Re: [Ietf-message-headers] Permanent message header field registration for traceparent and tracestate

Philippe Le Hégaret <plh@w3.org> Sun, 24 November 2019 20:46 UTC

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To: Julian Reschke <julian.reschke@gmx.de>, "ietf-message-headers@lists.ietf.org" <ietf-message-headers@lists.ietf.org>
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Subject: Re: [Ietf-message-headers] Permanent message header field registration for traceparent and tracestate
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On 11/24/2019 3:39 PM, Julian Reschke wrote:
> The spec link's anchor doesn't work for me.
> <https://www.w3.org/TR/trace-context/#traceparent-header> does, though.

Didn't check and realize the links had changed. Here is an updated template:

[[
Header field name: traceparent
Applicable protocol: http
Status: permanent
Change Controller:
   Distributed Tracing Working Group
   https://www.w3.org/2018/distributed-tracing/
   public-trace-context@w3.org
Specification:
   https://www.w3.org/TR/trace-context/#traceparent-header

Header field name: tracestate
Applicable protocol: http
Status: permanent
Change Controller:
   Distributed Tracing Working Group
   https://www.w3.org/2018/distributed-tracing/
   public-trace-context@w3.org
Specification:
   https://www.w3.org/TR/trace-context/#tracestate-header
]]

> Quoting:
> 
>> 3.2 Traceparent Header
>>
>> The traceparent HTTP header field identifies the incoming request in a 
>> tracing system. It has four fields:
>>
>>     version
>>     trace-id
>>     parent-id
>>     trace-flags
> 
> So what is the actual syntax of the header field?

It's mentioned in the section
[[
[...]
   The tracestate field value is a list of [list-members] separated by 
[commas].

[...]

list  = list-member 0*31( OWS "," OWS list-member )
list-member = key "=" value
list-member = OWS

[...]

key = lcalpha 0*255( lcalpha / DIGIT / "_" / "-"/ "*" / "/" )
key = ( lcalpha / DIGIT ) 0*240( lcalpha / DIGIT / "_" / "-"/ "*" / "/" 
) "@" lcalpha 0*13( lcalpha / DIGIT / "_" / "-"/ "*" / "/" )
lcalpha    = %x61-7A ; a-z

[...]

value    = 0*255(chr) nblk-chr
nblk-chr = %x21-2B / %x2D-3C / %x3E-7E
chr      = %x20 / nblk-chr
]]
https://www.w3.org/TR/trace-context/#tracestate-header-field-values

Philippe