Due to the shared medium nature of wireless networks, the uncertainties caused by collisions and interferences make the Quality of Service (QoS) issue harder than its wired counterpart. Many publications have been focused on network and MAC layer design to address the QoS issue in wireless networks. However, the middleware design has been overlooked. For QoS support, we need to map the QoS requirement of applications to performance metrics. Middleware is the place we do such mapping. In this paper, we use packet level priority to bridge the QoS requirements and performance. Through middleware priority adaptation, we aim to make the premium traffic meet the QoS requirement, we study the impact of middleware priority adaptation on QoS performance, including bandwidth and end-to-end delay, via experiments with multimedia flows over IEEE 802.11 environment. Our evaluation is based on experiments in both WLAN and ad hoc network environment. Our investigation shows that middleware adaptation is efficient in assisting to achieve QoS in many scenarios.