There is no doubt that there is great demand for large-scale distributed applications. Indeed, tremendously expensive special-purpose distributed systems have been deployed and today are used extensively in the banking, airline, and telecommunication industries. The major barrier to supporting these, and even richer, applications on the Internet is the difficulty of designing, building, testing, and maintaining distributed applications using the tools that comprise the state-of-the-art today.

Distributed application is a program designed to run on multiple computers. To execute a business logic, you may need to talk to various software running on multiple computers on the network. If the application is divided into tires, it is a distributed application. So, if your J2ee components are deployed on separate computers, then it is a distributed application.

In this paper we have demonstrated that Web services are the base for a new era of dis-tributed computing. Web services are virtual components hiding from their users idiosyncrasies of the concrete (application server) technology chosen to implement the Web service. Especially, users can easily mix and match functions from heterogeneous environments into a single application if those functions are rendered as Web services. Based on a service oriented architecture a user does not even have to care about a particular Web service he is communicating with because the underlying infrastructure, i.e. the service bus, will make an appropriate choice on behalf of the user. This choice is based on policies of both, the user and the Web services qualifying under the user’s functional request, and the choice is also influenced by service level agreements and demand for an optimal utilization of the overall environment.