Vol.3 No.3 2010
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Research paper : A methodology for improving reliability of complex systems (A. Katoh et al.)−202−Synthesiology - English edition Vol.3 No.3 (2010) among components are modeled according to the expression form of the model checking tool to be applied. Also, formulae are developed from the properties which must be satisfied by the cooperative behavior, based on the expression form of the model checking tool. The developed models and the formulae are input to the model checking tool. If counterexamples are output from the model checking tool, the counterexamples are analyzed and the inconsistency of the cooperative behavior is fed back to architectural designing. Based on the inconsistency of the cooperative behavior which is fed back, architectural designing is done according to the workflows of this methodology. If no counterexamples are output from the model checking tool, the component specifications and the interface specifications among components whose cooperative behavior is consistent are released, and they are output as results of this methodology.4.2 Bridge methodIn the methodology of this research, system verification is conducted for the cooperative behavior by components in the system design phase. It is necessary to connect the outputs of architectural designing to the inputs of model checking seamlessly. We develop the method to derive the specifications related to the cooperative behavior, the properties which must be satisfied by the cooperative behavior, and the model checking tool to be applied, based on the component specifications, the interface specifications among components, the traceability matrix, and the system specification. This is called bridge method because it serves as the bridge between architectural design method and model checking. Bridge method is novel since it focuses on the cooperative behavior to present a specific means for synthesizing the systems engineering standard such as IEEE 1220 and model checking. Figure 8 shows the bridge method for architectural design method and model checking. Figure 8 corresponds to the details of the bridge method shown in the central part of Fig. 6. The inputs of the bridge method include the component specifications, the interface specifications among components, the traceability matrix, and the system specification.First, specifications related to the cooperative behavior are extracted from the component specifications and interface specifications among components. Figure 9 shows specifications related to the cooperative behavior in the component specifications and interface specifications among components. The traceability matrix is used when specifications related to the cooperative behavior by the component specifications are extracted. If the system specification corresponds to multiple component specifications in the traceability matrix, a function of the system is achieved when these components cooperate. In the case of Fig. 7, the 5.1 function XA of the component A specification and the 5.1 function XB of the component B specification cooperate to achieve the 4.1 function X of the system specification. In Fig. 9, this corresponds to the striped part of the component A specification and the component B specification. The specifications related to the cooperative behavior in interface specifications among components are extracted based on interface information within the component specification related to the cooperative behavior. In Fig. 9, this corresponds to the part of the message in the center.Next, the properties which must be satisfied by the cooperative behavior of the components are extracted from the system specification based on the traceability matrix. The reason is that it is necessary for the cooperative behavior by the components extracted by the traceability matrix to satisfy the system specification achieved by the cooperative behavior. In case of Fig. 7, the cooperative behavior of the 5.1 function XA of the component A specification and the 5.1 function XB of the component B specification must satisfy the properties of the 4.1 function X of the system specification.BridgemethodAttributesSelection of Model checkingtoolIdentificationof attributesExtraction of properties to be satisfiedExtraction ofcooperativebehaviorSystemspecificationTraceabilitymatrixComponentBspecificationInterfacespecificationbetweencomponentsComponentAspecificationComponentAspecificationforcooperativebehaviorComponentBspecificationforcooperativebehaviorInterfacespecificationfor cooperativebehaviorProperties tobe satisfiedModelchecking toolFig. 8 Bridge method for architectural design method and Model checkingFig. 9 Specifications related to cooperative behaviorSpecification related to cooperative behaviorProcessingMessageComponentspecificationrelated tocooperativebehaviorComponent BspecificationComponentAComponent AspecificationInterface specificationrelated to cooperativebehaviorComponentBComponentspecificationrelated tocooperativebehavior

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