The history of computing has seen several interesting trends. From a programmer building custom packaged applications to the development of Enterprise Resource Planning (ERP) systems, and other business specific packages. The need for integrating different systems in the organization led to point to point interface and spaghetti architecture. Fallout of these spaghetti architectures is the development of the Enterprise Application Integration (EAI) concept. In this paper we are going to discuss the evolution of EAI concepts and a new architecture for event driven data transformation for application integration using Web Services. The new architecture overcomes the drawback of request-reply semantics of web services by providing an event driven architecture, which supports asynchronous communication between applications using web services. We have also implemented a secure framework for accessing third party web services using message level encryption and digital certificates.