We present a compiler-based approach to the design and engineering of complex real-time systems. The systems are built from computation, communication and I/O subsystems, based on different extant real-time models and schemes. We have defined a high-level system specification language, called Real-Time System Markup Language (RTSML), for integration of model-specific subsystems. We have developed a prototype extensible compiler from RTSML to a Constraint Logic Programming (CLP) language. Model-specific compiler modules can be added that generate CLP code for subsystems based on the corresponding real-time models and schemes, and their integration with other subsystems of a complex real-time system being specified. We specify an example system consisting of dozens of communicating real-time tasks that share real-time computation and communication resources, and map it to two problem solving approaches. The first one is the conventional CLP search, while the second one is suitable for system reconfiguration when system parameters change dynamically. We compare the two approaches and present their timings for the example system.Based on the results obtained, and potentials of the software technologies used in our compiler-based approach, it appears promising for large-scale complex real-time systems.