Providing access to a Public Transport Schedule system for Smart Phone Clients

Abstract: This master thesis was conducted during an internship at HBT GmbH with the purpose of providing access to an existing public transport schedule system in Hamburg (Germany) for smart phone clients. A state-of-the-art literature review and an evaluation of an existing SOAP (Simple Object Access Protocol) based web service to access public transport schedule information were conducted to identify the drawbacks of the existing interface with respect to the limitations and characteristics of smart phone clients. One of the main drawbacks is that the use of SOAP based web services and the associated data exchange format XML introduces a high amount of overhead that has to be transmitted between client and server. Additionally the information that is returned from the existing SOAP web service is not adjusted to the needs of smart phone clients. Based on these drawbacks recommendations are given how to implement an interface which provides an improved access to public transport schedule information for smart phone clients. These recommendations include the identification of public transport information that is most relevant for smart phone clients as well as to use REST (Representational State Transfer) web services and the data formats JSON and Fast Infoset for the implementation. To quantify the improvements that were achieved by accessing a newly implemented REST web service in terms of transferred data volume, request-response time and serialisation/deserialisation time a performance test was conducted. Therefore a native iPhone application was developed which accesses the existing SOAP based web service and the newly implemented REST style web service. The performance test showed that the use of the implemented REST web service to access public transport information from smart phone clients leads to a significant improvement in contrast to the existing SOAP based web service.