Re: [PATCH] variant Key negotiation on error pages

On 03/20/2013 09:02 PM, Amos Jeffries wrote:

> + rep->header.putStr(HDR_VARY,tmp.termedBuf());
> +
> + // Key:Accept-Language;b="foo"
> + // Only supply the match parameters if the language is actually found.
> + // On the generic reply to all 'unknown' inputs we must be vague like Vary
> + // which makes the recipient use the entire Accept-Language as the variant key.
> + if (err_language) {
> + tmp.append(";b=\"");
> + tmp.append(err_language);
> + tmp.append('"');
> + }
> + rep->header.delById(HDR_KEY);
> + rep->header.putStr(HDR_KEY, tmp.termedBuf());

If I am interpreting draft-fielding-http-key-02 correctly, there is no
point in sending

    Vary: Accept-Language
    Key: Accept-Language

because both of the above header fields have identical semantics
(Section 2). Did I misunderstood? If I did not, you can move the
delById() and putStr() calls inside the err_language if guard (and merge
the two identical if-guards, one after another?).

>> If the negotiated language was "xfo" and the later requested language
>> happens to be "xfoobar", will the "xfo" language response be served to
>> an "xfoobar" reader because of the "prefix match" logic of the b=".."
>> modifier? Is that a good thing?

> Yes and yes. Due to the way the codes are syntaxed the valid ones are
> all 2 or 5 bytes long with an optional trailer.

Well, many languages have three letters in the primary tag (e.g., duh
for Dungra Bhil) and other length are allowed, but what is important
here is whether a language tag may be a prefix of another, completely
unrelated language tag. If yes, then using the prefix b="..." modifier
would be wrong IMHO.

For example, should a cached English ("en") error page be served to an
Emumu-speaking client?

> Type: language
> Subtag: enr
> Description: Emumu
> Description: Emem
> Added: 2009-07-29

> Type: language
> Subtag: en
> Description: English
> Added: 2005-10-16
> Suppress-Script: Latn

I could not find any rules that prohibit one language tag to be a prefix
of another. It is possible that I missed them (not my area of
expertise), but the above counter-example with Emumu/English seems to
indicate that there is no such prohibition?

Thank you,

Alex.
Received on Thu Mar 21 2013 - 04:45:19 MDT