Trailer
The Trailer response header allows the sender to include additional fields at the end of chunked messages in order to supply metadata that might be dynamically generated while the message body is sent, such as a message integrity check, digital signature, or post-processing status.
Note: The TE
request header needs to be set to "trailers" to allow
trailer fields.
Header type | Request header, Response header, Payload header |
---|---|
Forbidden header name | yes |
Syntax
http
Trailer: header-names
Directives
header-names
-
HTTP header fields which will be present in the trailer part of chunked messages. These header fields are disallowed:
-
message framing headers (e.g.,
Transfer-Encoding
andContent-Length
), - routing headers (e.g.,
Host
), -
request modifiers (e.g., controls and conditionals, like
Cache-Control
,Max-Forwards
, orTE
), -
authentication headers (e.g.,
Authorization
orSet-Cookie
), -
or
Content-Encoding
,Content-Type
,Content-Range
, andTrailer
itself.
-
message framing headers (e.g.,
Examples
Chunked transfer encoding using a trailing header
In this example, the Expires
header is used at the end of the chunked
message and serves as a trailing header.
http
HTTP/1.1 200 OK
Content-Type: text/plain
Transfer-Encoding: chunked
Trailer: Expires
7\r\n
Mozilla\r\n
9\r\n
Developer\r\n
7\r\n
Network\r\n
0\r\n
Expires: Wed, 21 Oct 2015 07:28:00 GMT\r\n
\r\n
Specifications
Specification |
---|
HTTP Semantics # field.trailer |
HTTP/1.1 # chunked.trailer.section |
Browser compatibility
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