Folsom is an Erlang based metrics system inspired by Coda Hale's metrics (https://github.com/dropwizard/metrics). The metrics API's purpose is to collect realtime metrics from your Erlang applications and publish them via Erlang APIs and output plugins. folsom is not a persistent store. There are 6 types of metrics: counters, gauges, histograms (and timers), histories, meter_readers and meters. Metrics can be created, read and updated via the folsom_metrics module.First, regarding using folsom and folsom_webmachine together. To make sure you have compatible versions of each, make sure you use code from the same version tags, ie 0.5 of folsom is known to work with 0.5 folsom_webmachine. HEAD on each repo may have broken API compatibility.