Context-aware systems are concerned with identifying the context of a user and then to either provide that information based on queries or to automatically decide on appropriate actions to be taken. Some context aspects (such as location) are easy to sense through hardware, while the activity of a user has shown to be somewhat elusive to being sensed with hardware sensors. As users use web services more frequently they are exchanging messages with the services through the SOAP protocol. SOAP messages contain data, which is valuable if gathered and interpreted right - especially as this data can be shedding information on the activity of a user that goes beyond "sitting at the computer and typing". We have developed software sensors, essentially based on monitoring SOAP messages and inserting data for further reasoning and querying into a semantic context model. In this paper we consider a solution to map the data from a SOAP message to our OWL ontology model automatically. Specifically, we explain the methodology to map from SOAP messages to an existing structure of knowledge.