Absolute urls, relative urls, and…?

StackOverflow https://stackoverflow.com/questions/904046

  •  05-09-2019
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Question

I am writing some documentation and I have a little vocabulary problem:

  1. http://www.example.com/en/public/img/logo.gif is called an "absolute" url, right?
  2. ../../public/img/logo.gif is called a "relative" url, right?
  3. so how do you call this: /en/public/img/logo.gif ?

Is it also considered an "absolute url", although without the protocol and domain parts?

Or is it considered a relative url, but relative to the root of the domain?

I googled a bit and some people categorize this as absolute, and others as relative.

What should I call it? A "semi-absolute url"? Or "semi-relative"? Is there another word?

Was it helpful?

Solution

Here are the URL components:

http://www.example.com/en/public/img/logo.gif
\__/   \_____________/\_____________________/
 #1     #2             #3
  1. scheme/protocol
  2. host
  3. path

A URL is called an absolute URL if it begins with the scheme and scheme specific part (here // after http:). Anything else is a relative URL.

A URL path is called an absolute URL path if it begins with a /. Any other URL path is called a relative URL path.

Thus:

  • http://www.example.com/en/public/img/logo.gif is a absolute URL,
  • ../../public/img/logo.gif is a relative URL with a relative URL path and
  • /en/public/img/logo.gif is a relative URL with an absolute URL path.

Note: The current definition of URI (RFC 3986) is different from the old URL definition (RFC 1738 and RFC 1808).

The three examples with URI terms:

  • http://www.example.com/en/public/img/logo.gif is a URI,
  • ../../public/img/logo.gif is a relative reference with just a relative path and
  • /en/public/img/logo.gif is a relative reference with just an absolute path.

OTHER TIPS

It is sometimes called a virtual url, for example in SSI:

<!--#include virtual = "/lib/functions.js" -->

From the Microsoft's documentation about Absolute and Relative URLs

A URL specifies the location of a target stored on a local or networked computer. The target can be a file, directory, HTML page, image, program, and so on.

An absolute URL contains all the information necessary to locate a resource.

A relative URL locates a resource using an absolute URL as a starting point. In effect, the "complete URL" of the target is specified by concatenating the absolute and relative URLs.

An absolute URL uses the following format: scheme://server/path/resource

A relative URL typically consists only of the path, and optionally, the resource, but no scheme or server. The following tables define the individual parts of the complete URL format.

  • scheme - Specifies how the resource is to be accessed.

  • server - Specifies the name of the computer where the resource is located.

  • path - Specifies the sequence of directories leading to the target. If resource is omitted, the target is the last directory in path.

  • resource - If included, resource is the target, and is typically the name of a file. It may be a simple file, containing a single binary stream of bytes, or a structured document, containing one or more storages and binary streams of bytes.

Keep in mind just how many segments of the URL can be omited, making them relative (note: its all of them, just about). These are all valid URLs:

  • http://example.com/bar?baz
  • ?qoo=qalue
  • /bar2
  • dat/sly
  • //auth.example.com (most people are surprised by this one! Will use http or https, depending on the current resource)
  • #anchor

I have seen it called a root relative URL.

Facebook would call /en/public/img/logo.gif a protocol-relative URL (see their batch API).

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