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<title>[mapguide-internals] RFC required for tile caching changes?</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>A sample tile location would be as
follows:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>……\</span></font> <font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Repositories\TileCache\Samples_Sheboygan_Maps_Sheboygan\7\Base
Layer Group\R2\C3\3_4.png<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The R and C indices correspond to rows and
columns where each row contains 30 tiles vertically and each column contains 30
tiles horizontally.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>This indicates that:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><span style='mso-list:Ignore'>1)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>We’re at zoom level 7<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><span style='mso-list:Ignore'>2)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>We’re in grouped row 2<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><span style='mso-list:Ignore'>3)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>We’re in grouped column 3<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><span style='mso-list:Ignore'>4)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>The tile location within this grouped row/column combination is
(3,4).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The R and C indices never take a zero
value (to avoid issues with negative values around the origin), so this tile
corresponds to a location of (33, 64) in the old scheme.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I took a quick look at the Tile Map
Service Specification, but it doesn’t appear to support the concept of
grouping blocks of tiles into subfolders in its current form. Can you provide
more information on whether this is possible?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Chris.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
mapguide-internals-bounces@lists.osgeo.org
[mailto:mapguide-internals-bounces@lists.osgeo.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Chris Claydon<br>
<b><span style='font-weight:bold'>Sent:</span></b> January 12, 2007 12:47 PM<br>
<b><span style='font-weight:bold'>To:</span></b> MapGuide Internals Mail List<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: [mapguide-internals]
RFC required for tile caching changes?</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>A barrel of worms!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
mapguide-internals-bounces@lists.osgeo.org
[mailto:mapguide-internals-bounces@lists.osgeo.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Jason Birch<br>
<b><span style='font-weight:bold'>Sent:</span></b> January 12, 2007 12:41 PM<br>
<b><span style='font-weight:bold'>To:</span></b> MapGuide Internals Mail List<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: [mapguide-internals]
RFC required for tile caching changes?</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div id=idOWAReplyText94416>
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<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>If you're going to change the storage
schema, how much work would it be to align it with the TMS
specification?</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="http://wiki.osgeo.org/index.php/Tile_Map_Service_Specification"><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>http://wiki.osgeo.org/index.php/Tile_Map_Service_Specification</span></font></a><o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Feel like you've opened a can of worms Chris?</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Jason</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabIndex=-1>
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<p class=MsoNormal style='margin-bottom:12.0pt'><b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
mapguide-internals-bounces@lists.osgeo.org on behalf of Chris Claydon<br>
<b><span style='font-weight:bold'>Sent:</span></b> Fri 2007-01-12 10:39 AM<br>
<b><span style='font-weight:bold'>To:</span></b> MapGuide Internals Mail List<br>
<b><span style='font-weight:bold'>Subject:</span></b> [mapguide-internals] RFC
required for tile caching changes?</span></font><o:p></o:p></p>
</div>
<div>
<p><font size=2 face="Times New Roman"><span style='font-size:10.0pt'>We have
found that problems can occur if too many cached tile images are<br>
stored in a single folder on the hard drive. For this reason, I have<br>
some changes to submit that ensure that we only store 900 tiles per<br>
folder (in 30 x 30 blocks).<br>
<br>
This changes the locations of stored tiles, by introducing new<br>
subfolders, and will thus "orphan" any tiles already created by the<br>
cache. Since the root folder for the tiles for any given map will not<br>
change, these orphaned tiles will be cleaned up if the user modifies the<br>
map definition or makes a call to the Clear(MgMap* map) method in the<br>
tile service API. The user could also force the cleanup simply by<br>
deleting the contents of the root cache folder when they upgrade to the<br>
version containing these changes.<br>
<br>
I'd like to treat this submission as a simple defect fix, but the<br>
requirement for the extra cleanup steps may indicate that an RFC is<br>
required, and I'd like to know the opinions of the PSC on this matter.<br>
<br>
Also, please let me know if you require any further information about<br>
this submission.<br>
<br>
Cheers,<br>
<br>
Chris Claydon.</span></font><o:p></o:p></p>
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