and social aspects of IS.


36

Modelling research in the 80’s

• Improving the expressive power of semantic data models (including

abstraction mechanisms) and adding the temporal dimension.

• ”semantic modelling” vs relational data modelling.

• What are we modelling? The DB? The IS? The real world?

• The operational vs. the deductive and temporal approach.


37







60s

70s

80s

90s

2005Database Models



Modelling of ”why”, Enterprise Models


User education and participation,User focus,Organisational change

38 Modelling in the 90’s: focus on organisational aspects, participation, and understanding

… "the understanding and support of i) Human activities at all levels in an organisation.ii) Change, be it of the product, of the process or of the

organisation.iii)Complex user organisations, and individual users"

(ESPRIT 91)


39

The 90’s: Widening the scope

• Interoperable systems• Semantic heterogeneity• Non-functional requirements• Business modelling/engineering• Modelling of intentions and actors• Participative modelling• ”Method knowledge”*• ”Patterns”


40







60s

70s

80s

90s

2005Database Models





Domain specific ”ontological models” and languages

Formality vs. informal

41

Temporal aspects,Semantic Modelling







60s

70s

80s

90s

2005Database Models





User education and participation

Domain specific ”ontological models” and languages

Formality vs. informal

Young & Kent, 1958,CODASYL, 1963,Langefors 1965

ANSI/X3/SPARC,IFIP Working groups

42

Current Trends

• Enterprise Models• Active Knowledge Models• Model-Driven Development• Semantics, Ontologies• Interoperability and Standardisation• Leveraging on developments in other fields, e.g.

– AI – reasoning about knowledge, knowledge representation, uncertain knowledge

– Modelling work in other engineering fields


43

Main elements of a modelling activity


Persons

M eans forrepresentation

Area of in terest

Tools

M odelingtask

G oal o fM odelling

44

Enterprise Modelling

• The purpose of modelling is not only IS design.• Models not only address “what?”, but also “why?”.• Integrates conceptual and process models of the business

with objectives, actors, business rules and information system requirements.

• Provides traceability from information system solutions to business objectives.

• Improves the quality of modelling and the models by making it a “participatory” activity.


45

Summary

• Introduction to the course and practical information

• Historical perspective of IS modelling over 4+ decades.


46

Next Lecture

• Monday, 17 January, 12:15 – 13:00hrs,

room MA21 (Realfagbygg)

• Topic: Why model? The Role of Models in organisations.

Introduction to Modelling, using an example that illustrates the roles a

model could play in an organisation and the value of it.


Documents

TDT4252 Modelling of Information Systems Advanced Course