This EventSource is intended to let out-of-process tools (such as dotnet-counters) do ad-hoc monitoring for the new Instrument APIs. This source only supports one listener at a time. Each new listener will overwrite the configuration about which metrics are being collected and the time interval for the collection. In the future it would be nice to have support for multiple concurrent out-of-proc tools but EventSource's handling of filter arguments doesn't make that easy right now. Configuration - The EventSource accepts the following filter arguments: - SessionId - An arbitrary opaque string that will be sent back to the listener in many event payloads. If listener B reconfigures the EventSource while listener A is still running it is possible that each of them will observe some of the events that were generated using the other's requested configuration. Filtering on sessionId allows each listener to ignore those events. - RefreshInterval - The frequency in seconds for sending the metric time series data. The format is anything parsable using double.TryParse(). Any value less than AggregationManager.MinCollectionTimeSecs (currently 0.1 sec) is rounded up to the minimum. If not specified the default interval is 1 second. - Metrics - A semicolon separated list. Each item in the list is either the name of a Meter or 'meter_name\instrument_name'. For example "Foo;System.Runtime\gc-gen0-size" would include all instruments in the 'Foo' meter and the single 'gc-gen0-size' instrument in the 'System.Runtime' meter. - MaxTimeSeries - An integer that sets an upper bound on the number of time series this event source will track. Because instruments can have unbounded sets of tags even specifying a single metric could create unbounded load without this limit. - MaxHistograms - An integer that sets an upper bound on the number of histograms this event source will track. This allows setting a tighter bound on histograms than time series in general given that histograms use considerably more memory.