Steve, Thanks for the detailed explanation. Sounds like a very logical solution. MapServer is so powerful in its ability to both consume and serv WMS.
The thread caught my eye because my apps typically have a few dozen layers that users can turn on/off in any combination, which makes caching less practical. Best regards, Rich On Tue, Feb 5, 2019 at 8:49 PM Stephen Woodbridge < [email protected]> wrote: > On 2/5/2019 8:52 PM, Richard Greenwood wrote: > > Stephen, > > > > I was watching this thread hoping for a reply to your original > > question because it's an interesting problem. If you have time to > > provide a more detailed explanation of your solution I'd be interested. > > So what I had originally were 7 layers of NOAA ENC (Electronic Nautical > Charts) being pulled from the NOAA WMS service and these were getting > cached locally in mapcache. Since my app was always turning on/off all > seven layers as a set, I wanted to build a new layer that merged all > seven into a single layer. Part of the reason for this was to reduce the > number of layer in openlayers for performance improvements. This would > be just a vertical stacking of the the seven layers into one. Because of > the way NOAA service is structured each layer has a different end point > so it was not possible to have their server do the stacking. > > I eventually found this post: > https://lists.osgeo.org/pipermail/mapserver-users/2012-April/072045.html > which suggests, this might no be the best approach. > > In addition, while looking at this issue I realized the NOAA service > changed it layer definitions for some of the data and my mapcache stuff > was broken as a result. In the end, I decided to create a mapserver > mapfile that did WMS client requests to the NOAA server and broke up the > seven layers into 21 (7 each area, line and point) smaller layers that > allowed for more correct stacking of the data and setting appropriate > MIN/MAX scaledenom values as recommended by the getCapabilities for the > NOAA services. Now I have one mapcache layer that uses the new mosaic > mapfile and this does the vertical stacking which is slow given that > mapserver has to make about 21 WMS requests to serve each metatile > request from mapcache. But the end result is good and tiles are fast > once they are populated. > > Also, I will note that the NOAA ENC service updates the chart data on a > regular basis, so I expire my tiles in the cache after 7 days so they > get regenerated possible using new data. I think because of this, the > strategy of using mapserver to do the stacking and mapcache to handle > the caching is a better division of labor and once the app is converted > to use the new mosaic layer, I'll remove the 7 old layers to free up > disk space. > > Hope this helps someone with a similar issue. > > Best regards, > -Steve W > > > > > Best regards, > > Rich > > > > > > On Tue, Feb 5, 2019 at 4:38 PM Stephen Woodbridge > > <[email protected] <mailto:[email protected]>> > > wrote: > > > > I found response to question by Thomas on this subject that > > suggested it might cause a deadlock if you ran out of connections. > > > > Anyway I decided to build a new map file to do the vertical > > assembly and then cache that through mapcache. > > > > -Steve > > > > Sent from my iPhone > > > > On Jan 27, 2019, at 11:35 PM, Lime, Steve D (MNIT) > > <[email protected] <mailto:[email protected]>> wrote: > > > >> I’ll try to derive something from the source and report back. > >> > ------------------------------------------------------------------------ > >> *From:* mapserver-users <[email protected] > >> <mailto:[email protected]>> on behalf of > >> Stephen Woodbridge <[email protected] > >> <mailto:[email protected]>> > >> *Sent:* Sunday, January 27, 2019 7:08:38 PM > >> *To:* mapserver-users > >> *Subject:* [mapserver-users] mamcache vertical assembly > >> Hi, > >> > >> The mapcache docs has a page for vertical assembly but it is blank > :( > >> > >> I have 7 layers in mapcache and I would like to vertically assemble > >> these into a composite layer. In the past I have been loading all > >> 7 in > >> openlayers but it makes more sense to just composite them into a new > >> layer. There are some scale limits that apply to the various layers. > >> > >> Does anyone have some info on how to do this in mapcache directly > >> rather > >> than create a mapfile and compositing them in mapserver and then > >> making > >> that a new layer in mapcache. > >> > >> Thanks, > >> -Steve W > >> > >> --- > >> This email has been checked for viruses by Avast antivirus software. > >> https://www.avast.com/antivirus > >> > >> _______________________________________________ > >> mapserver-users mailing list > >> [email protected] > >> <mailto:[email protected]> > >> https://lists.osgeo.org/mailman/listinfo/mapserver-users > > _______________________________________________ > > mapserver-users mailing list > > [email protected] > > <mailto:[email protected]> > > https://lists.osgeo.org/mailman/listinfo/mapserver-users > > > > > > > > -- > > Richard W. Greenwood, PLS > > www.greenwoodmap.com <http://www.greenwoodmap.com> > > -- Richard W. Greenwood, PLS www.greenwoodmap.com
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