Distribuerte Systemer
Viktigere enn vi tror,
vanskeligere enn det høres
Komponenttorget ‘99
Trondheim
Trygve Reenskaug
Numerica Taskon
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:33:25 AM. Slide 1
Personal Information Environments
Content and Communication
Digital
Map
Census
Data
Police
Records
House
Drawings
Police
Dispatcher
Distaribuerte Systemer
© Trygve Reenskaug 1999
Aerial
Photos
5/29/2016 3:33:28 AM. Slide 2
The Real Challenges
The
Connected
Organization
Business
processes
Distaribuerte Systemer
Effective,
Enjoyable
and
Instructive
Tools
Task / Use Case / Tool
© Trygve Reenskaug 1999
Effective
Partitioning
of
Information
Services
Information services
5/29/2016 3:33:30 AM. Slide 3
Presentation plan
• Communication-centered architectures
A new system generation
• The Collaboration
• Remote Method Invocation (+ CORBA, COM)
• The Component (+ Java Bean, Java Enterprise Bean)
• Summary and Conclusion
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:33:31 AM. Slide 4
CPU-Centered
paradigm
Output
Input
Central
Processing
Unit
FORTRAN
Algol 60
Tape
Software
Hardware
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:33:31 AM. Slide 5
Storage-Centered
paradigm
Input
App.1
Output
Shared
database
Central
Processing
Unit
Memory
App.3
Tape
Disk
App.4
DB Schema language
e.g. Entity-Relation
e.g. NIAM
Software
Hardware
Distaribuerte Systemer
App.2
© Trygve Reenskaug 1999
5/29/2016 3:33:31 AM. Slide 6
Communication-Centered
Output
Tape
Central
Processing
Unit
Disk
Object 3
Object 2
Object 4
Memory
Hardware
Distaribuerte Systemer
Object 1
Information Bus
Input
Communication Bus
paradigm
Composition language
e.g. ????
Software
© Trygve Reenskaug 1999
5/29/2016 3:33:46 AM. Slide 7
Summary - 1
• Unlimited Scaling
• Distributed Ownership
• Support people’s Tasks
• Flexible Consistency Requirements
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:00 AM. Slide 8
Presentation plan
• Communication-centered architectures
A new system generation
• The Collaboration
• Remote Method Invocation (+ CORBA, COM)
• The Component (+ Java Bean, Java Enterprise Bean)
• Summary and Conclusion
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:01 AM. Slide 9
No Main Program!
The SYSTEM
Centralized solutions
The designer
• sees everything
• knows everything
• understands everything
• controls everything
Distributed solutions
The object
- has responsibility
- knows its collaborators
- is robust
Nobody knows everything!
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:01 AM. Slide 10
Network with Default Resource
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:01 AM. Slide 11
Network with Gantry Resource
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:01 AM. Slide 12
The objects
and their message paths
WEB Browser
Button
paint();
Code is invisible!
Applet
ActivityGraph
Project
BarChart
Project
activity-B
activity-D
activity-A
Activity-F
activity-C
Distaribuerte Systemer
© Trygve Reenskaug 1999
activity-E
5/29/2016 3:34:02 AM. Slide 13
Summary - 2
Distributed solutions
The object
+ has responsibility
+ knows its collaborators
+ is robust
Nobody knows everything!
• Move from closed to open systems
• Move from centralized to distributed control
• Change focus from build-time to run-time aspects
• Abstraction: The role the object plays in
collaboration context
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:03 AM. Slide 14
Presentation plan
• Communication-centered architectures
A new system generation
• The Collaboration
• Remote Method Invocation (+ CORBA, COM)
• The Component (+ Java Bean, Java Enterprise Bean)
• Summary and Conclusion
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:08 AM. Slide 15
Java RMI
Remote Method Invocation
WEB Browser
Client
Button
ActivityGraph
Server
App
BarChart
Project
activity-B
activity-D
activity-A
Activity-F
activity-C
activity-E
Remote access is slow and error prone.
Simplify and clarify!!!
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:11 AM. Slide 16
RMI middleware
Client
The
BarChart
object
The
ActivityGraph
object
Project Stub
represents
the Project
Activity Stub
represents
an Activity
Information Bus
(1 second can grow to 3 hours!!)
Server
The
Project
object
(A Server)
An
Activity
object
(A server)
Project
skeleton
represents
sender
Activity
skeleton
represents
sender
Java Naming & RMI Services (or CORBA or COM)
HTML - web page language
TCP/IP - Guaranteed end-to-end data stream
Physical communication (ISDN/Ethernet/….)
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:12 AM. Slide 17
Presentation plan
• Communication-centered architectures
A new system generation
• The Collaboration
• Remote Method Invocation (+ CORBA, COM)
• The Component (+ Java Bean, Java Enterprise Bean)
• Summary and Conclusion
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:12 AM. Slide 18
Why use components
Use componets to
• Simplify
remote communication
• Avoid coding
to save time
• Avoid coding
to increase quality
• Use tools
to increase your productivity
• Get transactions, security, etc.
for free
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:12 AM. Slide 19
What is a Component
• Tools are used to compose systems
• A component is reused by cloning
• A Component is an object playing
standardized roles
• A Component is a reusable object
Technology
•
•
•
•
•
System user
Organization
System composer
Component creator
Tool developer and vendor
Component environment standardizer
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:13 AM. Slide 20
Compose User Interface
with Java Beans
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 21
Bean object plays
several roles
Composer
Use Case
Run-time
display
Use Case
BeanBox
App
Bean Object
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 22
Java Bean
• User Interface
• Properties
• Events
• Composition
• Run time context
Information Bus
Component standardization
examples
Enterprise Java Bean
• Naming
• Persistence
• Transactions
• Security
• Load sharing
Client
Distaribuerte Systemer
Server
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 23
Presentation plan
• Communication-centered architectures
A new system generation
• The Collaboration
• Remote Method Invocation (+ CORBA, COM)
• The Component (+ Java Bean, Java Enterprise Bean)
• Summary and Conclusion
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 24
Distributed Systems
What you get:
• Unlimited scaling
• Distributed ownership
• Specific task support
• Information partitioning
How you do it:
• Think in terms of objects, their responsibilities
and collaboration.
• Think in terms of open systems, no main
program.
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 25
Component-based development
What you get:
• Build by composing library objects,
avoid coding.
• Leverage infrastructure mechanisms
(transactions, security, persistence,…)
How you do it:
• Think in terms of objects.
(Responsibilities, environment, collaboration.)
• Penetrate vendor fog - find essentials
• Insist on high product quality
• Adapt to new layers in value chain
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 26
The competing technologies
CORBA™ Object Management Group (OMG)
Public standards
Java™
SUN Microsystems
Build once, run anywhere
COM™
Microsoft
Dominating on desktops
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 27
Distributed systems
You can do it!
http://www.ifi.uio.no/~trygve
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 28
Distaribuerte Systemer
© Trygve Reenskaug 1999
5/29/2016 3:34:15 AM. Slide 29