Raman Kazhamiakin http://dit.unitn.it/~raman/ 其导师为Marco Pistore University of Trento
Dissertation: Formal Analysis of Web Service Compositions
Raman Kazhamiakin, Paritosh K. Pandya, Marco Pistore. "Timed Modelling and Analysis in Web Service Compositions". The 1st International Conference on Availability, Reliability and Security (ARES'06), April 2006. (context-based service composition)
Raman Kazhamiakin, Paritosh K. Pandya, Marco Pistore. "Representation, Verification, and Computation of Timed Properties in Web Service Compositions". The 4th International Conference on Web Services (ICWS'06), Sep 2006. (context-based service composition)
Timed Modelling and Analysis in Web Service Compositions
要求：服务组合既要满足本身时间约束还要满足全局时间约束
Indeed,in many scenarios we expect that a Web service composition satisfies some global timing constraints, and these constraints can be satisfied only if all the services participating to the composition are committed to respect their own local timing constraints.
方法：1、 把BPEL服务组合的时间行为建模成Web Services Timed Transition Systems (WSTTS)
In this paper, we define the formalism of Web Services Timed Transition Systems (WSTTS), which extends STS to allow for modelling the timed behavior of a BPEL composition.
2、使用 duration calculus logic建模复杂的时间约束要求
We also demonstrate how the duration calculus logic can be applied for the modelling of complex timed requirements in the domain.
Analogously, transitions are annotated with the set of guards and resets. The former represent simple conditions over clocks, and the latter are used to reset values of certain clocks to zero.
In the implementationwe adopt a discrete model of time, and use a discrete-time variant of the Duration Calculus, based on (a subset of) Quantified Discrete-time Duration Calculus (QDDC, [12]), to express complex time requirements (an analysis based on a dense model of time under certain conditions may be implemented in a similar way).
服务的时间模型：
In order to model timed behavior of the compositions, we adapt the formalism of timed automata for capturing the aspects specific to the Web service domain. For these reasons, the service model is equipped with a set of special variables, namely clock variables. The values of these variables synchronously increase with the passing of time.
Let X be a set of clock variables. The syntax of time constraints 2 T
on the clock values has the form true | c t | 1 ^ 2, where the operator
is one of {,<, 6=,=,,>}, and c is an element of a domain of time
values T. A reset r 2 Y has the form (x := 0), that is the value of clock x
is set to zero.
