science

Internationalized Resource Identifier

Internationalized Resource Identifier is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Internationalized Resource Identifier rather than just read about it. In short: The Internationalized Resource Identifier (IRI) is an internet protocol standard which builds on the Uniform Resource Identifier (URI) protocol by greatly expanding the set of permitted characters. It was defined by the Internet Engineering Task Force (IETF) in 2005 in RFC 3987.

Key takeaways

Internationalized Resource Identifier belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Internationalized Resource Identifier to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Internationalized Resource Identifier from memory before moving on to harder problems.

Reference excerpt

The Internationalized Resource Identifier (IRI) is an internet protocol standard which builds on the Uniform Resource Identifier (URI) protocol by greatly expanding the set of permitted characters. It was defined by the Internet Engineering Task Force (IETF) in 2005 in RFC 3987. While URIs are limited to a subset of the US-ASCII character set (characters outside that set must be mapped to octets according to some unspecified character encoding, then percent-encoded), IRIs may additionally contain most characters from the Universal Character Set (Unicode/ISO 10646), including Chinese, Japanese, Korean, and Cyrillic characters.

Syntax IRIs extend URIs by using the Universal Character Set, where URIs were limited to ASCII, with far fewer characters. IRIs may be represented by a sequence of octets but by definition are defined as a sequence of characters, because IRIs may be spoken or written by hand.

Compatibility IRIs are mapped to URIs to retain backwards-compatibility with systems that do not support the new format. For applications and protocols that do not allow direct consumption of IRIs, the IRI should first be converted to Unicode using canonical composition normalization (NFC), if not already in Unicode format. All non-ASCII code points in the IRI should next be encoded as UTF-8, and the resulting bytes percent-encoded, to produce a valid URI. Example: The IRI https://en.wiktionary.org/wiki/Ῥόδος becomes the URI https://en.wiktionary.org/wiki/%E1%BF%AC%CF%8C%CE%B4%CE%BF%CF%82 ASCII code points that are invalid URI characters may be encoded the same way, depending on implementation. This conversion is easily reversible; by definition, converting an IRI to an URI and back again will yield an IRI that is semantically equivalent to the original IRI, even though it may differ in exact representation. Some protocols may impose further transformations; e.g. Punycode for DNS labels.

Advantages There are reasons to see URIs displayed in different languages; mostly, it makes it easier for users who are unfamiliar with the Latin (A–Z) alphabet. Assuming that it isn't too difficult for anyone to replicate arbitrary Unicode on their keyboards, this can make the URI system more accessible.

Disadvantages Mixing IRIs and ASCII URIs can make it much easier to execute phishing attacks that trick someone into believing they are on a different site than they really are. For example, one can replace an ASCII "a" in www.myfictionalbank.com with the Unicode look-alike "α" to give www.myfictionαlbank.com and point that IRI to a malicious site. This is known as an IDN homograph attack. While a URI does not provide people with a way to specify web resources using their own alphabets, an IRI does not make clear how web resources can be accessed with keyboards that are not capable of generating the requisite internationalized characters. This means that IRIs are now handled in a way very similar to many other software which might require the use of a non-keyboard input method when dealing with texts in various languages.

See also IDN (Internationalized Domain Name) Semantic Web Punycode XRI (Extensible Resource Identifier)

References

External links RFC 3987: Proposed Standard of Internationalized Resource Identifiers (IRIs) W3C Internationalization Activity IANA List of Registered URI Schemes Survey of use of IRIs in W3C Specs

Worked examples

Example 1 — a first encounter with Internationalized Resource Identifier

Start with the simplest possible case. Write down what Internationalized Resource Identifier claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Internationalized Resource Identifier before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Internationalized Resource Identifier ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Internationalized Resource Identifier

In research: Internationalized Resource Identifier appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Internationalized Resource Identifier in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Internationalized Resource Identifier is common in secondary-school and first-year university syllabi. It links to neighbouring topics Application layer protocols, Internet Standards, Internet protocols, so understanding it makes those chapters shorter.
In everyday life: Look for Internationalized Resource Identifier outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Internationalized Resource Identifier in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Internationalized Resource Identifier means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Internationalized Resource Identifier out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Internationalized Resource Identifier in simple terms?

Why does Internationalized Resource Identifier matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Internationalized Resource Identifier?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Internationalized Resource Identifier.