[mapguide-internals] Avoiding unnecessary Tile Cache invalidation (Trac Ticket 1332)

Tue Apr 27 23:48:32 EDT 2010

Uv coded up a solution for option 2, but we are yet to test it and he's
travelling at the moment

if studio/maestro could be aware of this setting, and could check the bounds
for a temp copy of the new map in a session repo before modifying the real
map this could be made a little more robust?

z

On 28 April 2010 13:14, Trevor Wekel <trevor_wekel at otxsystems.com> wrote:
> Option 2 might be appropriate for MGOS 2.2.
>
> Longer term, I think ApplicationDefinition and WebLayout could be extended to reference a "TileSetDefinition" resource.  Any data that takes days or weeks to generate probably merits its own resource type.  Having a separate resource type would also facilitate tile set replication from one server to another.
>
> TileSetDefinition
> {
> ResourceId mapDefinition;
> CoordinateSystem tileSetCoordinateSystem;
> Extent tileSetExtent;
> double[] scales;
> Int tileWidth;
> Int tileHeight;
> Int metaTilingFactor;
> Int32 backgroundColor;
> // other tile related stuff
> }
>
> The TileSetDefinition would be referenced by ApplicationDefinition and WebLayout and the current tiling mechanism in MapDefinition would be deprecated.  TileSetDefinition could also be extended to reference third party tile sets like Google Maps, or even a different MapGuide server.
>
> The pre-rendered tiles would be associated with the TileSetDefinition so MapDefinition changes would not immediately affect rendered tiles.
>
> Regards,
> Trevor
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Walt Welton-Lair
> Sent: April 27, 2010 8:41 PM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] Avoiding unnecessary Tile Cache invalidation (Trac Ticket 1332)
>
> Lots of people have complained about this over the years.  Some options:
>
> - rip out the functionality
>  - benefit: no more unexpected loss of tiles, less server overhead, extremely easy to implement
>  - disadvantage: map authors have to remember to delete invalid tile sets
>
> - add a serverconfig flag (a setting under tile service) to allow disabling the behavior
>  - benefit: no more unexpected loss of tiles, less server overhead, still easy to implement
>
> - design and implement a way to tag/lock individual tile sets, to prevent them from being deleted
>  - disadvantage: requires the most effort
>
>
> I think the second option should be considered.  The default behavior would be to enable the functionality, and it could be turned off for production servers.
>
> Walt
>
> ________________________________________
> From: mapguide-internals-bounces at lists.osgeo.org [mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Zac Spitzer [zac.spitzer at gmail.com]
> Sent: Tuesday, April 27, 2010 10:11 PM
> To: MapGuide Internals Mail List
> Subject: Re: [mapguide-internals] Avoiding unnecessary Tile Cache invalidation  (Trac Ticket 1332)
>
> a base layer group could be treated as a layer?
>
> this is really a frustrating issue for my clients as well
>
> z
>
> On 28 April 2010 11:04, Jason Birch <jason at jasonbirch.com> wrote:
>> WOULD increase (no way of referencing external tile sets currently)
>>
>> On 2010-04-27, Jason Birch <jason at jasonbirch.com> wrote:
>>> My suggestion has always been to treat tile sets as separate resources
>>> and allow them to be included in multiple map definitions. This
>>> increases usefulness and stability all in one go.
>>>
>>> On 2010-04-27, Jackie Ng <jumpinjackie at gmail.com> wrote:
>>>>
>>>> Hi All,
>>>>
>>>> At Zac's suggestion, I'm spawning this thread off of discussions on Trac
>>>> #1332 (http://trac.osgeo.org/mapguide/ticket/1332) to stimulate some more
>>>> discussion on this list.
>>>>
>>>> Sometime last week, I heard a tale of total frustration about how a Tile
>>>> Cache of 1.5 million tiles that was built over 1.5-2 days was instantly
>>>> trashed the moment a dynamic untiled layer was added to the map
>>>> definition
>>>> and saved back into the repository.
>>>>
>>>> That got me thinking about whether something as innocuous as changing the
>>>> description or background color of a map definition w/ tiled layers would
>>>> invalidate the tile cache so I tested this out and just as I feared, it
>>>> indeed wiped out the tile cache.
>>>>
>>>> My initial thoughts were that tiling's only concerned with the base layer
>>>> settings in the Map Definition. So theoretically speaking, doing
>>>> modifications that don't affect the base layers should not affect the
>>>> integrity of the original tiles.
>>>>
>>>> Now according to Tom, there is a whole stack of dependencies that would
>>>> have
>>>> to be checked such as Feature Source changes, Symbol changes, Layer
>>>> Definition changes in order to determine whether a Map Definition's Tile
>>>> Cache needs to be rebuilt. I wonder what overhead would be incurred by
>>>> performing these checks (if it hasn't been done already).
>>>>
>>>> There's also renaming the tile cache directory before saving (also
>>>> suggested
>>>> by Tom) and then renaming back. I wonder what other things can be done so
>>>> that the Tile Cache is cleared *only* if it has to be.
>>>>
>>>> - Jackie
>>>> --
>>>> View this message in context:
>>>> http://osgeo-org.1803224.n2.nabble.com/Avoiding-unnecessary-Tile-Cache-invalidation-Trac-Ticket-1332-tp4971985p4971985.html
>>>> Sent from the MapGuide Internals mailing list archive at Nabble.com.
>>>> _______________________________________________
>>>> mapguide-internals mailing list
>>>> mapguide-internals at lists.osgeo.org
>>>> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
>>>>
>>>
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>
>
>
> --
> Zac Spitzer
> Solution Architect / Director
> Ennoble Consultancy Australia
> http://www.ennoble.com.au
> http://zacster.blogspot.com
> +61 405 847 168
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>

-- 
Zac Spitzer
Solution Architect / Director
Ennoble Consultancy Australia
http://www.ennoble.com.au
http://zacster.blogspot.com
+61 405 847 168