localisation in RESTful services

Question

I have a RESTful service that returns an enum.

I was pondering whether to return integers or strings for an enum value, when it occurred to me that returning a string would depend on the locale of the client.

So how should you handle localisation in REST? Is locale part of conneg?

Answer 1

Localisation is part of content negotiation, and language preferences are specified using the Accept-Language header (RFC).

The RFC is quite strict about what the service is allowed to return here — for instance, if no header is sent, then you may choose any language, but if a header is included, then you may only return one of the requested languages, and are not allowed to fall back to a different language.

In other words, if a resource is only available in English, then a resource requested with Accept-Language: de should return 406 Unacceptable rather than default to presenting the English version.

Other alternatives that don't use the specification but do allow for fallback options are discussed in a couple of other questions (8204816, 7892502).