Dynamic Evolution Of Web Service Composition Based On Dynamic Slicing And Lazy Computing

The number of web service has increased a lot in recent years, but as the extreme increasing ofdifferent requirements, web services can’t satisfy the great number of demand from users. So webservice composition technology is proposed. However, every single web service in a compositionservice is under dynamic evolution, so web service composer needs to check the compositionservice every second and update it if the single service evolutes, which is not flexible. To make theevolution flexible, this paper proposes a dynamic evolution method for web composition service.We make web composition service can be only updated when the composition service calls thesingle web service which needs to be updated.The main work of this paper includes:(1) we analyzeBPEL of the composition service and convert it to C codes;(2) we analyze the C codes and generatefunction dependence graph;(3) According to the input value, we use dynamic slicing technology toslice the C codes to generate sliced dependence graph and the sliced codes;(4) With the help ofAxis2in Tomcat, we publish some service and compose some services, then we use an example todemonstrate the process of the dynamic evolution of web service composition.The main contributions of this paper are listed as follows:Propose and design the convertion method from BPEL to C. There are a lot of similaritiesbetween BPEL and C, so to better analyze BPEL codes, BPEL codes are converted to Ccodes and through analyzing C codes, the information of BPEL codes can be obtained.Propose and design the service dependence graph of composed web service based on thefunction dependence graph of C codes. To better analyse the denpendec relationship of thecomposed service, we analyze the C codes and generate function dependence graph.Propose and design the dynamic slicing algorithm. The execution path of the compositionservice varies from different input value. To obtain the exact execution path, we proposedynamic slicing algorithm to slice the source codes.Taking use of the properties of lazy computing, we execute the composed web service lazily.Through dynamic slicing, the exact execution path can be obtained. It can be high effectivewhen only the exact execution path is executed.