Request for Header Field normalisation

[oalders]

Migrated from rt.cpan.org#105516 (status was 'new')

Requestors:

• [email protected]

From [email protected] on 2015-06-26 22:49:46:

Hi all,

I just wrote YA caching UA (with Moo and CHI), and I found something I wasn't able to commit time to. So, just in case anybody else is inspired, I submit this as a wishlist item. :-)

Section 4.1 in RFC 7234 see http://tools.ietf.org/html/rfc7234#section-4.1 requires normalization of the Vary header values. I figured this normalization is better done in HTTP-Message than in the caching UA.

Cheers,

Kjetil

[vanHoesel]

@kjetilk, As far as I understand what is written in RFC 7234 §4.1 Calculating Secondary Keys with Vary, it does not say anything about the normalisation of the VARY response header itself. That can be just a list of nominated header-field names, in any order or capitalisation.

The RFC does explain what can be done with the presented request-header fields and/or associated request-header fields to see if it is a match or not:

• adding/removing whitespace
• combining fields, for multi value fields
• reordering fields
• capitalisation

Normalisation of the VARY header 'ansich' is not the issue you have to deal with. But what you typically want is the normalisation of each and every header-field mentioned.

You may be looking for something like $h->normalized_header( $field ) in HTTP::Headers, but it ain't there (yet)

I think, because of misinterpretation of the RFC, this specific issue may be closed, and maybe a new one could be opened 'HTTP::Headers normilized headers request'

[kjetilk]

Yes, indeed, a $h->normalized_header( $field ) in HTTP::Headers is what I'm looking for. I thought that was clear when I wrote "Vary header values", sorry it wasn't clear enough.

Wouldn't it be better to just change the title of the issue than taking the extra effort to open a new issue?

[vanHoesel]

Sounds like a plan, but than I think we should ask @oalders to update the title. As that does not reflect the request you really have:

What about:

---

Title: Request for Header Field normalisation

Reasoning:

In order to make comparison of two Header Field values more convenient (and correct) it would be great to have a normalisation function in HTTP::Headers, like:

my $normalized_value = $h->normalized_header( 'accept_language');

Normalisation is mentioned in RFC 7234 §4.1 Calculating Secondary Keys with Vary. And could involve:

• adding/removing whitespace
• combining fields, for multi value fields
• reordering fields
• capitalisation

However, re-ordering and capitalisation can be Header Field dependent and should not break semantics

---

Well, I think I just wrote out a new issue ?

[kjetilk]

Hehe, right, indeed, that is a well formulated new issue :-) Feel free to post it like that.

[vanHoesel]

@genio , thank You for renaming, you might want to rename it back, rather than rewriting history - unless you really really really want the discussion be part of the introduction. As @kjetilk said, posting a new one, see #116

[oalders]

Thanks everyone!