As a developer tools analyst, here is a comparison of OpenNMS and Riemann for senior engineers: OpenNMS and Riemann are two distinct open-source projects catering to different aspects of network management. In terms of momentum, OpenNMS, with 1,159 stars and a modest 10 stars gained over the last 30 days, indicates a stable but not rapidly accelerating community interest. Conversely, Riemann, boasting 4,263 stars and 8 new stars in the same period, suggests a larger, though similarly steady, community engagement. The community size, inferred from star counts, is notably larger for Riemann, potentially indicating broader adoption or appeal, possibly due to its innovative approach as a network event stream processing system written in Clojure. OpenNMS, however, targets a more traditional yet critical space as an Enterprise-Grade Network Management Platform, which may attract a more specialized audience. Use cases diverge significantly: OpenNMS is suited for comprehensive network management in enterprise environments, offering a broad set of features for monitoring, troubleshooting, and managing network infrastructure. Riemann, with its stream processing capabilities, is more aligned with real-time event analysis, anomaly detection, and potentially, integration within modern, scalable monitoring stacks, especially those already invested in the Clojure ecosystem or seeking its specific processing advantages. Both projects serve vital, albeit different, needs within the network management and monitoring landscape, reflecting in their community dynamics and growth patterns.