NSPF: Designing a Notification Service Provider Framework for Web Services

Abstract

In this paper we extend current typical Web service architectures by providing a Notification Service Provider Framework (NSPF). Besides the three standard roles found in current frameworks (i.e., the service provider, the service requestor, and the service registry), our approach introduces an additional role that we call the service notifier. The framework is designed in four layers: the Proxy Layer, the Web Server Layer, the Application Notification Server Layer, and the Application Worker Layer. Since the NSPF itself is a service provider, this framework is reflective in the sense that it checks and notifies itself about changes. The framework is documented using design patterns. The set of patterns applied in the framework design includes the following patterns: the singleton, the delegation, the factory method, the observer, the mediator, the notifier, which is a combination of the mediator and the observer, the item description, and the proxy. The notifier pattern is in fact a publish-subscribe pattern with push semantics. The framework uses a requestor profile to support notifications related to a category of events related to changes, failures, and version control problems of Web services.