BPEL谓词约束建模及可行路径分析

Predicate Constraint Oriented BPEL Modeling and Feasible Path Analysis

为了解决由于缺乏谓词约束表达式的建模和分析带来的业务流程执行语言(business process execution language,BPEL)中路径分析不准确问题,提出了一种针对BPEL中XPath表达式的谓词约束分析和建模方法,并在此基础上提出了BPEL可行路径的分析算法.与以往BPEL建模中大多仅考虑结构化行为不同,该方法系统分析了数据封装对执行路径的影响.该方法综合考虑BPEL中表达式的语法结构以及结构化活动对BPEL中变量的影响,采用扩展行为影响的变量结构树对BPEL中原子数据表达式进行建模,并进一步考虑了复合谓词表达式的建模和基于此模型的BPEL可行路径分析方法.最后,结合案例分析了该方法的可行性.

Due to the fact that single Web service is too simple in function to accomplish complex business requirement,a coordinated aggregate method （service composition） is introduced to build enterprise solutions by combining multiple existing enterprise services.A composition of services is comparable to a traditional application in which its functional scope is usually associated with the automation of a parent business process.Based on XML,BPEL uses XPath to bind variables and define expressions.Different from WSDL which can only define simple constraint by pre-and post-condition,XPath expressions combined with structured activities provide the more expressive ability to define constraint.Both white-box testing and model checking are based on BPEL modeling and feasible path analyzing.For BPEL,only considering the structural activities and ignoring the data manipulation and constraints will bring some negative impacts.To address this issue,we propose an XPath expression oriented predicate constraint analyzing and modeling approach and introduce a feasible path analysis algorithm based on this model.This approach takes into account the data manipulation effects on the feasible path.We firstly analyze the syntax of BPEL expressions and make a normalizing to the BPEL expressions.Then,the activity effect extended variable structure tree is used to model the atomic expression and the composite predicate expression.Moreover,the feasible path analysis algorithm is discussed using the established model.Finally,by case studying,the feasibility and experiment process of our approach are illustrated.