Wireless sensor networks are rapidly being introduced in various application domains, such as medical, defense, and navigation systems. Tremendous advantages of these systems, including cost aspects such as "no-wiring-cost", make these systems persuasive for many industries. However, there are also trade-offs, such as availability (energy consumption) and performance (response time). At the heart of designing suitable software architectures for these systems are conscious decisions about tradeoffs among qualities. This paper outlines some important qualities that are driving the design of a WSN system.