Custom HTTP header

Mark Wahl Mark.Wahl at
Tue Dec 6 00:42:24 UTC 2005

Ernst Johannes wrote:

 > Does anybody know what the current standard (or failing that, best  practice) is for adding custom HTTP headers on 
the server-to-client leg.
 > seems to have been proposed and never passed?

FWIW Proposed Standard RFC 3229, Delta encoding in HTTP, two years later,
did not use the RFC2774 mechanism to define its entity headers.  It said:

"10.5 Header specifications

    The following headers are defined, for use as entity-headers.  (Due
    to the terminological confusion discussed in section 3, some entity-
    headers are more properly associated with instances than with

  10.5.1 Delta-Base

    The Delta-Base entity-header field is used in a delta-encoded
    response to specify the entity tag of the base instance.

       Delta-Base = "Delta-Base" ":" entity-tag

I'm assuming X-Yadis-Location is an an entity-header (e.g. Content-Location,
Content-Type) not a response-header (e.g. Location).

BTW you also might want to look at section 9.2 (OPTIONS) of RFC 2616.

"This method allows the client to determine the options and/or
  requirements associated with a resource, or the capabilities
  of a server, without implying a resource action or initiating
  a resource retrieval....

  A 200 response SHOULD include any header fields that indicate
  optional features implemented by the server and applicable to that
  resource (e.g., Allow), possibly including extensions not defined by
  this specification."

And at the following internet-draft:

Mark Wahl
Informed Control Inc.

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