Vidéo pédagogique

3. From pages to resources

Réalisation : 8 septembre 2016 Mise en ligne : 8 septembre 2016
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Descriptif

In this third part, we will see another evolution of the Web, or more precisely, an evolution of the way we use the Web. We will see how we went from a Web essentially linking pages, to a Web linking any resources around us.

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Thèmes
Notice
Langue :
Anglais
Conditions d'utilisation
Unless otherwise specified, the course material is provided under the Creative Commons License BY-NC-ND: the name of the author should always be mentioned; the user can exploit the work except in a commercial context; and he or she cannot make changes to the original work.
Citer cette ressource:
Inria. (2016, 8 septembre). 3. From pages to resources. [Vidéo]. Canal-U. https://www.canal-u.tv/99431. (Consultée le 15 août 2022)
Contacter
Documentation

Encode and decode URLs

URLs only accept ASCII characters. Therefore we need to encode any special characters like accents before we incorporate them into a URL. Try it yourself:

To encode, press the first button...

http://my.site/

To decode, press the second button...

You can change and experiment with other input values for the little scripts above.

Here we see the whole point of the IRI for internationalization and accessibility of the identifiers on the Web.


URI IRI

The translation from URI to IRI back and forth is described in the RFC3987.

The idea is that the IRI is initially encoded in UTF8 then, every IRI character that is not present in the ASCII code is transformed by replacing it with its hexadecimal code preceded by % character.

See also:



URIs for everything...

As we will see later, URIs are used to name a lot of very different things.

Here are some examples:

Namespace and URIs

The notion of namespace is one of the most abstract of this MOOC. Now that we have discussed URIs, let us go back to the notion of namespaces a second time.

Quoting Wikipedia: "In computing, a namespace is a set of symbols that are used to organize objects of various kinds, so that these objects may be referred to by name (...) namespaces are typically employed for the purpose of grouping symbols and identifiers around a particular functionality and to avoid name collisions between multiple identifiers that share the same name."

Since URIs can be used to identify anything, they can be used to identify these sets that form namespaces. You can see namespace as a set of terms that where isolated and that we identify by giving a URI to that set. This allows you to do two important things:

  • to specify that a term you use belongs to a specific set and as a specific meaning just like when you say "I use the word SCORE with the meaning of the University of NICE" as a way to avoid any misunderstanding;
  • to avoid name collisions by prefixing the words (called "qualified name") with prefixes associated with the right namespace for example URI unice: SCORE and sport:SCORE that would make the difference between "results of student exams" and "sport results"; so we can use these two prefixed terms in the same data, documents and applications without any collision or ambiguity.

So you can conceive namespaces as a mechanism to create sets of terms, to identify these sets with URIs and to link these URIs to prefixes that allow to you use terms in a non-ambiguous way.

Famous namespaces include:

REFERENCES

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