HTTP location

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The HTTP Location

header field is returned in responses from an HTTP server
under two circumstances:

  1. To ask a web browser to load a different web page (
    URI
    has:
    • Moved temporarily;
    • Moved permanently; or
    • Processed a request, e.g. a POSTed form, and is providing the result of that request at a different URI
  2. To provide information about the location of a newly created resource. In this circumstance, the Location header should be sent with an HTTP status code of 201 or 202.[1]

An obsolete version of the HTTP 1.1 specifications (IETF RFC 2616) required a complete absolute URI for redirection.

relative URL[3] and, consequently, the updated HTTP 1.1 specifications (IETF RFC 7231) relaxed the original constraint, allowing the use of relative URLs in Location headers.[4]

Examples

Absolute URL example

Absolute URLs are URLs that start with a scheme[5] (e.g., http:, https:, telnet:, mailto:)[6] and conform to scheme-specific syntax and semantics. For example, the HTTP scheme-specific syntax and semantics for HTTP URLs requires a "host" (web server address) and "absolute path", with optional components of "port" and "query".

A client requesting
https://www.example.com/index.html
using 

GET /index.html HTTP/1.1
Host: www.example.com

may get the server response 

HTTP/1.1 302 Found
Location: https://www.example.org/index.php

Relative URL absolute path example

Relative URLs are URLs that do not include a scheme or a host. In order to be understood they must be combined with the URL of the original request.

A client request for
https://www.example.com/blog/all:
may get a server response with a path that is absolute because it starts with a slash:[7] 

HTTP/1.1 302 Found
Location: /articles/

The URL of the location is expanded by the client to
https://www.example.com/articles/.[8]

Relative URL relative path example

[9]

A client request for
https://www.example.com/blog/latest
may get a server response with a path that is relative because it doesn't start with a slash:[7] 

HTTP/1.1 302 Found
Location: 2020/zoo

The client removes the path segment after the last slash of the original URL and appends the relative path resulting in
https://www.example.com/blog/2020/zoo.[10][8]

See also

References

  1. ISBN 978-0-596-52926-0
    .
  2. doi:10.17487/RFC2616. RFC 2616
    .
  3. ^ IETF HTTPbis Working Group Ticket 185
  4. doi:10.17487/RFC7231. RFC 7231
    .
  5. doi:10.17487/RFC3986. RFC 3986
    .
  6. ^ "IANA Uniform Resource Identifier (URI) Schemes". Retrieved 2014-11-21.
  7. ^
    doi:10.17487/RFC3986. RFC 3986
    . Retrieved 2020-11-22.
  8. ^
    doi:10.17487/RFC3986. RFC 3986
    . Retrieved 2020-11-22.
  9. doi:10.1093/gao/9781884446054.article.t087366
    .
  10. doi:10.17487/RFC3986. RFC 3986
    . Retrieved 2020-11-22.
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