[OpenLayers-Users] compressed and/or binary GML to make the client side happy

[darrepac]

thanks for this information and recommendation.
Is there no way without going into geoserver?
If parsing is not the problem, if I set correctly the bounded box of each
feature, OL is smart enough to only threat the ones which are visible (and
ignore the rest?)?



Christopher Schmidt-4 wrote:
> 
> On Tue, Oct 28, 2008 at 02:17:06PM -0700, darrepac wrote:
>> XML is not the most efficient method to transmit data and, on the client
>> side, when the application try to open the GML, it slows down heavily the
>> machine and it takes age to render.
> 
> The parsing of the GML is unlikely to be the majority of the time here.
> Keep in mind that all of that GML is parsed, and then turned right back
> into XML to display in your browser (SVG is XML-based). In addition, the
> way that OpenLayers works is to constantly update the DOM to change the
> properties of that XML.
> 
> In general, you can't display more than about 50 (IE) - 150 (FF2) - 500
> (FF3/Safari3) vectors at once in a browser. Any more than that, and you
> run into the rendering slowness that you're seeing.
> 
>> I was thinking to compress or at least put in binary the GML file to be
>> more
>> efficient.
> 
> This would be significantly less efficient, since Javascript doesn't
> have any real way to interact with binary data. 
> 
> If you want to try a more efficient transfer format, I recommend
> GeoJSON, which transfers in a format which is very lcose to the
> browser's internal representation. However, with 4000 features, you're
> still going to be completely screwed on performance. You really need to
> look into rendering your data with a server: I recommend GeoServer at
> this point for beginners, because it's relatively easy to get started
> with.
> 
> If you only need to show a few features at a time -- say, you don't mind
> limiting yourself to 200 -- you could put the data behind GeoSErver or
> some other WFS server, and serve with a maxfeatures setting. This would
> limit the number of features displayed at once, and you can generally
> choose the ordering (so you display highest population areas first, for
> example). This would let you maintain your use of vectors, but limit the
> performance headaches, with a "zoom in for more info" (to limit the area
> of the map further, and therefore request fewer features).
> 
> Best of luck,
> -- 
> Christopher Schmidt
> MetaCarta
> _______________________________________________
> Users mailing list
> Users at openlayers.org
> http://openlayers.org/mailman/listinfo/users
> 
> 

-- 
View this message in context: http://www.nabble.com/compressed-and-or-binary-GML-to-make-the-client-side-happy-tp20216202p20217165.html
Sent from the OpenLayers Users mailing list archive at Nabble.com.