1. OO-NIK 2002
4/16/2017 4:19 AM
Objektorientering og Informasjonssystemer for det 21. århundre (Understand – Explore – Master – Control)
NIK 2003
Oslo. 25 november 2003
Trygve Reenskaug
IfI, UiO
OO-NIK 2003
©2002 Trygve Reenskaug

2. Legal Notice This presentation is copyright
OO-NIK 2002
Legal Notice
4/16/2017 4:19 AM
This presentation is copyright
©2003 Trygve Reenskaug Oslo, Norway.
All rights reserved.
Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that the copies are not made for profit or commercial advantage and that copies bear this notice and full citation on the first page.
OO-NIK 2003
©2002 Trygve Reenskaug

3. The Invention of Object Orientation
OO-NIK 2002
The Invention of Object Orientation
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Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

4. Simula… A system description language
SIMULA BEGIN:
By a system we mean a collection of components which are either
acting upon other components,
being acted upon,
or mutually interacting…"
OO-NIK 2003

5. SIMULA BEGIN fig. 1.1.2 A I I I I A MODEL SYSTEM PERSON LANGUAGE
SYSTEM DESCRIPTION
I: Information transfer
A: Actions
OO-NIK 2003

6. SIMULA BEGIN (1973) Example: A Post Office System
COUNTER
POST OFFICE
DOOR
COUNTER
CLERK
QUEUE
CUSTOMER
LIST OF
TASKS
CARRY OUT ALL TASKS
CUSTOMER
CARRY OUT ALL TASKS
LIST OF TASKS
CUSTOMER
CARRY OUT ALL TASKS
LIST OF TASKS
OO-NIK 2003

7. The small, but significant, difference Procedure Oriented
[ Brad Cox 87]
activityA duration... start…
end...
norm_ frontload
(…)
activityB weight...duration... start…
end...
Planner Client
activityC weight...duration... start…
end...
crane_ frontload
(…)
activityF duration... start…
end...
OO-NIK 2003

8. The small, but significant, difference Object Oriented
[ Brad Cox 87]
activityA duration... start…
end...
frontload
(…)
activityB weight...duration... start…
end...
Planner Client
frontload
(…)
frontload(time)
activityC weight...duration... start…
end...
activityF duration... start…
end...
OO-NIK 2003

9. Two Approaches to Object Orientation
"East Coast Approach": Object orientation is a smart programming artifact. An object is an instance of a class.
"West Coast Approach": Object Orientation is a powerful tool for thinking. An object is an entity with a well-defined boundary and identity that encapsulates state and behavior without revealing its interior construction.
OO-NIK 2003

10. The Clerk metaphor for Object Orientation
Object B
Object A
Message
triggers method
causes response
Port
TO-B
toB IN
Message
TO-C
toC IN
TO-C
toC
Message
Object C
Methods
Data
Methods
Data IN
State
Behavior
Identity
Encapsulation
Polymorphism
Communication (Collaboration)
Inheritance
Methods
Data
OO-NIK 2003

11. The Idea: Records --> Objects Some relevant shipyard objects
OO-NIK 2002
4/16/2017 4:19 AM
Object representing
the Shipyard
Object representing a ship’s schedule
Object representing
the shipyard resources
Object representing
a construction activity
Object representing
a resource
Our example is taken from a shipyard. We represent important aspects by objects and let work scheduling be performed through negotiation between these objects.
Fikk ikke til…
persistens
typing, lack of encapsulation.
Object representing
a ship's part
OO-NIK 2003
©2002 Trygve Reenskaug

12. IS21c-Information Systems for the 21st Century
OO-NIK 2002
Smalltalk
4/16/2017 4:19 AM
Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

13. Alan Kay's Dynabook Owner can view, navigate, edit objects
OO-NIK 2002
Alan Kay's Dynabook Owner can view, navigate, edit objects
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OO-NIK 2003
©2002 Trygve Reenskaug

14. Smalltalk Personal Information Environment
OO-NIK 2002
Smalltalk Personal Information Environment
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Klassesett, world's first personal computer
OO-NIK 2003
©2002 Trygve Reenskaug

