AbstractServices are combined and then controlled via an orchestration engine to achieve a business process. These services can be internal to the organization or COTS, which raises the question of authentication of the quality of services. The problem SOA developers currently face is the lack of a system to guarantee a third-party service. A service provider may provide complaints regarding a service, but these complaints must be validated. Even the service provider may not have any idea that their service has degraded over time due to increased traffic, data, or some other elements. Each consumer has their own expectations from the service and different criteria are set as standards for the acceptability of a service. This article contains the research conducted on the impact of a third-party service on a composite service and a model has been proposed to test these services. INTRODUCTION Web services constitute an important part of the Internet in today's IT-driven economy. The Web service is an interface that describes a set of operations accessible remotely via standardized XML messaging [17]. These services offer functionality ranging from simple math functions to more complex web-based banking applications. Different companies have adopted web services technology and started providing services through the web to their customers. Companies strive to provide the best possible service to their customers by introducing new innovations in their services. Latest innovations in the field of web services include the concept of service-oriented architecture and composite services. Service Oriented Architecture provides the principles that make...... middle of paper ......s", International Workshop on Systems Development in SOA Environments (SDSOA'07) 0-7695-2960-7 /07 © 2007 IEEEAnton Michlmayr, Florian Rosenberg, Christian Platzer, Martin Treiber and Schahram Dustdar, “Toward Recovery from the Broken SOA Triangle – A Software Engineering Perspective,” IW -SOSWE '07, September 3, 2007, Dubrovnik, Croatia Copyright 2007 ACM ISBN 978-1-59593-723-0/07/09Matthias Galster, Eva Bucherer, “A Taxonomy for Identifying and Specifying Nonfunctional Requirements in Service-Oriented Applications Development,” 2008 IEEE Services Conference 2008 - Part I. .978-0-7695-3286-8/08 2008 IEEE.Valeria Cardellini, Emiliano Casalicchio, Vincenzo Grassi, Raffaela Mirandola, “A test model for optimal service selection in broker-based architectures with multiple QoS classes », Proceedings of the IEEE Services Computer Workshops (SCW'06) 0-7695-2681-0/06 2006 IEEE.