A UTP semantic model for Orc language with execution status and fault handling

• Published in: Frontiers of Computer Science Vol. 8; no. 5; pp. 709 - 725
• Main Authors: LI, Qin, ZHAO, Yongxin, ZHU, Huibiao, HE, Jifeng
• Format: Journal Article
• Language: English
• Published: Heidelberg Higher Education Press 01.10.2014; Springer Nature B.V
• Subjects: Applications programs; Computer Science; Concurrency; denotational semantics; Failure; operational semantics; Orc language; Research Article; Semantics; service oriented computing; unifying theories of programming; UTP; Web services; Web应用程序; 故障处理; 状态信息; 语义模型; 语言; 错误处理程序; 面向服务; Orc language; unifying theories of programming; service oriented computing; operational semantics; denotational semantics
• ISSN: 2095-2228; 2095-2236
• DOI: 10.1007/s11704-014-3385-2

The Orc language is a concurrency calculus proposed 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 semantics for Orc does not contain the execution status of services so that a program cannot determine whether a service has terminated normally or halted with a failure after it published some results. It means that this kind of failure cannot be captured by the fault handler. Furthermore, such a semantic 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 contains execution status information. A failure handling semantics 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 better than one without. An extended operational semantics is also proposed and proven to be equivalent to the denotational semantics.