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back to the incomingmessageās originator. This pinpoints interoperability at the site of
the callee process. The observation coins the essence that interoperability on the con-
solidation level ismore thancommunicationbecause it demandsadependencebetween
message reception andmessage emission. This dependence is the result of some oper-
ation beyond syntacticmessage parsing.As consequence, it enables us to discriminate
betweenamessage-dependentbehavior andanarbitrarybehavior.
4.3. CausalModeling
Our observation of themessage passing behavior of interoperable processes from sec-
tion 4.2 establishes a cause-effect relation.We formulate this behavior as a structural
causalmodel (SCM)whichdescribes in a functional formhow the components interact
witheachother.Asaresult,wehaveclear rules foranalyzing interoperableprocesses.A
structural causalmodeldeļ¬nedbyPearl[15] is anordered triple<U,V,F>with
ā¢ U, a setof exogenousvariableswhicharenotdeterminedby themodel
ā¢ V, a setof endogenousvariableswhicharedeterminedby themodel
ā¢ E, set of structural equations toexpress thevaluesofvariables inV
Wedeļ¬ne theendogenousandexogenousvariables in table1for theSCMof interopera-
bleprocesses.Foreachvariable in table1weneed todeļ¬ne itsvalueusing thestructural
Component EndogenousVariablesV ExogenousVariablesU
Incomingmessage M UM
Dispatcher P UP
Outgoingmessage Mā² UMā²
Discriminator D UD
Table1. Causalmodelvariabledeļ¬nition
equations fM, fP, fMā², fDāE. These equations relate the variableswith each other and
conclude themodel.
MessageM. TheincomingmessageMconsistsofanoperationspeciļ¬cationandcorre-
spondingarguments.Theoperationop is takenfromsetFM ofoperations.WespecifyM
usingEBNF.
M :=op, {Arg}
op :=op1 |op2 | ... |opk
, where Arg=UM are the arguments of the operation op unknown to the model and
opāFMwith |FM|=k.
DispatcherP. The dispatcher parsesM andmaps the operation speciļ¬edwithin to a
local operation from the set FP which are accessible by the dispatcher on the callee
process. If thedispatchercannotļ¬nd theoperationspeciļ¬ed in the incomingmessage, it
returnsanunknownresult.
P := fP(M,UP)
:= {
op , ifopāFPā©M
UP , otherwise
S. Kotstein and C. Decker /AnApproach for Measuring IoT Interoperability 175
Intelligent Environments 2019
Workshop Proceedings of the 15th International Conference on Intelligent Environments
- Title
- Intelligent Environments 2019
- Subtitle
- Workshop Proceedings of the 15th International Conference on Intelligent Environments
- Authors
- AndrƩs MuƱoz
- Sofia Ouhbi
- Wolfgang Minker
- Loubna Echabbi
- Miguel Navarro-CĆa
- Publisher
- IOS Press BV
- Date
- 2019
- Language
- German
- License
- CC BY-NC 4.0
- ISBN
- 978-1-61499-983-6
- Size
- 16.0 x 24.0 cm
- Pages
- 416
- Category
- TagungsbƤnde