This document discusses using model-based development approaches for large, distributed real-time systems. Such systems are often costly and late due to performance issues found late in development. The document proposes using functional models early to analyze performance before implementation. It presents an example system and shows how functional elements, processes, and performance chains can be modeled. Model-driven architecture is suggested to help trace requirements through design stages and optimize non-functional properties like performance without changing system functionality.

1. Model Based Development of
Distributed Real Time Systems
Mike Giddings
Part Time PhD Student
Part Time PhD Student
Start: October 2008
Probation not complete

2. Large Distributed
Real Time systems
Very often large distributed periodic real‐time systems are :‐
• Time consuming to develop.
• Frequently cost more than estimated
• Frequently overrun.

3. Large Distributed
Large Distributed
Real Time systems
Real Time systems
Original Performance Analysis
Fix-it-later
Fi it l t approach
h
Need to analyse performance early to avoid detecting a
performance problem at th end of th project which i
f bl t the d f the j t hi h is
expensive to rectify

4. Large Distributed
Large Distributed
Real Time systems
System features that have been studied
Client server systems
Event driven systems
Telecommunication systems
Systems with shared resources
y
Concurrent processing

5. Large Distributed
Large Distributed
Real Time systems
Process Control Systems
Open/Closed L
O /Cl d Loop systems
t
Consisting of following system elements
Processing elements, sensors, controls, displays and
communication system elements

6. Large Distributed Real
Large Distributed Real
Time Process Control systems
Example System

7. Graphical Representation of
Functional Elements

8. Functional Elements
Functional Elements
Other Functional Objects or Other Functional
Element Diagrams
El Di attributes
ib Element Diagrams
dataName11
dataName6
dataName12 ProcessB ABCD1250
dataName1 dataName7
ABCD1230 ABCD1250
dataName13
dataName8
ABCD1250
dataName2
ABCD1230
dataName3 ProcessA
ABCD1231
ABCD1231 dataName4
dataName9
dataName5 ABCD1251
ABCD1231
dataName14 dataName10
ProcessC
ABCD1251
dataName15
dataName16
Objects or
attributes One or methods which
can be represented by
can be represented by Objects or
sequence diagram attributes

9. Performance Chains

10. Iterator Operation

11. MDA PIM to PSM
Translation
(May be UML)
( )
(May be UML)

12. The Problems
The Problems
• Performance failures are discovered at the end of
development when they are expensive to resolve.
• Poor traceability between design stages.
• Difficult to analyse performance from UML diagrams.
• Design Notations
– Allow different views of the system to become disjointed.
– Are frequently to the wrong level of abstraction.
• Domain specialists require a functional overview without
which requirements will be inadequately specified.
which requirements will be inadequately specified

13. Good features
Good features
• Model real world requirements
• Understandable by domain experts
• Model Functionality
• Model User Interface
• Easy to formulate the design
• Manage non functional requirements
• Calculate/animate performance

14. Conclusions
• The use of MDA alongside functional model offers the
possibility of overcoming some of the practical difficulties
involved in the development of complex distributed iterating
systems.
• Functional Model enables performance optimisation by
changing the iteration schedules without changing the
functionality.
f i li