With the increasing complexity of information systems, it is becoming increasingly unclear as to how information system behaviors relate to stated requirements. Although requirements documents and Business Activity Monitoring can provide static and dynamic evidence for requirements compliance, neither provides a formal, real-time presentation of requirements satisfaction.The REQMON research project is constructing and validating methods and tools for requirements specification and real-time monitoring. The challenge is to simplify monitoring system construction while ensuring the fidelity and expressiveness of its feedback. To address this challenge, our integrative approach leverages a formal monitoring abstraction layer, dynamically configurable distributed monitors, and commercial software to define a theory for specifying, developing, and analyzing requirements monitoring systems.This article presents an implementation of rule-based monitors, which are derived from system requirements. Such an implementation can simplify the specification of temporal requirements monitors and can be efficient, as our analysis shows.