Service-oriented architecture has emerged as a major software development paradigm. It helps in developing web applications to run on heterogeneous and distributed platforms. However, the basic building blocks of such applications, known as web services, are loosely coupled entities, which are dynamically discovered. In fact, web services are described, published, advertised, discovered and invoked over the Internet. Due to this dynamism, the future behavior cannot be foreseen. A failure or downtime of one web service could cause the failure of a complete application. Therefore, it is important to monitor web services during all activities so that an anomalous situation can be detected as soon as it occurs. This paper presents the monitoring solutions implemented during various phases of a web service’s life cycle.

Since the advent of Service-Oriented Architecture (SOA) (Papazoglou et al., 2007), web services have become one of the major research challenges. Web services are modular, self-contained, self-describing, distributed services providing interoperatability for different software applications to run on different platforms. They can be described, published, advertised, located and invoked over the World Wide Web, as shown in Figure 1.

Web services can be deployed on multiple hosts having different operating systems, using different languages and built for various enterprises (Papazoglou et al., 2005), which make it difficult to measure, control and manage various functional and nonfunctional requirements. Though functional requirements play a vital role in web services, non-functional requirements are given equal weightage as well. While choosing among different web services available over the Internet, Quality of Service

Information Technology Journal, Web service requirements, Service specification, Selection, Composition, Discovery, Recovery, Service-Oriented Architecture (SOA), Quality of Service.