Web Service is a method used by electronic devices to communicate with one another over a network. It is a software feature constantly available at a network address over the Web. These are the web-based applications which are self-controlled, self-descriptive, module-oriented programs that can be distributed, found, and used online. The Web services carry out a wide range of tasks from straightforward requests to intricate business procedures. When they are employed, other software programs and web services can find them and use them from any location and at any time.
The World Wide Web Consortium (W3C) has provided the definitions and web standards for web services. W3C has defined web services as, the software component that is designed to support machine-to-machine interoperability, and interactive as well over a network.
Quality can be functional or non-functional attributes of web services. If quality is measured according to functionality, then quality is functional attribute otherwise non- functional. The quality that signifies non-functional parameters like total time taken for service to accomplish, the cost of invoking, availability, security features, execution time, etc. The quality attributes of a web services are mainly related to four domains.
There may be several vendors of web services, therefore finding and selecting the best and easily accessible web service is a tedious task. The finding and selection, allow organizations to form alliances to provide better services and make available all the things at a single point for the customers.
There are numerous services available on the cloud, but every service has restricted use. A single provider is no longer adequate to fulfil the entire user's requests; therefore, the regular services must be combined through service composition to perform a particular task. Hence, the thought of composite services is beginning to be utilized as an assortment of services combined to accomplish a client's request. All in all, from a client's point of view, this composition keeps on being considered to accomplish the task, even though the composition is made from a set of web services
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It is the central issue that needs to be addressed during the communication of web services. Threats like message alteration, loss of confidentiality, denial of services, authorization, and man-in-the-middle attacks may affect webservices security.
The performance of web service applications depends on service delivery strategies. Performance can be analyzed the perspective of the service user and the service process. Service providers are essentially considered to provide some elementary qualities of services. The elementary requirements, in this case, are speed, readiness, security, and reliability.
