 may need infor- mation about the user account or his/her credit card transactions. All these services need to communicate and understand each other in order to provide a certain application with specific tasks. Businesses/operators that purchase this type of service are expecting to realize benefits along the lines of shorter payback periods, higher return on investment (ROI) and a freeing of staff to manage projects they deem more strategic to the competitiveness of their business. The basic architecture model includes web services technologies capable of: Exchanging messages/requests Describing the web services Publishing and finding web service descriptions Appendix 1: Web Services and a Service-Oriented Architecture Application End user Applications service layer Service provider Service: Service: Service: services authentication billing services Other Services Database services bank account Credit card services Credit card Credit card service other services Figure A1.2 An application that is composed from different sources Most web service applications will, most likely, be built on new or existing web tech- nologies, including HTTP, XML, SOAP, SSL, WSDL, and UDDI. (See glossary). SOAP (Simple object access protocol) allows a program running in one kind of operating system to communicate with a program in the same or another kind of an operating system (e.g. Linux Vs Windows) by using HTTP and XML as the mechanisms for information exchange. In effect SOAP is a platform-independent access protocol. The request for a web service is sent to an HTTP server. There are different methods to translate the information carried by HTTP (over TCP/IP) to XML protocol. A service-oriented architecture may have impact on network design and QoS. the end user requests a service the main issue is to analyse the required capabilities and choose proper process handling based on a viable architecture. Choice of appropriate service enablers is part of such process handling. The 'software as a service' concept offers advantages an