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Re: data URIs - filename and content-disposition

From: Michael A. Puls II <shadow2531@gmail.com>
Date: Sat, 27 Feb 2010 11:09:17 -0500
To: "Julian Reschke" <julian.reschke@gmx.de>
Cc: uri@w3.org
Message-ID: <op.u8sm5qi61ejg13@sandra-svwliu01>
On Fri, 26 Feb 2010 09:52:14 -0500, Julian Reschke <julian.reschke@gmx.de>  
wrote:

> On 26.02.2010 15:33, Michael A. Puls II wrote:
>> ...
>>>>> So I have a slight preference to keep things simple, and to focus on
>>>>> the specific use case.
>>>>
>>>> Well, I'm personally happy with just:
>>>>
>>>> data:text/plain;charset=utf-8;content-disposition=attachment;filename=name,
>>>>
>>>>
>>>> (that could even be shortened to just disposition=attachment)
>>>>
>>>> I just suggested the more flexible way as I figured that's what most
>>>> people would want.
>>>>
>>>> Now, if we do it just the simple way, how should the filename value be
>>>> encoded? Just percent-encoded UTF-8? That'd be fine by me because I
>>>> could just use encodeURIComponent() to produce the value.
>>>
>>> We'll need to define which characters need to be percent-escaped,
>>> though. Obviously all non-URI characters, but also those needed to
>>> parse the parameters, so minimally ";".
>>
>> Well, encodeURIComponent basically percent-encodes anything not in
>> "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.!~*'()"
>>
>> , which is great to me. That covers encoding ; too.
>> ...
>
> Let's see. The data URI scheme RFC (RFC2397) uses token/attribute/value  
> from RFC 2045, which has  
> (<http://greenbytes.de/tech/webdav/rfc2045.html#rfc.section.5.1>):
>
>       value := token / quoted-string
>
>       token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
>                   or tspecials>
>
>       tspecials :=  "(" / ")" / "<" / ">" / "@" /
>                     "," / ";" / ":" / "\" / <">
>                     "/" / "[" / "]" / "?" / "="
>                     ; Must be in quoted-string,
>                     ; to use within parameter values
>
> so any new data URI parameter should accept both tokens and quoted  
> strings.
>
> Also, tspecials appears to include a few things encodeURIComponent  
> doesn't.
>
> The devil is in the details. This will need examples and test cases.

See <http://shadow2531.com/opera/testcases/datauri/data_uri_rules.html>  
and the example link at the bottom of that page. That's how I'd parse data  
URIs and how I'd support filename and content-disposition.

-- 
Michael
Received on Saturday, 27 February 2010 16:09:52 UTC

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