Inversion of web service invocation using publish/subscribe push-based architecture

Abstract

Among enterprise application integration solutions, Web Service is a promising technology to achieve the interoperability in heterogeneous environments. However, traditional Web Service invocation may lead to unnecessary network traffic, long response time, and bottleneck problems at service providers. While a publish/subscribe model provides an advantage of prompt notification which can eliminate unnecessary network traffic, its achievement in interoperability is still limited. By integrating Web Service technologies with a publish/subscribe model, a pull-based provider architecture, a pull-based broker architecture, and a push-based architecture are mentioned in this dissertation. Whereas services are provided at service providers in the pull-based provider architecture, services in the pull-based broker architecture are provided at the broker. However, these two kinds of pull-based architecture use the integrated solution based on traditional Web Service invocation, still the bottleneck problems are likely to occur. Therefore, we propose an alternative, push-based architecture which presents an innovative approach of using inversion of Web Service invocation. To get data messages, service clients do not need to invoke Web Services at service providers as usual. Service providers are responsible for distributing data messages by invoking Web Services at the service clients instead. Thus, service clients simply wait for data messages from service providers without sending any requests. In the push-based architecture, a canonical message model must be used to represent the standardized format for data exchange. The canonical message comprises of a topic name and a Web Service Description Language. All publishers and subscribers of the same topic must use the same canonical message. Services at the broker and subscribers are invoked via their endpoint addresses. Experimental results showed that the total response time was significantly minimized and the bottleneck problems at service providers were eliminated in the push-based architecture. Thus, service providers of the push-based architecture can be very small and thin in ubiquitous computing such as sensor or mobile devices.