15. Smalltalk-78 in Oslo with Else Nordhagen
OO-NIK 2002
Smalltalk-78 in Oslo with Else Nordhagen
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OO-NIK 2003
©2002 Trygve Reenskaug

16. IS21c-Information Systems for the 21st Century
OO-NIK 2002
Objective C, C++ , Java
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Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

17. Role Modeling / OOram Activity Objects
OO-NIK 2002
Role Modeling / OOram Activity Objects
4/16/2017 4:19 AM
Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

18. The original 1979 MVC The TOOL AS A COMPOSITE
Mental Model
Computer Model
Editor
View
Controller
User
OO-NIK 2003

19. IS21c-Information Systems for the 21st Century
OO-NIK 2002
UML 1.x
4/16/2017 4:19 AM
Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

20. Java class definition: Activity
OO-NIK 2002
Java class definition: Activity
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public class Activity {
protected String name; protected int duration; protected int earlyStart = 0; protected int counter = 0; private Activity[] successors; … … …
public void frontLoad (int time) { earlyStart = Math.max (earlyStart, time); if ((counter += 1) >= predecessors.length) { int fin = getEarlyFinish(); for (int i=0; i<successors.length; i++) { successors[i].frontLoad(fin+1); } } } … … … }
public class Activity {
protected String name;
protected int duration;
protected int earlyStart;
protected int counter = 0; private Activity[] successors;
… … …
public void frontLoad (int time ) {
earlyStart = Math.max (earlyStart, time);
if ((counter += 1) >= predecessors.length) {
int fin = getEarlyFinish();
for (int i=0; i<successors.length; i++) {
successors[i].frontLoad(fin+1); }
OO-NIK 2003
©2002 Trygve Reenskaug

21. Activity UML class model
OO-NIK 2002
Activity UML class model
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Activity
successors
int duration;
int earlyStart;
int counter; *
void frontLoad (int time);
int getEarlyFinish(); *
OO-NIK 2003
©2002 Trygve Reenskaug

22. Activity UML class hierarchy model
OO-NIK 2002
Activity UML class hierarchy model
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Activity
duration: int
earlyStart: int
counter: int
NormalActivity
resource: NormalResource
/ getEarlyFinish(): int
frontLoad (int time): void
getEarlyFinish(): int
CraneActivity
resource: CraneResource
load: int
/ getEarlyFinish(): int
0..*
0..*
successors
Inheritance overrated:
Too large surface area
Cannot change superclasses,
Delegation/components better, give better control.
OO-NIK 2003
©2002 Trygve Reenskaug

23. The essence of frontloading Communication
OO-NIK 2002
The essence of frontloading Communication
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Pred
Act
Succ
1: fL(t1)
2: fL(t2) *
We change our perspective from classes to objects; from sets to individuals. This permits us to study patterns of interacting objects: What are the objects, what are their responsibilities, and how do their collaborate to achieve the system functionality.
The role represents the object’s position in the structure. We see that instances of the Activity class play different roles: Predecessor, Activity, and Successor. Instances of the Project class are also Predecessors, in this way a Project can start the frontloading operation. The Project also plays the Successor role so that it can receive the final scheduling messages.
We achieve a separation of concern; a collaboration describes the objects involved in one or more functions, describing the objects involved only and focusing on the relevant object properties.
OO-NIK 2003
©2002 Trygve Reenskaug

24. The essence of frontloading Communication Diagram
OO-NIK 2002
The essence of frontloading Communication Diagram
4/16/2017 4:19 AM
Pred
Act
Succ
1: fL(t1)
2: fL(t2) *
We change our perspective from classes to objects; from sets to individuals. This permits us to study patterns of interacting objects: What are the objects, what are their responsibilities, and how do their collaborate to achieve the system functionality.
The role represents the object’s position in the structure. We see that instances of the Activity class play different roles: Predecessor, Activity, and Successor. Instances of the Project class are also Predecessors, in this way a Project can start the frontloading operation. The Project also plays the Successor role so that it can receive the final scheduling messages.
We achieve a separation of concern; a collaboration describes the objects involved in one or more functions, describing the objects involved only and focusing on the relevant object properties.
OO-NIK 2003
©2002 Trygve Reenskaug

