1. “The UML Collaboration, a Standard for Role Modeling.”
OMG Technical Committee Meeting
Oslo, June 2000
Trygve Reenskaug, Mogul Norway AS, Oslo
The UML Collaboration for Role Modeling

2. Legal Notice This presentation is copyright
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Legal Notice
This presentation is copyright
©2000 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.
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

3. Activity network planning Our main example
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Activity network planning Our main example
The (toy) sample user interface is a Java Applet that is run from a web browser. The interface interacts with a background service that is also written in Java.
The top bars in the bar chart shows the earliest times when the activities can be performed. The bottom bars show when the activities all have to be done by the same resource, and this resource can only serve one activity at the time.
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

4. The Idea: Records --> Objects Some relevant shipyard objects
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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.
Object representing
a ship's part
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

5. Essential questions answered by the Collaboration
What is the purpose ?
What are the objects ?
What are their responsibilities ?
How are they interconnected ?
How do they interact ?
The UML Collaboration for Role Modeling

6. We use objects to master complexity
Object B
Object A
Message
triggers method
causes response
Port
toB
TO-B IN
Message
TO-C
toC IN
TO-C
toC
Message
Object C
Methods
Variables
Methods
Variables IN
Methods
Variables
The UML Collaboration for Role Modeling

7. First collaboration model IFIP Conference, Toronto, 1977
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First collaboration model IFIP Conference, Toronto, 1977
Saturday, December 29, 2018
/ Accounting
/ Materials
Procurement
/ Project
Group
Leader
/ Sector
/ Head of
Department 1 *
Accounting
Materials
Procurement
Head of
Department
Sector
Leader
Project
Group
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

8. The OMG vision: A Universe of objects
The UML Collaboration for Role Modeling

9. CORBA Controls the Interfaces
IDL : messages
XML : information
The UML Collaboration for Role Modeling

10. A system is a chosen perspective on reality
A system is a part of the real world which we choose to regard as a whole,
separated from the rest of the world during some period of consideration.
A whole that we choose to consider as a collection of parts,
each part being characterized by attributes and by actions which may involve itself and other parts.
Holbæk_Hanssen et.al.: System Description and the Delta Language
Oslo, 1977
The UML Collaboration for Role Modeling

11. Consider the Universe as a Universe of objects
The UML Collaboration for Role Modeling

12. The example Activity Network Objects and Interaction
fL(t) =
public void
frontLoad (int time )
Project
1:fL(0)
9:fL(19)
Activity-B
7 (4) 10
Activity-D
14 (3) 16
4:fL(10)
2:fL(6)
7:fL(16)
Activity-A
1 (6) 6
Activity-F
18 (2) 19
5:fL(13)
3:fL(6)
Activity-C
7 (7) 13
Activity-E
14 (4) 17
8:fL(17)
6:fL(13)
The UML Collaboration for Role Modeling

13. Specification level collaboration ClassifierRole definition
A ClassifierRole is a named slot for an object participating in a Collaboration.
Object behavior is represented by its participation in the overall behavior of the Collaboration.
Object identity is preserved through this constraint:
"In an instance of a collaboration, each ClassifierRole maps onto at most one object."
The UML Collaboration for Role Modeling

14. Collaborations specify system behavior
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Collaborations specify system behavior
1: fL(t1)
2: fL(t2)
/F-Pred
/F-Act
/F-Succ * *
Network frontloading collaboration 1 *
/ R-Res
/ R-Act
Resource allocation collaboration
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. 1:
alloc() 2:
reserv()
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

15. Specialization of Collaboration Frontloading with resources
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Specialization of Collaboration Frontloading with resources
/ F-Pred
/ F-Act
/ F-Succ
1: fL(t1)
2: fL(t2) * * *
/ C-Pred
/ C-Act
/ C-Succ
Synthesized model
1: fL(t1)
2: fL(t2) 1 *
/ C-Res
/ C-Act
1.1: alloc()
1.2: reserv() 1 *
/ R-Res
/ R-Act 2:
reserv() 1:
alloc()
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.
The UML Collaboration for Role Modeling
©2000 Trygve Reenskaug

16. Where we are going Lay a course to intercept the future
Vast Complexity
Transparent & Comprehensible
Participatory & Graduated knowledge
Support Human Communication
Multiple Owners
Interoperability
Geographic Distribution
Heterogeneous Platforms
The UML Collaboration for Role Modeling

17. Existing technology Lay a course to intercept the future
CORBA
Interoperability
Geographic Distribution
Heterogeneous Platforms & Languages
UML Collaboration & System Thinking
Vast Complexity
Transparent & Comprehensible
Participatory & Graduated knowledge
Multiple Owners
The UML Collaboration for Role Modeling

18. Make IT so simple that even a programmer can understand IT
Edsger Dijkstra, “A Discipline of Programming”, 1976:
Testing can only show the presence of bugs
Testing can never show the absence of bugs
The only way to avoid bugs is not to put them in in the first place
So: The number of bugs in the system when you deliver it is proportional to the number of bugs found during testing
bugs removed from Windows2000 during testing
The UML Collaboration for Role Modeling

19. What is a Component ? Object pluggable on a backplane
Objects
Collaboration links
Backplane (Container)
Net
Hardware
Operating System
Thanks to Øystein Myhre for this illustration
The UML Collaboration for Role Modeling

20. Make IT simple so that Programmers and Users can master it
Focus on:
Objects !
Responsibilities !
Message paths !
Interfaces !
Collaborations !
Invisible:
Code
Communication
etc.
Challenge: Manage complexity Solution: Collaborations & Systems
The UML Collaboration for Role Modeling

21. Thank You
The UML Collaboration for Role Modeling