The Orc language is a concurrency calculus pro- posed to study the orchestration patterns in service oriented computing. Its special features, such as high concurrency and asynchronism make it a brilliant subject for ...The Orc language is a concurrency calculus pro- posed to study the orchestration patterns in service oriented computing. Its special features, such as high concurrency and asynchronism make it a brilliant subject for studying web applications that rely on web services. The conventional se- mantics for Orc does not contain the execution status of ser- vices so that a program cannot determine whether a service has terminated normally or halted with a failure after it pub- lished some results. It means that this kind of failure cannot be captured by the fault handler. Furthermore, such a seman- tic model cannot establish an order saying that a program is better if it fails less often. This paper employs UTP methods to propose a denotational semantic model for Orc that con- rains execution status information. A failure handling seman- tics is defined to recover a failure execution back to normal. A refinement order is defined to compare two systems based on their execution failures. Based on this order, a system that introduces a failure recovery mechanism is considered bet- ter than one without. An extended operational semantics is also proposed and proven to be equivalent to the denotational semantics.展开更多
基金This work was supported by the National High Tech- nology Research and Development Program of China （2012AA011205）, the National Natural Science Foundation of China （Grant Nos. 61361136002, 61321064 and 91118007）, Shanghai Knowledge Service Platform Project （ZF1213） and Shanghai Minhang Talent Project.
文摘The Orc language is a concurrency calculus pro- posed to study the orchestration patterns in service oriented computing. Its special features, such as high concurrency and asynchronism make it a brilliant subject for studying web applications that rely on web services. The conventional se- mantics for Orc does not contain the execution status of ser- vices so that a program cannot determine whether a service has terminated normally or halted with a failure after it pub- lished some results. It means that this kind of failure cannot be captured by the fault handler. Furthermore, such a seman- tic model cannot establish an order saying that a program is better if it fails less often. This paper employs UTP methods to propose a denotational semantic model for Orc that con- rains execution status information. A failure handling seman- tics is defined to recover a failure execution back to normal. A refinement order is defined to compare two systems based on their execution failures. Based on this order, a system that introduces a failure recovery mechanism is considered bet- ter than one without. An extended operational semantics is also proposed and proven to be equivalent to the denotational semantics.
