This document provides an overview of wireless sensor network software architecture. It discusses the key components of WSNs including sensing units, processing units, power suppliers, and communication devices. It then examines various topics related to WSN software architecture, including network topologies, the IEEE 1451 standard for smart sensors, software architecture components like operating systems and middleware, services in sensor networks, and research challenges around security. The goal is to provide a reliable software architecture for WSNs to enable better performance and functionality.