[ZPT] response.setHeader() best practice

Tue, 09 Apr 2002 14:48:18 +0200

Hi,

--On Tuesday, April 09, 2002 05:46:59 +0000 Alan Kennedy <zpt@xhaus.com> 
wrote:

>> After all, setting HTTP Headers is not presentation but
>> content. So its best placed in scripts.
>
> I don't think it's a case of presentation vs content, I
> think it's a case of whether
>
> A. Content meta-data belongs in the HTTP header
>
> or
>
> B. Content meta-data belongs in the HTTP body (i.e. the
> content).
>
> In the case of the character encoding, it's an easy choice:
> it has to go in the HTTP header. If not, then you have a
> bootstrap problem: The character set encoding is in the
> content, so you have to read the content to find out what
> it is. But you can't decode the content until you know what
> character encoding it is......
> Similar considerations apply to "content-type", "content-
> length", etc. But let's focus on character encoding for the
> sake of argument.
>
> Both HTTP *and* HTML allow you to specify character
> encoding, the former in the "Content-Type" HTTP header, and
> the latter in <meta> tags under the <head>.
>
> However, the HTML <meta> element type, e.g.,
>
> <meta http-equiv="Content-Type" content="text/html;
> charset=iso-8859-1"/>
>
> was invented for the sole purpose of allowing the document
> author to communicate meta-data about the document *to the
> server*, so it still the servers responsibility to
> communicate the character encoding in the HTTP header.
>
> The recommended server behaviour for web servers which are
> serving HTML content is for them to
>
> 1. Parse the content of HTML files (at least up to the end
> of the </head>).
> 2. Extract such meta information from the document
> 3. Set HTTP headers containing the document meta
> information, as specified by the document.
>
> http://www.w3.org/TR/html401/struct/global.html#edef-META
>
> So I think the real answer to this question lies in the
> server behaviour.
>
> 1. Does the server which transmits the resources (currently
> only Zope) follow the steps outlined above?
> 2. Will all servers which contain implementations of
> ZPT/TAL follow the same guidelines?

For Zope it could read it at document creation or change time
rather then at publishing time.
>
> If the answer to either of these questions is no, then I
> think the application developer has the following options.
>
> 1. Modify the server behaviour, through either
> reconfiguration or reprogramming, so that it does behave
> correctly.
>
> 2. Rely on the user-agent's (browser's) ability to guess
> the meta information.
>
> 3. Fall back to explicitly modifying the HTTP header, using
> script commands, during creation of the document.
>
> I think. I might be wrong :-)
>
> Alan Kennedy.

No, thats right :-)

Regards
Tino