1. A component- and message-based architectural style for GUI software
Richard N. Taylor et al.
IEEE Transactions on Software Engineering, Vol.22, No.6, June 1996
Presented by Leonardo Salayandia
Software Architecture Class
Feb 26, 2008
CS Topics in Software Design: Software Architecture

2. CS 5381 - Topics in Software Design: Software Architecture
Overview
Introduction
The C2 architectural style
Example (KLAX)
The Argo design environment
Related work
Feb 26, 2008
CS Topics in Software Design: Software Architecture

3. CS 5381 - Topics in Software Design: Software Architecture
Introduction (1/2)
Architectural styles are key design idioms
pipe-and-filter
blackboard
Styles typically used in user interface software
Client-server style (e.g., X-Windows)
Call-back style
Model-View-Controller style
Arch style
C2 is another (C2 from Chiron-2)
“Network of concurrent components hooked together by message routing devices.”
Feb 26, 2008
CS Topics in Software Design: Software Architecture

4. CS 5381 - Topics in Software Design: Software Architecture
Introduction (2/2)
Motivation for C2 style
Support component-based software development
Extend UI code reuse beyond toolkit code
Support multi-lingual programming
Support distributed, heterogeneous environments
Support dynamic architectural changes
Others
Feb 26, 2008
CS Topics in Software Design: Software Architecture

5. The C2 architectural style (1/6)
The internal architecture of a C2 component
Receives notifications and send requests
Determines requests that can be received and notifications that can be sent
Mapping between component’s internal semantic domain and that of the connector above
react to a notification
execute a request received
maintain some constraint
Receive requests
Send notifications
Feb 26, 2008
CS Topics in Software Design: Software Architecture

6. The C2 architectural style (2/6)
Notifications and requests
Asynchronous communication via messages
Notification: Report state changes (e.g., routine that was invoked, parameters, and return value)
Request: Invoke desired functionality from another component
Send notification
Receive requests
Send requests
Receive notification
Feb 26, 2008
CS Topics in Software Design: Software Architecture

7. The C2 architectural style (3/6)
Connectors
Bind components together
Connected to components and other connectors
Routing and broadcast of messages
Message filtering
No filtering
Notification filtering
Prioritized
Message sink
Feb 26, 2008
CS Topics in Software Design: Software Architecture

8. The C2 architectural style (4/6)
Architecture composition and properties
Requests that a component accepts
one-to-one OR one-to-many
Connector domains defined in terms of domains from connected components along with connector’s filter
Pair wise relationships between connected components and connectors
Feb 26, 2008
CS Topics in Software Design: Software Architecture

9. The C2 architectural style (5/6)
Domain translation
Transformation of requests issued by a component into domain of recipient
Transformations of notifications received by a component into its domain
Simple domain translations
Message name matching
Parameter matching
May be automatically generated for some cases
Other factors in domain translation
Differences in state notified and state expected
Missing parameters
Unit conversions
Tradeoff between communication efficiency and component reusability
Feb 26, 2008
CS Topics in Software Design: Software Architecture

10. The C2 architectural style (6/6)
Principles
Substrate independence
Message-based communication
Multi-threaded
No assumption of shared address space
Multiple programming languages
Heterogeneous environments
Implementation separate from architecture
Feb 26, 2008
CS Topics in Software Design: Software Architecture

11. CS 5381 - Topics in Software Design: Software Architecture
Example
KLAXTM
Multiple implements
Single process
Multi-threaded
Multi-process
Components not changed
Multi-lingual (C++ and Ada)
Components swapped
Performance issues not noticeable
State
Game logic
Abstract graphics
Layout manager
Graphics binding
Feb 26, 2008
CS Topics in Software Design: Software Architecture

12. The Argo design environment
Graphical design environment
White rectangles represent components
Black bars represent connectors
Arcs represent pathways
Ovals in rectangles represent ports
Conceptual arch VS Implementation arch
Collaboration: design critics
Some code generation (C++)
Architecture analysis (pro-active design critics)
Feb 26, 2008
CS Topics in Software Design: Software Architecture

13. CS 5381 - Topics in Software Design: Software Architecture
Related work
Implicit invocation
Messages and message mechanisms
Layered systems
Language and process support
Component interoperability models
Design environments
Relating C2 concepts to OO types
Feb 26, 2008
CS Topics in Software Design: Software Architecture