Monitor services deployable on device networks may be implemented using a modular approach, in which a core monitor service is mapped to one or more devices included in, or associated with, the device networks. Additional monitoring-related functionality may be provided to such devices using plug-ins, add-on services or service components, or other service modules, which interact with the core monitor service. The core monitor service(s) and any monitor service modules may be mapped, to specific ones of the devices, based on, for example, requirements of other services and/or relevant device metadata (e.g., capabilities) of the devices. In additional or alternative implementations, various protocols may be used to register new devices and deployed monitor service(s) with the distributed monitoring service(s) in a fast, secure, energy-efficient, and reliable manner, even as devices join or leave the device network(s).