In this paper, Wireless Sensor Networks (WSN) and Service-Oriented Architecture (SOA) approaches are analyzed given that represent both emerging and key role for Intelligent Transportations Systems (ITS). However, It is worth noting that WSN and SOA approaches have begun to be applied into ITS separately and day by day these approaches tend to be combined to get the best outcomes for both safety and security for ITS applications. For this reason, a discussion of the principals ITS applications of these two approaches and a case study, that has been designed and implemented to illustrate their advantages, are presented. The case study is focused on support a very useful ITS service associated with the localization of parking spaces.