25. Specialization of Collaboration Frontloading with resources
OO-NIK 2002
Specialization of Collaboration Frontloading with resources
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1: fL(t1)
2: fL(t2)
Pred
Act
/ Activity
Succ * * 1
1.1: alloc()
1.2: reserv() *
We change our perspective from classes to objects; from sets to individuals. This permits us to study patterns of interacting objects: What are the objects, what are their responsibilities, and how do their collaborate to achieve the system functionality.
The role represents the object’s position in the structure. We see that instances of the Activity class play different roles: Predecessor, Activity, and Successor. Instances of the Project class are also Predecessors, in this way a Project can start the frontloading operation. The Project also plays the Successor role so that it can receive the final scheduling messages.
We achieve a separation of concern; a collaboration describes the objects involved in one or more functions, describing the objects involved only and focusing on the relevant object properties.
Res
OO-NIK 2003
©2002 Trygve Reenskaug

26. Interfaces in the Basic scheduling collaboration
OO-NIK 2002
Interfaces in the Basic scheduling collaboration
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The interfaces specify minimal requirements
to receiving objects
Pred
fL(t1)
Act
fL(t2)
Succ
«Interface»
FrontloadIntf
frontLoad(t)
We change our perspective from classes to objects; from sets to individuals. This permits us to study patterns of interacting objects: What are the objects, what are their responsibilities, and how do their collaborate to achieve the system functionality.
The role represents the object’s position in the structure. We see that instances of the Activity class play different roles: Predecessor, Activity, and Successor. Instances of the Project class are also Predecessors, in this way a Project can start the frontloading operation. The Project also plays the Successor role so that it can receive the final scheduling messages.
We achieve a separation of concern; a collaboration describes the objects involved in one or more functions, describing the objects involved only and focusing on the relevant object properties.
OO-NIK 2003
©2002 Trygve Reenskaug

27. UML 2.0 (Now being finalized)
OO-NIK 2002
UML 2.0 (Now being finalized)
4/16/2017 4:19 AM
Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

28. UML 2.0 Proposal: Components, Parts, Ports, Links
From partners' presentation to OMG Nov 2001 (With permission)
OO-NIK 2003

29. ? UML 3.0 ? An Executing System Environment
OO-NIK 2002
? UML 3.0 ? An Executing System Environment
4/16/2017 4:19 AM
Objects Simula I
Multi Process C
Algol-60
Augment
Lisp
E-R
Simula 67
Smalltalk
Role Modeling
C++
UML 1.x
Squeak
Java
UML 2.0
IS21c-Information Systems for the 21st Century
OO-NIK 2003
©2002 Trygve Reenskaug

30. We create system models to master our environment
OO-NIK 2002
We create system models to master our environment
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User's model of the application
utility - cause and effect
Architect's model of the running system
objects - containment - roles - responsibilities
behavior - interactions - state machines - actions
Coder's model of the code
classes - features - inheritance - packages - deployment
User's model of the application
utility - cause and effect
Architect's model of the running system
objects - containment - roles - responsibilities
behavior - interactions - state machines - actions
Coder's model of the code
classes - features - inheritance - packages - deployment
OO-NIK 2003
©2002 Trygve Reenskaug

31. OO-NIK 2003

32. OO-NIK 2003

33. OO-NIK 2003

34. OO-NIK 2003

35. Thank You
More info at
OO-NIK 2003

36. OO-NIK 2002
4/16/2017 4:19 AM
More details ….
Unified Modeling Language (UML). Object Management Group. Version 2.0, Final Adopted specification
Roles and artifacts in cognitive psychology: Steven Pinker: How the Mind Works. Norton, New York ISBN
The reference work on role modeling: Reenskaug, Wold, Lehne: Working With Objects. This book is out of print. A .pdf version kan be downloaded free from
The theory of role modeling: Egil P. Andersen: Conceptual Modeling of Objects. A Role Modeling Approach. Dr Scient thesis. Dept. of Informatics, University of Oslo. 4 November ftp://ftp.nr.no/pub/egil/ConceptualModelingOO.ps.gz
Richard Pawson and Robert Matthews: Naked Objects. See
OO-NIK 2003
©2002 Trygve Reenskaug