Research On Modeling,conflicts And Contacts Of Web Composition Services Based Quality Coloured Petri Nets

As one kind of new distributed computing pattern, Web composition services have provided nimble designs and development patterns for softwares development. At present, Web composition service research has aroused attention of domestic and foreign researchers .The Web composition service quality and the Web composition service checking are important research contents.However, Function checking models and quality models of Web composition services by proposed are mutually independent,which causes that the sole model dissatisfy the function and the quality analysis demands. Repetitious modelling will cause analysis time and cost inevitably increase greatly.Therefore, A formalized model is urgently needed studyand design, which model can reflect the Web composition services quality and support the model checking.This paper mainly research Web composition services modelling and checking. We mostly research to model dynamic quality of Web services and quality attribute expansion of Petri nets.This paper propose approaches to model Web composition services, to analyse quality of Web composition services, to check contacts and conflicts.The primary coverage is as follows:(1)This paper defined the concept of web services and the concept of web composition services based on qualities. This paper defined a QoS model which can describe dynamic properties of Web services quality. We analyze the insufficiency of service quality models.From the accuracy and the usability, we proposed expansion dynamic attribute quality model of Web services.This model can describe dynamic time and price attributes of Web services.This model may support to analyze Web composition services which have dynamic quality attributes describe and model.(2)This paper research to extend Petri nets. We analyze the insufficiency of time Petri nets and price Petri nets. Based on the dynamic QoS model, this paper defined a Quality Coloured Petri Net (QCPN) which is a coloured Petri net extended with quality information. This paper gives the semantics for quality coloured Petri net in terms of quality timed transition systems and argue that time Petri net is a subclass of QCPN. A cumulate price state class was defined, and this definition soundness and this definition completeness were discussed.(3)An approach is proposed to analysis composition services quality based on Quality Coloured Petri Nets. Based on the quality coloured Petri net, Transform rules are provided to formalize polymorphism Web services control structures and multi-Agents composition services. The approach availability was verified by an example analysis. The results show that applying quality coloured Petri net to model and analyze composition services is feasible.(4)An approach is proposed to check Web composition services resources conflicts. Because time constraint is imported, then time Petri net model's enabling and triggering semantics are more complex than Petri net model's, the conflict checking is more difficult. An approach is proposed to check resources conflicts of time Petri net based on time and resources constrain. Delay intervals of transitions are defined when transitions are durative enabling, and this definition soundness and this definition completeness are discussed. This paper analysises confict and disconfict states and gives an approach to compute conflict time intervals and triggering probabilities. The approach availability is verified by an example analysis. The results show that applying this approach to check resources conflicts is feasible.(5)An approach is proposed to check and resolve contacts of Web composition services. Beacause Web composition services capacities are the finiteness; this will cause that the operation of compositon services compete for capacities to bring out conflicts. This paper provides an approach to check contacts.Contacts intervals time of transitions are defined.We indicate that the current contacts resolution approach will bring dead transitions by an example. A contacts resolution approach based on changing transition time constraints is defined and proved. The approach availability is verified by an example analysis. The results show that applying our approach to check the resources contacts is correct.