[Telepathy] Spec meeting notes on Mail Notification interface

Nicolas Dufresne nicolas.dufresne at collabora.co.uk
Thu Jan 21 14:09:24 PST 2010

Key and value are CDATA in the HTML FORM. According to [1],

   "CDATA is a sequence of characters from the document character set"

So no you cannot have binary data with the
application/x-www-form-urlencoded form encoding, and no your initial
example is not a valid use case. Also, the client controls the character
set of the HTML file.

What I was about to introduce in the spec is:

All strings are valid UTF-8 strings. Transforming the UTF-8 string into
valid HTML is the client responsibility (e.g. transform '&' into
'&', etc). Same for transforming UTF-8 string into valid HTTP POST
data (refer to [2] for details about that).
[1] http://www.w3.org/TR/html401/types.html#type-cdata
[2] http://www.ietf.org/rfc/rfc1738.txt

Le jeudi 21 janvier 2010 à 20:47 +0000, Simon McVittie a écrit :
> On Thu, 21 Jan 2010 at 14:39:09 -0500, Nicolas Dufresne wrote:
> > > > > HTTP mostly deals in bytes, not characters.
> > > > 
> > > > We only want to support a specialized form of HTTP POST data
> > > > (x-www-form-urlencoded), which is in ASCII. This data can be passed to
> > > > the browser by creating a temporary HTML file with redirecting form.
> > > 
> > > I see. If that's the case, why don't you just put it in a single string?
> > 
> > In x-www-form-urlencoded POST Data is represented in key/value pair. To
> > generate the HTML file, you would have to parse the single string to
> > split those key/value pairs into HTML nodes (<input type='hidden'
> > name='key'>value</input>).
> Surely that means that we don't want the keys and values to be encoded, at
> which point there's no guarantee that they are in any particular character
> set, bringing us back where we started?
> I agree that x-www-form-urlencoded data ends up as ASCII. However, the
> necessary text to write into an HTML file to produce a desired
> x-www-form-urlencoded POST is not necessarily ASCII.
> Quoting from my earlier mail, suppose the required POST data is a map where
> the keys are bytes 0x01 and 0x80, and the values are equal to the keys. (Note
> that the byte 0x80 is meaningless on its own in UTF-8 - the byte-string '\x80'
> is not valid UTF-8.)
> I agree that the HTTP POST we end up with is %01=%01&%80=%80.
> However, if the client is going to be writing out temporary HTML, neither
> that nor %01 are actually very useful, since what it actually wants is
> something like:
>     <input type="hidden">&#x01;</input>
>     <input type="hidden">&#x80;</input>
> (and then some way to arrange for these to be submitted as latin-1, which is
> a browser-specific can of worms).
> If the implicit assumption you're making is that we only support abstract
> keys and values that are *also* ASCII (i.e. a subset of the set of possible
> HTTP POSTs), with the expectation that all practical webmail systems work like
> that, and in particular that the example I quoted cannot be supported by
> this spec, then please state that assumption/limitation in the spec.
>     Simon
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