Extended Abstract: Quality of Service and Quality of Experience Networked ICT services keep on invading our private and professional lives. Increasingly many work processes depend on ICT services, which obviously define the efficiency of how tasks are solved. The perceived usability of a service is thereby heavily linked to the performance of the service, for instance its responsiveness. Users do not like to wait unnecessarily; long response times might interrupt their flow of thoughts and finally entail a loss of interest. Quality aspects seen from the user’s point of view have gained importance. Users rate the quality of the ICT services explicitly (by rating and commenting them) or implicitly (by using them happily, reluctantly or not at all). In case several alternative ICT services exist and pricing is not a primary matter of concern, quality may become the discriminating factor between different providers and might decide upon success or failure. While the rather traditional notion Quality of Service (QoS) is mostly related to technical quality parameters, the recently established notion of Quality of Experience (QoE) extends the notion of quality to include user perception. Obviously, QoE has strong subjective components and is also connected to the situation and context in which the user finds him- or herself. For instance, a certain response time of a service (e.g. providing an answer within four seconds) can be considered sufficient in a relaxed situation, but not when the user is in a stressed situation, e.g. having to make an urgent decision based on the result displayed by the service. User stress takes an impact on the threshold(s) marking off different levels of perception (excellent; good; fair; bad; etc.). More background to this particular issue is found in [2]. In the course of this work, we aim at finding quantitative relationships between the context in which the user finds him- or herself and the expectations regarding the – technical – performance in terms of QoS parameters such as the response time. Service Supply Chains Another important trend is the composition of tailored services, adapted to the needs of specific users in specific situations, out of basic service elements, potentially offered by different providers. Such a composite service forms a Service Supply Chain (SSC) consisting of one or several service elements. When the user activates the main service, the latter activates service elements as needed, handles the corresponding inputs, waits for deliveries, processes the corresponding outputs and finally returns the result to the user. The latter is sitting at the end of the SSC and has to wait for all service elements to finish before the result can be consumed. I.e., the user perceives the maximum of all response times in the system. In order to control user perception through service management, it is important to determine the weak links of SSC that provide the largest contributions to the response times in order to be able to cope with them in order to improve the user’s QoE perception. A particular case: Map-SSC In this work, we look at a particular service, a map service. These activities are part of a Swedish national project, funded by the Internet Infrastructure Foundation (.se) from funds earned by licensing Swedish Internet domains. We will observe professional users (planners at the municipality) in different stress situations when performing two map-related tasks, downloading a map and clicking a symbol in the displayed map in order to get more detailed information. The latter task relates to a SSC, consisting of a fetch-and-display service and an information service. Furthermore, we will introduce stress on network level by shaping the traffic. This will allow us to correlate user perception with thresholds of QoS parameters and thus to see the impact of user and/or network stress on Service Level Agreements (SLA). The map service provider participating in the project will instrument the SSC such that we will be able to monitor the response time at different places on application level in order to identify the critical links in the SSC. Furthermore, corresponding measurements on network level will be carried out in order to visualize the impact of the network stacks in client and servers, respectively.

Bidraget behandlar sammanhanget mellan användarupplevt tjänstekvalitet och störningar på nätverksnivå med speciell hänsyn till tjänster som formas som kedjor. Det relateras till ett pågående projekt där kvaliten av karttjänster ska kartläggas. Användarupplevt tjänstekvalitet, nätverksprestanda, GIS system, karttjänster