// See https://github.com/aspnet/AspNetCore/blob/master/src/Hosting/Hosting/src/Internal/HostingApplicationDiagnostics.cs
public static void InitFromMessageHeaders(this Activity activity, MessageHeaderCollection headers)
{
var traceId = headers.GetValue(DiagnosticsConstants.TraceIdHeaderKey);
if (!string.IsNullOrEmpty(traceId))
{
// This will reflect, that the current activity is a child of the activity
// which is represented in the message.
activity.SetParentId(traceId);
var traceState = headers.GetValue(DiagnosticsConstants.TraceStateHeaderKey);
if (!string.IsNullOrEmpty(traceState))
{
activity.TraceStateString = traceState;
}
// We expect baggage to be empty by default.
// Only very advanced users will be using it in near future, we encourage them to keep baggage small (few items).
var baggage = headers.GetValue(DiagnosticsConstants.TraceBaggageHeaderKey);
if (BaggageConverter.TryDeserialize(baggage, out var baggageItems))
{
activity.AddBaggageRange(baggageItems);
}
}
}
public static void SetMessageHeaders(this Activity activity, MessageHeaderCollection headers)
{
if (activity?.Id == null)
{
throw new InvalidOperationException(
"Activity.Id is null. Consider to start a new activity, before calling this method.");
}
headers.Add(new MessageHeader(DiagnosticsConstants.TraceIdHeaderKey, activity.Id));
var traceState = activity.TraceStateString;
if (traceState != null)
{
headers.Add(DiagnosticsConstants.TraceStateHeaderKey, traceState);
}
if (activity.Baggage.Any())
{
headers.Add(new MessageHeader(DiagnosticsConstants.TraceBaggageHeaderKey,
BaggageConverter.Serialize(activity.Baggage)));
}
}
