In order to formally reason and verify web services composition described by web services choreography specification WS-CDL,a typed formal model named typed Abstract WS-CDL（web services choreography description langu...In order to formally reason and verify web services composition described by web services choreography specification WS-CDL,a typed formal model named typed Abstract WS-CDL（web services choreography description language）for WS-CDL specifications is proposed.In typed Abstract WS-CDL,the syntax of type and session,typing rules and operational semantics are formalized;the collaborations of web services are formally described by sessions;the operational semantics of a session can help to formally reason the execution of the choreography;the typing rules can help to formally check the data type consistency of exchanged information between web services and capture run-time errors due to type mismatches.Particularly,the concepts of type assumption set extension and type assumption set compatibility are proposed,and the merging algorithm of type assumption sets is defined so as to eliminate type assumption conflict.Based on the formal model,typed mapping rules for mapping web services choreography to orchestration is also defined.With the typed mapping rules,orchestration stubs and their type assumption sets can be generated from a given choreography; thus, web services composition can be verified at choreography and orchestration levels,respectively.The model is proved to have properties of type safety,and how the model can help to reason and verify web services composition is illustrated through a case study.展开更多
Web services are provided as reusable software components in the services-oriented architecture.More complicated composite services can be combined from these components to satisfy the user requirements represented as...Web services are provided as reusable software components in the services-oriented architecture.More complicated composite services can be combined from these components to satisfy the user requirements represented as a workflow with specified Quality of Service(QoS)limitations.The workflow consists of tasks where many services can be considered for each task.Searching for optimal services combination and optimizing the overall QoS limitations is a Non-deterministic Polynomial(NP)-hard problem.This work focuses on the Web Service Composition(WSC)problem and proposes a new service composition algorithm based on the micro-bats behavior while hunting the prey.The proposed algorithm determines the optimal combination of the web services to satisfy the complex user needs.It also addresses the Bat Algorithm(BA)shortcomings,such as the tradeoff among exploration and exploitation searching mechanisms,local optima,and convergence rate.The proposed enhancement includes a developed cooperative and adaptive population initialization mechanism.An elitist mechanism is utilized to address the BA convergence rate.The tradeoff between exploration and exploitation is handled through a neighborhood search mechanism.Several benchmark datasets are selected to evaluate the proposed bat algorithm’s performance.The simulation results are estimated using the average fitness value,the standard deviation of the fitness value,and an average of the execution time and compared with four bat-inspired algorithms.It is observed from the simulation results that introduced enhancement obtains significant results.展开更多
基金The National Natural Science Foundation of China(No.60403027,60773191,70771043)the National High Technology Research and Development Program of China(863 Program)(No.2007AA01Z403)
文摘In order to formally reason and verify web services composition described by web services choreography specification WS-CDL,a typed formal model named typed Abstract WS-CDL（web services choreography description language）for WS-CDL specifications is proposed.In typed Abstract WS-CDL,the syntax of type and session,typing rules and operational semantics are formalized;the collaborations of web services are formally described by sessions;the operational semantics of a session can help to formally reason the execution of the choreography;the typing rules can help to formally check the data type consistency of exchanged information between web services and capture run-time errors due to type mismatches.Particularly,the concepts of type assumption set extension and type assumption set compatibility are proposed,and the merging algorithm of type assumption sets is defined so as to eliminate type assumption conflict.Based on the formal model,typed mapping rules for mapping web services choreography to orchestration is also defined.With the typed mapping rules,orchestration stubs and their type assumption sets can be generated from a given choreography; thus, web services composition can be verified at choreography and orchestration levels,respectively.The model is proved to have properties of type safety,and how the model can help to reason and verify web services composition is illustrated through a case study.
基金The author extend their appreciation to Deputyship for research&Innovation,Ministry of Education in Saudi Arabia for funding this research work through the Project Number(IF-PSAU-2022/01/19619).
文摘Web services are provided as reusable software components in the services-oriented architecture.More complicated composite services can be combined from these components to satisfy the user requirements represented as a workflow with specified Quality of Service(QoS)limitations.The workflow consists of tasks where many services can be considered for each task.Searching for optimal services combination and optimizing the overall QoS limitations is a Non-deterministic Polynomial(NP)-hard problem.This work focuses on the Web Service Composition(WSC)problem and proposes a new service composition algorithm based on the micro-bats behavior while hunting the prey.The proposed algorithm determines the optimal combination of the web services to satisfy the complex user needs.It also addresses the Bat Algorithm(BA)shortcomings,such as the tradeoff among exploration and exploitation searching mechanisms,local optima,and convergence rate.The proposed enhancement includes a developed cooperative and adaptive population initialization mechanism.An elitist mechanism is utilized to address the BA convergence rate.The tradeoff between exploration and exploitation is handled through a neighborhood search mechanism.Several benchmark datasets are selected to evaluate the proposed bat algorithm’s performance.The simulation results are estimated using the average fitness value,the standard deviation of the fitness value,and an average of the execution time and compared with four bat-inspired algorithms.It is observed from the simulation results that introduced enhancement obtains significant results.
