Soccer meets the requirements of the situated agent approach and as a task domain is sufficiently rich to support research integrating many branches of robotics and AI. A robot is an integrated system, with a controller embedded in its plant. A robotic system is the coupling of a robot to its environment. Robotic systems are, in general, hybrid dynamic systems, consisting of continuous, discrete and event-driven components. Constraint nets provide a semantic model for modeling hybrid dynamic systems. Controllers are embedded constraint solvers that solve constraints in real-time. A controller for our new softbot soccer team, UBC Dynamo98, has been modeled in constraint nets, and implemented in Java, using the Java Beans architecture. The paper demonstrates that the formal constraint net approach is a practical tool for designing and implementing controllers for robots in multi-agent real-time environments.