In this paper, we present a practical approach to generate the constraint engine for an effective constraint-based intrusion detection system (IDS). The IDS framework was designed for safety-sensitive networks that involve limited-access closed networks such as the networks for command and control systems or Air Traffic Control (ATC) systems. The constraint engine generated by the framework supports real-time performance while ensuring the intended, normal behaviour of its target networks. We present the IDS framework in terms of its internal DSL representation as well as its transformation mechanisms to generate the constraint engine code. Comparing the autogenerated version against a manually implemented, optimized version of the constraint engine indicates no significant difference in terms of their performance.