Today, the travel information services are dominantly provided by Global Distribution Systems (GDS). The Global Distribution Systems provide access to real time availability and price information for flights, hotels and car rental companies. However GDSs have legacy architectures with private networks, specialized hardware, limited speed and search capabilities. Furthermore, being legacy systems, it is very difficult to interoperate them with other systems and data sources. For these reasons, Web service technology is an ideal fit for travel information systems. However to be able to exploit Web services to their full potential, it is necessary to introduce semantics. Without describing the semantics of Web services we are looking for, it is difficult to find them in an automated way and if we cannot describe the service we have, the probability that people will find it in an automated way is low. Furthermore, to make the semantics machine processable and interoperable, we need to des...