Modeling for Web Services Composition System with Restricted Resources

The Web services composition system usually has restricted resources in many practical applications. The system performance is closely related to the system resource. Firstly, a basic generalized stochastic Petri net model, constructed via service composition plan or language mapping for the purpose of performance presented. Nevertheless, the basic model can not reflect the characteristics of system resource restriction exactly. Therefore, through analyzing the various resource restrictions in Web services composition system, a series of extended modeling rules and methods are presented in order to acquire exact performance analysis results. The experiments indicate the difference of performance analysis results between basic model in ideal situation and extended model with restricted resources.

1. Introduction

In the researches on the Web services composition, the modeling method for the Web services composition system has been paid special attention in recent years [1]. Many theories and approaches have been applied to the modeling of Web services composition system, including FSP (Finite State Process) [2], Pi-calculus [3], AI plan [4], Petri Nets [5], etc. But most of them concentrate on model mapping and formally verifying Web services composition based on corresponding model, scarcely deal with how to facilitate the performance analysis through modeling in the preconditions of exactly reflecting the system characteristics of resource restriction.