1. Unleashing the Power of Distributed Objects
EDOC ‘99 Mannheim September 1999
Trygve Reenskaug
Numerica Taskon, Oslo
Unleashing the Power of Distributed Objects

2. Legal Notice This presentation is copyright
©1999 Trygve Reenskaug Oslo, Norway.
All rights reserved.
Unauthorized reproduction prohibited.
Unleashing the Power of Distributed Objects

3. The Connected Enterprise Tools & Services
Digital
Map
Census
Data
Police
Records
House
Drawings
Aerial
Photos
Police Dispatcher
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

4. Advantages Communication-Centered paradigm
Unlimited Scaling
Distributed Information Ownership
Support people’s Tasks
Flexible Consistency Requirements
Fideikommiss hits
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

5. The Visionaries
“The visionary is the only true realist.” Federico Fellini
Einar Thorsrud, Fred Emery Sociotechnical Systems. Theory X and Y
Douglas Engelbart Computer augmentation, Collective IQ
Alan Kay The Dynabook, a personal information system
Christopher Alexander A pattern language for humane environments
Unleashing the Power of Distributed Objects

6. Theory X vs. Theory Y (MacGregor)
Dislike work
Lack ambition
Are irresponsible
Are resistant to change
Prefer to be led rather than to lead
Theory Y
Are willing to work
Are capable of self-control
Are willing to accept responsibility
Are imaginative and creative
Rigid, controlling environment
Bored, passive workers
Authoritarian leadership
Flexible, supportive environment
Interested, creative workers
Inspiring leadership
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

7. Our Challenges Organization: Effective Flexible Innovative Information
Supportive
Information
Services:
Well-defined
Coherent
Evolving
Tools:
Effective,
Enjoyable
Instructive
Personalized
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

8. CPU-Centered paradigm
Output
Input
Central
Processing
Unit
FORTRAN
Algol 60
Tape
Hardware
Software
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

9. Storage-Centered paradigm
Shared
database
App.1
App.2
App.4
App.3
DB Schema language
Entity-Relation
NIAM
Output
Input
Memory
Central
Processing
Unit
Disk
Tape
Hardware
Software
Unleashing the Power of Distributed Objects

10. Communication-Centered paradigm
Object 1
Object 2
Object 4
Object 3
Information Backplane
Central
Processing
Unit
Input
Output
Disk
Communication Backplane
Memory
Tape
Composition tools ??
UML Collaboration/OOram
Hardware
Software
Unleashing the Power of Distributed Objects

11. No Main Program! Centralized solutions The designer sees everything
knows everything
understands everything
controls everything
The SYSTEM
Distributed solutions
The object -
has responsibility
knows its collaborators
is robust
Nobody knows everything!
Unleashing the Power of Distributed Objects

12. We use objects to master the age of distribution
Object-B IN
OUT-B
OUT-C
Methods
Variables IN
OUT-C
Object-C
Methods
Variables
Object-A IN
Methods
Variables
Message
triggers method
causes response
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

13. What is a Component ? Object pluggable on a backplane
Objects
Collaboration paths
Backplane (Container)
Operating System
Net
Hardware
Thanks to Øystein Myhre for this illustration
Unleashing the Power of Distributed Objects

14. What is a Component? A Component is a (reusable) object
A Component is an object playing standardized roles within a container
A component does not know its clients
A component is reused by cloning
Tools are used to compose systems
Unleashing the Power of Distributed Objects

15. Component Value Chain Application Assembler (User expert)
Component Deployer (Production engineer)
Component Provider (Domain expert)
Component Container Provider (System programmer)
Unleashing the Power of Distributed Objects

16. Compose User Interface with Java Beans
Unleashing the Power of Distributed Objects

17. App. for booking meeting rooms
Unleashing the Power of Distributed Objects

18. Component standardization examples
Information Bus
Java Bean
User Interface
Properties
Events
Composition
Backplane
Enterprise JavaBean
Naming
Persistence
Transactions
Security
Load sharing
Backplane
Client
Server
Unleashing the Power of Distributed Objects

19. Application Assembler perspecive
WEB
Browser
Applet e.g., init(); paint(Graphics);
AppletContext e.g., getImage(URL)
RoomBooker e.g., getRooms(); reserve(...);
BookingApplet (end user tool)
Booking (business logic)
Room Chooser
Java Beans
JComboBox e.g., addItem(...); getSelectedItem();
ActionListener e.g., actionPerformed(ActionEvent)
Unleashing the Power of Distributed Objects

20. See Collaboration Hide implementation
WEB
Browser
BookingApplet (end user tool)
Room Chooser
Java Beans
Booking (business logic)
The object
has responsibility
knows its collaborators
is robust
Nobody knows everything!
Code is
invisible!
Objects References Interfaces
are visible!
Unleashing the Power of Distributed Objects

21. Component Provider perspective
Information Bus
WEB
Browser
Name
Server
Applet (End user tool)
1: lookup("roombroker");
Booking
Home
Factory object
Booking Bean
Booking
Object
2: create(xxx);
3: ejbCreate(xxx);
4: getRooms();
Room Chooser
Java Beans
5: getRooms();
6: addItem(element)
Unleashing the Power of Distributed Objects

22. Your Obstacles Pest and cholera
Windows NT
4.0 SP 3
CORBA
EJB
HTML
(XML?)
IIOP
COM - DCOM - COM+
Java (1.1.7B) (1.2)
TCP/IP
SQL
Swing
Java
RMI
ODBC
Java
Beans
JINI
JDBC
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

23. Focus on Objects ! Responsibilities ! Collaborations !
Visible:
Objects References Interfaces
Processes
Invisible:
Code
Communication
etc.
Unleashing the Power of Distributed Objects

24. Organize for large scale development !
Application Assembler Empower user
Component Deployer Limit choice & make available
Component Container Provider Provide tools and service environment
Component Provider Create capability
Unleashing the Power of Distributed Objects

25. Your Real Challenge: Solutions for humans !
Organization:
Effective
Flexible
Innovative
Supportive
Information
Services:
Well-defined
Coherent
Evolving
Tools:
Effective,
Enjoyable
Instructive
Personalized
Unleashing the Power of Distributed Objects
© Trygve Reenskaug 1999

26. Go home and do it! http://www.ifi.uio.no/~trygve Distributed systems
COLLABORATIONS
Unleashing the Power of Distributed Objects

27. Unleashing the Power of Distributed Objects