Page 286 - 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

PLACEHOLDER REPRESENTATIONS OF THE SEEMINGLY IRRELEVANT STEPS
TO ENABLE STAKEHOLDER REVIEW 4HE LEVEL OF DETAIL USED FOR
INDIVIDUAL STEPS VARIES ACCORDING TO THE STAKEHOLDERS NEED
FOR CLARIFICATION SUCH THAT THE MOST NOVEL UNCERTAIN OR RISKY
STEPS WILL BE EXPLORED MOST THOROUGHLY
v )F THE STORYBOARD DESCRIBES A NONTRIVIAL DYNAMIC BEHAVIOR IT
SHOULD BE SUMMARIZED IN THE FORM OF A BEHAVIOR MODEL -OST
STAKEHOLDERS WILL UNDERSTAND THE SEMANTICS OF SIMPLE STATE
BASED MODELS SUCH AS STATE MACHINES PARTICULARLY IF NO CYCLIC
BEHAVIORS ARE INVOLVED
v 7HEN A REQUIREMENTS ENGINEER ELABORATES A STORYBOARD
TOGETHER WITH A DOMAIN STAKEHOLDER THE FOLLOWING QUESTIONS
SHOULD BE ADDRESSED WITH RESPECT TO EACH STEP OF A
STORYBOARDED SCENARIO
v !RE ALL ALLOWED OPTIONAL INTERACTIONS ENUMERATED !RE
THEIR EFFECTS DESCRIBED
v !RE ALL DISABLED OR FORBIDDEN INTERACTIONS ENUMERATED
!RE THE REASONS CLARIFIED
v $OES THE STAKEHOLDER AGREE WITH THE ENABLED AND DISABLED
INTERACTIONS 7HY NOT
v !RE ALL THE VISUAL ITEMS PROPOSED FOR THIS SCREEN STEP
CONSISTENT WITH THE USER S NEEDS 7OULD DIFFERENT
PRESENTATIONS BE USEFUL
v !RE THERE VISUAL ITEMS THAT ARE MISSING 7HAT WOULD THE
STAKEHOLDER WANT TO SEE AND WHY
v )S THERE PROPER EMPHASIS ON THE IMPORTANT DATA ASPECTS IN
A GIVEN STEP 7HAT IS THE IMPORTANT DATA AND WHY 4HIS
LEVEL OF DISCUSSION IS MOST LIKELY TO INVOLVE 5) DESIGNERS
BUT IT IS VERY IMPORTANT FOR THE DEVELOPERS TO STAY INVOLVED
IN ORDER TO PROVIDE INPUT ON WHAT SCREEN REPRESENTATION
TECHNOLOGY CAN OR CAN T DO

%XECUTABLE 0ROTOTYPES
#ERTAIN ASPECTS OF APPLICATION BEHAVIOR CAN BE MODELED USING A
DESCRIPTIVE NOTATION AND THEN ENACTED BY AN ENGINE THAT INTERPRETS
THE MODEL 4HIS TYPE OF PROTOTYPING IS SIMILAR TO USING $ MODELING
SOFTWARE TO REPRESENT PHYSICAL MODELS &OR EXAMPLE THE PROTOTYPE
CAN GIVE AN OVERVIEW AND FLYTHROUGH CAPABILITY AND EVEN PROVIDE
SOME ANALYSIS IF THE MODEL ALLOWS IT
&ULLY EXECUTABLE PROTOTYPES ARE THE MOST GENERIC ALTERNATIVE FOR
CREATING A REALISTIC AND UNAMBIGUOUS REPRESENTATION OF SOME ASPECT
OF THE APPLICATION 4HE PRIMARY BENEFIT OF DEVELOPING EXECUTABLE
PROTOTYPES IS THAT THEY INCLUDE SOME ABILITY TO VERIFY THE SOLUTION AS
WELL AS DIRECTLY INTRODUCING REALISTIC ELEMENTS INTO THE ANALYSIS OF