Sensor network applications are executed in diverse scenarios, different platforms and in an uncontrolled environment. The data aggregation and then handling the data at the middleware demands an approach to integrate functionalities of various interests from diverse network clusters. So instead of a proprietary solution for individual problems, it is desirable to have a platform independent service oriented architecture. SOA is composed of interactive Web services called by client applications. Secured access and use of Web services is a primary requirement in these applications. From software engineering point of view, authentication and logging are the cross cutting concerns for the Web services. Instead of using conventional object oriented approach for handling concerns in every class or method, we propose use of Aspect oriented programming paradigm to reduce the code overhead of the system.