HTTP location

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

Contents

  1. To ask a web browser to load a different web page (URL redirection). In this circumstance, the Location header should be sent with an HTTP status code of 3xx. It is passed as part of the response by a web server when the requested 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. [2] The IETF HTTP working group found that the most popular web browsers tolerate the passing of a 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.aungmyokyaw.com/index.html using

GET/index.htmlHTTP/1.1Host:www.example.com

may get the server response

HTTP/1.1302FoundLocation: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/1.1302FoundLocation:/articles/

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

Relative URL relative path example

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/1.1302FoundLocation: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. [9] [8]

See also

References

  1. ↑ Richardson, Leonard (2007). RESTful Web Services . Sebastopol: O'Reilly. pp.  228–230. ISBN   978-0-596-52926-0.
  2. ↑ "Location". Hypertext Transfer Protocol -- HTTP/1.1. IETF. June 1999. sec. 14.30. doi: 10.17487/RFC2616 . RFC 2616.
  3. ↑ IETF HTTPbis Working Group Ticket 185
  4. ↑ "Location". Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content. IETF. June 2014. sec. 7.1.2. doi: 10.17487/RFC7231 . RFC 7231.
  5. ↑ Uniform Resource Identifier (URI): Generic Syntax. IETF. January 2005. doi: 10.17487/RFC3986 . RFC 3986.
  6. ↑ "IANA Uniform Resource Identifier (URI) Schemes" . Retrieved 2014-11-21.
  7. 1 2 "Relative Reference". Uniform Resource Identifier (URI): Generic Syntax. IETF. January 2005. sec. 4.2. doi: 10.17487/RFC3986 . RFC 3986 . Retrieved 2020-11-22.
  8. 1 2 "Normal Examples". Uniform Resource Identifier (URI): Generic Syntax. IETF. January 2005. sec. 5.4.1. doi: 10.17487/RFC3986 . RFC 3986 . Retrieved 2020-11-22.
  9. ↑ "Merge Paths". Uniform Resource Identifier (URI): Generic Syntax. IETF. January 2005. sec. 5.2.3. doi: 10.17487/RFC3986 . RFC 3986 . Retrieved 2020-11-22.
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