Validating Internationalized URLs - Is this going to be a problem?

Question

After reading about the new Arabic URLs, and with more languages to come, how should URL validation be done for internationalized applications? Does the validation change at all and will existing solutions break? Is regex still a good approach? If so, what would that regex look like? If not, what's a good strategy? What are some good resources to read more on the topic?

I ask this because it has the potential to cause a good many localized applications to have to be rewritten if they have to validate URLs at any point.

Answer 1

Some relevant standards:

• RFC 3492: Internationalized Domain Names in Applications (IDNA)
• Updated draft which would modify/update RFC 3492 for this latest change
• IDNA Working Group homepage on IETF

Since it's a brand new thing I'm unable to find a good solid reference for how to do so (if you can reliably do so), but I've been able to find lots of potential starting points so I'm making this a CW so people can update if they find more relevant info.