Page 265 - Software and Systems Requirements Engineering in Practice

ç ç 3 O F T W A R E ç ç 3 Y S T E M S ç 2 E Q U I R E M E N T S ç % N G I N E E R I N G ç ) N ç 0 R A C T I C E

OF NODE TYPES OPTIMIZED FOR SIMULATION SOLUTIONS ! PLATFORM NODE ON
THE 5-, DEPLOYMENT DIAGRAM MODEL IS ASSOCIATED WITH A NODE TYPE
THAT HAS ALREADY BEEN IMPLEMENTED BY AN EXPERT PERFORMANCE
ENGINEER
5SING THE 5-, MODELS THAT WERE GENERATED BY THE REQUIREMENTS
ENGINEERS TO SPECIFY COMPLEX ACTIVITY DIAGRAMS HAS THE POTENTIAL OF
GENERATING PERFORMANCE MODELS THAT ARE NOT OPTIMIZED FOR SOLUTIONS
BECAUSE THE PERSPECTIVES OF THE REQUIREMENTS ENGINEER AND THE
PERFORMANCE ENGINEER ARE SIGNIFICANTLY DIFFERENT 7HILE THE
REQUIREMENTS ENGINEER FOCUSES ON ELICITING AS MUCH DETAIL AS REQUIRED
TO CORRECTLY SPECIFY A CERTAIN SYSTEM FEATURE THE FOCUS OF THE
PERFORMANCE ENGINEER IS ON MODELING THE BOTTLENECK RESOURCES TO AN
EFFICIENT SOLUTION OF THE PERFORMANCE MODEL 7E RECOMMEND THAT
REQUIREMENTS ENGINEERS FOCUS THEIR EFFORTS ON DEVELOPING GOOD
SEQUENCE DIAGRAMS BY UNDERSTANDING THE APPLICATION S BEHAVIOR
WHILE PERFORMANCE ENGINEERS FOCUS ON UNDERSTANDING THE BEST WAY TO
MODEL THE NODES ON WHICH THE APPLICATION EXECUTES 4HUS PERFORMANCE
ENGINEERS DEVELOP LIBRARIES OF NODE TYPES 3OFTWARE ARCHITECTS COULD
USE THE LIBRARY OF NODE TYPES WHEN DEVELOPING THE DEPLOYMENT
DIAGRAMS TO MAKE A MAPPING BETWEEN THE SOFTWARE COMPONENTS USED
IN THE SEQUENCE DIAGRAM MODEL AND THE NODE TYPES
!CTIVITY DIAGRAMS ARE USED TO COMPLETELY SPECIFY SYSTEM BEHAVIOR
AT THE 5-, MODEL LEVEL 4HE 5-, ACTIVITY DIAGRAM MODELING
APPROACH WAS DESIGNED TO BE USED BY REQUIREMENTS ENGINEERS AND IS
WELL SUITED TO REQUIREMENTS ENGINEERING WORK (OWEVER FOR LARGE
INDUSTRIAL SYSTEMS ACTIVITY DIAGRAMnBASED MODEL SPECIFICATIONS MAY
NOT BE WELL SUITED TO BE APPLIED TO THE MODEL TRANSFORMATIONS THAT
SHOULD RESULT IN AN EFFICIENT SIMULATION MODEL &OR EXAMPLE WHILE WE
HAVE ENCOUNTERED LIMITATIONS TO MODEL THE BEHAVIOR OF DYNAMIC LOAD
BALANCING ALGORITHMS USING 5-, ACTIVITY DIAGRAM MODELS WE COULD
EASILY MODEL THESE ALGORITHMS USING THE FOLLOWING APPROACH
#ONSTRUCT A LIBRARY OF NODE TYPES
$EFINE THE GOALS OF THE ANALYSIS AND DEVELOP A SET OF USE CASES
TO DESCRIBE THE MESSAGE FLOW
$EVELOP THE DEPLOYMENT DIAGRAMS AND SELECT THE APPROPRIATE
NODE TYPES
'ENERATE THE PERFORMANCE MODEL
%VALUATE THE RESULTS OBTAINED FROM THE PERFORMANCE MODEL TO
ANALYZE IF THE REQUIREMENTS OF THE SYSTEM ARE MET

õ 2ULESõOFõ4HUMB "ESTõ0RACTICES
)N OUR EXPERIENCE WE FOUND SEVERAL ADVANTAGES OF USING USE CASE
MODELS AS THE BASIS FOR MODEL BASED SYSTEM TESTING