Reporter can't provide feedback on success

[jcchavezs]

Currently reporter is not providing any feedback about the call to the zipkin server, if it fails it logs the error and don't fail and more so if it success, it won't notify the user about it.

This is alright in normal situations but can be a bit obscure in tooling, for example: https://github.com/jcchavezs/jaeger2zipkin/blob/master/Main.php#L53

One option is to add a debug log line on success. Any ideas @anuraaga @adriancole @basvanbeek ?

[codefromthecrypt]

in java we use metrics for this, and the metrics handler could be overridden to use console if you wanted. granted in java, typically the underlying http libraries can log something so we don't have as much need to redo that.

putting logging on a common path can be tricky, so if you do be careful and guard it well so that it isn't on. normal users should not need to ever see this.

[jcchavezs]

We used to use metrics too but we dropped as none used and also it was hard to know what error was it (e.g. on debug as we are using curl underneath).

[codefromthecrypt]

as logging can flood the console, we only handle first error at warn level (this is in the async reporter) then FINE afterwards (similar to DEBUG level) openzipkin/zipkin-reporter-java#155