Managing multi-tenant edge devices with heterogeneous capabilities scattered across an urban area requires significant communication and computing power, which is challenging when devices are also resource-constrained. These devices play a crucial role in smart city monitoring systems by notifying various municipal organizations about a wide range of ongoing complex events. Some recent approaches in complex event processing use a publish-subscribe architectural pattern to decouple simple event producers from complex event consumers. However, they did not fully address communication efficiency or diverse quality of service (QoS) requirements in aggregating events. This paper proposes a new architecture that integrates the publish-subscribe architectural pattern with software-defined network technology for urban monitoring applications. The architecture enhances monitoring applications with capabilities of distributed processing and detection of complex events. It also enables application developers to define QoS requirements and supports the TESLA complex event specification language. The main focus of our work is on energy and network efficiency. The simulation results demonstrate significant improvements in energy consumption and data packet traffic compared to three close baselines.