This thesis provides an overview of Web Services technology. The concept of Web Services and Service Oriented Architecture are explained. The thesis focuses on the mechanisms for transporting and addressing messages in web services, especially SOAP. It presents the development history of SOAP, an overview of the SOAP 1.2 specification, and the differences between SOAP in version 1.1 and 1.2. Further, the thesis presents two web servers for development and deployment of web services using Java and .NET technology, i.e. Bea Weblogic Server 9.2 and Internet Information Services 7.0. The web server implementations are evaluated both in terms of conformance to the SOAP specifications as well as their performance (response time and throughput). The results showed that the servers performed very similar both for SOAP 1.2 and SOAP 1.1 messages. The response times and throughput are similar for both servers in most cases. There are, however, situations when Weblogic perform significantly worse than IIS, and when IIS is noticeable worse than Weblogic. The thesis presents also general security aspects of sending messages.