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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Be careful here however,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Because if the hashing algorithm you choose ever gets ‘broken’
where it’s possible to calculate a binary against a desired result, then people
can potentially overwrite existing assets, etc. A long hash tends to act as a
good barrier against this. (256bit+ is ideal.)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Regards,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Adam<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> opensim-dev-bounces@lists.berlios.de
[mailto:opensim-dev-bounces@lists.berlios.de] <b>On Behalf Of </b>Stefan
Andersson<br>
<b>Sent:</b> Wednesday, 17 December 2008 12:59 AM<br>
<b>To:</b> opensim-dev@lists.berlios.de<br>
<b>Subject:</b> Re: [Opensim-dev] Always mutable assets in OpenSim -- does it
make sense?<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;
font-family:"Verdana","sans-serif"'>First step would probably be to implement
the sha-based binary store that you bring up and that we've discussed earlier,
so that the immutables at least share the same binary data row. Right now, I
believe we're seing massive duplication when people export/import content
between worlds. Storing the binaries separately by sha key would probably be an
low hanging fruit.<br>
<br>
I would say that it's probably very much up to the service (aka 'the grid') how
assets should be managed. On an grid that employs a consumer/producer division
(like a fantasy game) you could probably reap dead assets quite aggressively.
In a SL business model, it becomes harder, as they have to ensure consistent
user experience in a heterogenous environment.<br>
<br>
Best regards,<br>
Stefan Andersson<br>
Tribal Media AB<br>
<br>
> Date: Sun, 14 Dec 2008 14:48:01 +0900<br>
> From: mmazur@gmail.com<br>
> To: opensim-dev@lists.berlios.de<br>
> Subject: [Opensim-dev] Always mutable assets in OpenSim -- does it make
sense?<br>
> <br>
> Hi,<br>
> <br>
> Melanie's recent thread[1] on updating assets prompted me to put in<br>
> writing some thoughts on this topic I've been having.<br>
> <br>
> I'm curious whether it may be beneficial to make assets mutable. AFAIK<br>
> assets are currently immutable because of a LL decisions early on to<br>
> re-use one asset instance for very popular items sold no-modify. This<br>
> makes sense for them because they can:<br>
> <br>
> * clean up unused assets since they own the entire infrastructure<br>
> (regions & DBs)<br>
> * save on space because they anticipate more identical copies rather<br>
> than slightly modified copies<br>
> <br>
> Perhaps taking the opposite approach in OpenSim would be a better fit?<br>
> I mean, copying assets when they are transferred between owners, and<br>
> modifying them if they are modified in-world. I can see a few reasons<br>
> this might be beneficial:<br>
> <br>
> * OpenSim's databases are distributed so cleaning them (reaping dead<br>
> assets) is more difficult<br>
> * with the advent of distributed asset servers and the long-term<br>
> vision of a wide open 3D Internet (like HyperGrid), when an item is<br>
> transferred in-world its assets should probably be stored in that<br>
> avatar's own inventory DB *anyway*<br>
> * disk is cheap, and I wonder which is more wasteful -- multiple<br>
> copies of an asset, each differing slightly due to minor edits over<br>
> time, or multiple copies of identical assets because they correspond<br>
> to different objects in-world<br>
> <br>
> I see this as a cleaner approach to assets for the future. Sure,<br>
> storing duplicate identical assets in a DB can be wasteful, but this<br>
> could be alleviated with hashes of the asset or whatnot (I believe<br>
> this was brought up on this list before).<br>
> <br>
> I realize this change would mean deep, possibly breaking, changes<br>
> throughout the source code, would take a long time to hash out, etc. I<br>
> thought I'd throw it out there anyway.<br>
> <br>
> Your thoughts -- or perhaps clarifications on why this absolutely<br>
> cannot be done -- appreciated :)<br>
> <br>
> Thanks,<br>
> Mike<br>
> <br>
> [1]
https://lists.berlios.de/pipermail/opensim-dev/2008-December/004025.html<br>
> _______________________________________________<br>
> Opensim-dev mailing list<br>
> Opensim-dev@lists.berlios.de<br>
> https://lists.berlios.de/mailman/listinfo/opensim-dev<o:p></o:p></span></p>
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