sane-project-website/old-archive/1999-08/0220.html

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<title>sane-devel: Re: SANE V2</title>
<h1>Re: SANE V2</h1>
<b>Andreas Beck</b> (<a href="mailto:becka@rz.uni-duesseldorf.de"><i>becka@rz.uni-duesseldorf.de</i></a>)<br>
<i>Wed, 18 Aug 1999 01:52:57 +0200</i>
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<i>&gt; Here's an example of the stuff the bh backend writes:</i><br>
<p>
<i>&gt; &lt;xml-stream&gt;</i><br>
snip.<br>
<p>
Yes. I see merit in this. I would actually suggest to always use textual<br>
stuff for things like orientation (orientation 0x01 isn't very <br>
enlightening), and always use units as appropriate (i.e.<br>
&lt;tr&gt;&lt;x&gt;1120mm&lt;/x&gt;... and similar), but I think xml could well be used<br>
for more complex transmissions.<br>
<p>
<i>&gt; Sure, the formatting and parsing remain problems, </i><br>
<p>
Yes and no :<br>
<p>
1. In 99% of the cases, you don't want to make sense of the data right<br>
inside the frontend. You store the stuff away and let a specialized app deal<br>
with it. That keeps parsing out of the frontend.<br>
<p>
2. For those cases wher you do want, you are making use of special features<br>
of a scanner anyway. Adding the proper parsing for the (hopefully few)<br>
features of that scanner shouldn't be so hard.<br>
<p>
<i>&gt; but at least we don't have to get those details into the SANE standard. </i><br>
<p>
Exactly what I am after. And your proposal in deed goes very well together<br>
with mine. It builds three layers of parsing complexity, that can be<br>
implemented optionally on top of each other:<br>
<p>
1. Only RAW data allowed. No parsing, no problem. We have to blind-save or<br>
discard unknown data.<br>
2. RAW + mime-typed data allowed. We have to parse a string to see if it is<br>
something we (or an external helper) understands. If we can't find a match,<br>
we again have to blind-save or discard, or we can let the user choose<br>
what to do, given the type.<br>
3. RAW + mime-typed data + internal data parsing. We have to parse the<br>
mime string, and if we see that it is a format we can handle, we can parse<br>
it further to gather more metadata as required. Fall back to 2., if<br>
we fail to parse.<br>
<p>
90% of apps will be happy with 1.<br>
9 more percent will probably want 2. And those will probably only care for a<br>
few types, or only with those that metamail handles as exernal helper.<br>
And the rest will have to bite the bullet and do 3, which isn't terribly<br>
hard either.<br>
<p>
<i>&gt; I would think that other backends written for scanners with similar </i><br>
<i>&gt; support could follow practice and use the xml encoding approach.</i><br>
<p>
Yes. It is good to set such de-facto standards (if they are flexible enough).<br>
<p>
CU, Andy<br>
<p>
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= Andreas Beck                    |  Email :  &lt;<a href="mailto:andreas.beck@ggi-project.org">andreas.beck@ggi-project.org</a>&gt; =
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<li> <b>Next message:</b> <a href="0221.html">Stephen Williams: "Re: SANE V2"</a>
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