// See https://github.com/aspnet/AspNetCore/blob/master/src/Hosting/Hosting/src/Internal/HostingApplicationDiagnostics.cs
public static void InitFromMessageHeaders(this Activity activity, MessageHeaderCollection headers)
{
string?traceId = headers.GetValue(DefaultMessageHeaders.TraceId);
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);
string?traceState = headers.GetValue(DefaultMessageHeaders.TraceState);
if (!string.IsNullOrEmpty(traceState))
{
activity.TraceStateString = traceState;
}
// The baggage is parsed last, so if it fails to be deserialized the rest is still setup.
// 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).
string?baggage = headers.GetValue(DefaultMessageHeaders.TraceBaggage);
if (baggage != null)
{
var baggageItems = ActivityBaggageSerializer.Deserialize(baggage);
AddBaggageRange(activity, 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(DefaultMessageHeaders.TraceId, activity.Id));
var traceState = activity.TraceStateString;
if (traceState != null)
{
headers.Add(DefaultMessageHeaders.TraceState, traceState);
}
if (activity.Baggage.Any())
{
headers.Add(
new MessageHeader(
DefaultMessageHeaders.TraceBaggage,
ActivityBaggageSerializer.Serialize(activity.Baggage)));
}
}
