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
目前软件应用广泛,对软件可靠性要求越来越高。近几年云计算技术的研究逐渐增多,对于云平台的可靠性技术也有了新的要求。Amazon Web Services(AWS)提供了一整套云计算服务,用户能够构建复杂、可扩展的应用程序。AWS在最小成本情况下,...目前软件应用广泛,对软件可靠性要求越来越高。近几年云计算技术的研究逐渐增多,对于云平台的可靠性技术也有了新的要求。Amazon Web Services(AWS)提供了一整套云计算服务,用户能够构建复杂、可扩展的应用程序。AWS在最小成本情况下,为用户提供了一套构建容错的软件系统平台。在技术和性能等多方面的优势,被业界广泛认可和接受。该文主要研究Amazon Web Services云平台中的核心组件是如何提供可靠性技术的,分别对核心组件Amazon EC2,Amazon Simple Storage(S3),Elastic Storage Block(EBS),Elastic Load Balancing,Auto Scaling进行研究分析,为以后云计算平台的搭建和可靠性技术的研究提供依据。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.
