Architecture Modeling - SPES 2020
Architecture Modeling - SPES 2020
Architecture Modeling - SPES 2020
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6.1.1.1.2<br />
Properrty<br />
Definition<br />
Some ppatterns<br />
alloww<br />
slightly different<br />
interrpretations<br />
of o their beha avior. This ccan<br />
be cont trolled by<br />
attributess<br />
that are apppended<br />
to th he pattern.<br />
6.1.1.1.2.1<br />
Iterattive<br />
vs. Flowing<br />
Obbservation<br />
[D.2.4.5] ] Patterns, in<br />
general, express e reactive<br />
behavior<br />
of the fo orm: "triggerring<br />
behavio or implies<br />
promisedd<br />
behavior" wwhich<br />
means:<br />
wheneverr<br />
the triggerin ng behavior is identified at some tim me instant<br />
or intervval,<br />
the prommised<br />
behavio or will occur r at some tim me instant or r interval righht<br />
now or in bounded<br />
future.<br />
wheneveer<br />
car-reqquest<br />
occu urs car-arrrives<br />
oc ccurs during<br />
[0min, 3min]<br />
For instaance,<br />
in the aabove<br />
instantiated<br />
patterrn<br />
"car-reque est" is the trig ggering behaavior,<br />
and "ca ar-arrives<br />
within 3mmin"<br />
is the ppromised<br />
be ehavior. An ooccurrence-in<br />
nstance of th he behavior of a reactiv ve pattern<br />
refers too<br />
the duratioon<br />
that starts s with an ideentification<br />
of o the triggering<br />
behavioor<br />
and ends with the<br />
followingg<br />
occurrencee<br />
of the promised<br />
behavioor.<br />
A patternn<br />
can be useed<br />
in two manners,<br />
depennding<br />
on the evaluation of o its occurreence-instance<br />
es:<br />
<br />
<br />
Pattern.<br />
In the "iterattive"<br />
manner r only iterativve<br />
occurrenc ce-instances s of the behaavior<br />
are considered,<br />
nnamely:<br />
nextt<br />
identificatio on of triggerinng<br />
behavior does not sta art before thee<br />
end of the promised<br />
bbehavior<br />
of previous instance<br />
(hencee,<br />
a triggerin ng behavior that occurs wwhile<br />
an occ currence-<br />
iinstance<br />
takees<br />
place is ig gnored).<br />
In the “flowinng”<br />
manner, every occurrrence-instanc<br />
ce of the beh havior is conssidered.<br />
In practicce,<br />
most of tthe<br />
patterns‟ ‟ usage is off<br />
the iterative e manner. Flowing<br />
interppretation<br />
is significant s<br />
only when<br />
there is one-to-one matching between<br />
occu urrences of the triggerinng<br />
behavior and the<br />
promisedd<br />
behavior; ffor<br />
instance, when the prromised<br />
behavior<br />
is expe ected to occuur<br />
fixed dura ation after<br />
the triggeering<br />
behavior.<br />
There arre<br />
two kinds of flowing in nterpretation.<br />
For both ki inds (both kinds<br />
are speecified<br />
by the e attribute<br />
flowing) a new instannce<br />
of the pa attern becommes<br />
active fo or each occurrence<br />
of thee<br />
trigger and d requires<br />
an action<br />
in the inteerval.<br />
In the standard caase<br />
one occ currence of the t action caan<br />
terminate e multiple<br />
active instances<br />
of thhe<br />
same pattern.<br />
If the aadditional<br />
attr ribute “once” is specified,<br />
for each oc ccurrence<br />
of the triggger<br />
exactly one occurre ence of the action<br />
in the interval<br />
is req quired.<br />
Examplees<br />
of standarrd<br />
and “once”<br />
specificatioon<br />
of a flowin ng pattern:<br />
whenever<br />
whenever<br />
Attribute es: attribb1,<br />
attrib b2.<br />
a occurs<br />
a occurs<br />
<strong>Architecture</strong> <strong>Modeling</strong><br />
b occurs<br />
b occurs<br />
during [e e,f]. Attr ribute: fllowing.<br />
during [e e,f]. Attr ribute: fllowing,<br />
once.<br />
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