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www.wileyeurope .com/college/van lamsweerde Chap.1: Setting the Scene © 2009 John Wiley and Sons 2
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/ '&!

,
“Serve more passengers”
“Reduce transfer time among terminals”

H
/ '
/
&&-55&
!$%&.
/
!$(4&!,
4'
/ 2$%&
+
+
15
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 
© 2009 John Wiley and Sons
0!*20

G1!(($<
&
&
-&4.
/ !$%&
/
,44555

/
$$!&

,
“Computation of safe train accelerations”
“Display of useful information for passengers inside trains”

H
/ G!!
/ !$
/
$'$$%&
+
+
16
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 
© 2009 John Wiley and Sons
0!*2#

$!$%&4&4
(($
/
$!$!<$%&
/
!(&$

,
–
“Safe train acceleration”555$

(($-&.


&
+
–
“Accurate estimation of train speed/position”555$
'


+

H
/ &&!!

+
+
17
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!,

*!+
/
0!$1!!
/ 0!,!*234*20*2#
/
0&&,&
0&&,&

&5
&5
&
&
/
,
,
&
&
5
5
(
(
/ 0!,44
/
0&
/
0%
/
!
/ !!
18
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

H&
H&!
!!!$!&-&.

/
4!4
/ 55“If train doors are closed, they are not open”
“If the train’s acceleration is positive, its speed is non-null”

:&
:&$!
!!$!&-&.
55“Doors shall always remain closed when the train is moving”

G,
/ &$4'4
$&
/
&
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

!555
/
$!&
/
!$!&1!(($,


!


$!!45
Environment Software
TrainMoving
TrainAtPlatform
DoorsClosed


measuredSpeed ≠ 0
doorsState = 'closed'
errorCode = 05
trainPosition-DB
updated
TrainMoving
TrainMoving


→
→
DoorsClosed
DoorsClosed
measuredSpeed
measuredSpeed
≠
≠
0
0


→
→

doorsState = 'closed'
doorsState = 'closed'
20
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 
© 2009 John Wiley and Sons
0,

4




,
&

&
!-!.
/ $$!(($$!
!!
/
&$$$
TrainMoving
→
→ DoorsClosed


,
&


!
!
/ $$!(($
/ !&$&
measuredSpeed ≠ 0
→
→ doorsState = 'closed’
-E!&.
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0,
44

H
H,
&
$$
!-!(($.
trainAcceleration > 0
→
→ trainSpeed ≠ 0


,$$!&!
(($
/
&!
/

&-55.
measuredSpeed ≠ 0
iff
iff trainSpeed ≠ 0

H
H,&

/
!&
“measuredSpeed is the speed estimated by the train’s speedometer”
22
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© 2009 John Wiley and Sons
measuredSpeed
G,
DoorsClosed
,&$
trainSpeed
doorsState
&
,&$
#,
0F
#H& (e.g. actuators)
GH& (e.g. sensors)

⊆
⊆ 

×
× &?&$

⊆
⊆G
×
×#?&$
I

-4H4.






,
!J(&$@:BCD
23
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&&

SOFREQ, ASM, DOM |= SysReq
 8
G
G!SOFREQ, the assumptions in ASM
and the domain properties in DOM4
!

!!SysReq9
SofReq: measuredSpeed ≠ 0
→
→ doorsState = 'closed’
ASM: measuredSpeed ≠ 0
iff
iff trainSpeed ≠ 0
doorsState = 'closed’
iff
iff DoorsClosed
Dom: TrainMoving
iff
iff trainSpeed ≠ 0

SysReq: TrainMoving
→
→ DoorsClosed
!44&44
&1
24
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

,
,$what services!
(($!&
/ &4
$

/ 
“The software shall control the acceleration of all trains”

>(,
>(,how such services
should be provided
/
)
),444
?4$4555
/ #!,4!4&
/
0$(
“Acceleration commands shall be issued every 3 seconds to every
train”
25
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(
Non-Functional Requirement
Quality of Service Compliance Architectural Constraint Development Constraint
ConfidentialityIntegrity
Availability
DistributionInstallationSafety Security
Usability
PerformanceReliability
Maintainability
Cost
Time Space

Deadline
Variability
Software
interoperability
Convenience
Interface
User
interaction
Device
interaction
Subclass link
Accuracy
Cost

!$'

>($4$&
/
?(,55
(
/
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