AbstractServices are combined and then controlled via an orchestration engine to realize a business process. These services can be internal to the organization or COTS, which raises the question of authenticating the quality of services. The current problem for SOA developers is the lack of a system that guarantees third-party service. A service provider may make claims about a service, but those claims must be validated. Even the service provider may have no idea that its service has degraded over time due to increased traffic, data or other elements. Each consumer has their own expectations of the service and different criteria are set as standards for the acceptability of a service. This paper contains research conducted on the impact of a third-party service on a composite service, and a model for testing these services has been proposed. INTRODUCTION Web services have been 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 provide functionality ranging from simple mathematical functions to more complex banking applications on the web. Several companies have adopted web services technology and started providing services over the web to their customers. Companies have tried to provide the best possible service to their customers by introducing new innovations in their services. The 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, “Towards Recovering the Broken SOA Triangle – A Software Engineering Perspective,” IW -SOSWE '07, 3 September 2007, Dubrovnik, Croatia Copyright 2007 ACM ISBN 978 -1-59593-723-0/07/09Matthias Galster, Eva Bucherer, “A Taxonomy for Identifying and Specifying Non-Functional Requirements in Service-Oriented Development”, 2008 IEEE Congress on Services 2008 - Part I. 978-0-7695-3286-8/08 2008 IEEE.Valeria Cardellini, Emiliano Casalicchio, Vincenzo Grassi, Raffaela Mirandola, “A Testing 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.