Dioscuri, another application layer protocol

[John Cowan]

On Mon, Sep 28, 2020 at 3:15 AM Sean Conner <sean at conman.org> wrote:

Nope.  The Rubicon was passed earlier this year with talk of the titan:
> protocol which allowed people to upload content to a Gemini server and has
> already been implemented by at least one Gemini server.


You could with equal justice say that publishing Gemini crossed the
Rubicon, since I would certainly never have thought of Dioscuri without
first hearing of Gemini (and being fascinated, since it was clearly a very
nice extension of Gopher's ideas, which I have always loved).


>   What I find sad is that this appears to be separate approach from the
> titan: proposal, which either means the designers of this were not aware of
> of the previous work, or have rejected the previous work for some unstated
> reason---I'm hoping it's the former.
>

I wrote down an early version of Dioscuri when I had barely heard of
Titan.  Later, #gemini pointed me to Titan and I looked at it.  I wasn't
able to find a protocol description and had to reverse engineer it from the
Bash code, but it seemed to me that it was too limited: it provided upload
only, rather than a conversational protocol like I wanted in which
responses were symmetrical with requests.  So I have not so much rejected
Titan as decided that my goals were sufficiently different.


> > The question raised by this isn't just "why Dioscuri?" It's "why should
> > we not use sftp, https, JSON, XML, sexp, IRC, SMTP, foo bar baz frotz
> > for this problem?" That isn't rhetorical. There could be good answers. I
> > just can't think of them.
>

(S)FTP was in fact part of the inspiration for Dioscuri, but I wanted
something much similar.  My earlier version of D. had GET/PUT/POST/DELETE
verbs and the possibility of extensions, but #gemini participants convinced
me that POST was sufficient, provided three cases were well handled:  (a)
no request body (b) no response body (c) the ability to respond with an URL
rather than an anonymous body.  I think I have done that.

JSON, XML, and S-expressions are formats and are all fine: I mentioned JSON
for familiarity, but exchanging information in .INI file format is
perfectly fine (and in fact it can be made isomorphic with XML).

Above all, DIoscuri is both simple and general.  That's not an easy target
to hit, and it's clear to me that Gemini has hit it.  I might quibble about
some details, but I won't.  I have done my best to hit the (slightly
different) target too.

  Again, check the history of this list. It has been discussed before.
>

I read through as much of this year's archives as I could, and I haven't
seen anything bidirectional like this.  Please point me to appropriate
emails if there are any.



John Cowan          http://vrici.lojban.org/~cowan        cowan at ccil.org
He who would do good to another must do it in Minute Particulars;
General Good is the plea of the scoundrel, hypocrite and flatterer:
For Art and Science cannot exist but in minutely organized Particulars.
  --William Blake, il miglior fabbro
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