See a good description here: http://trac.osgeo.org/openlayers/wiki/Highlighting
(scroll to bottom for WMS highlighting as in this issue title)
WMS highlighting with client side SLD is a technique to highlight features on a
map but without having to fetch the vector data (e.g. via WFS) from the server.
With large amount of features this may save significant bandwidth and
client-side processing within the browser.
From http://trac.osgeo.org/openlayers/wiki/Highlighting :
"One simulates highlighting by drawing a second WMS layer over a WMS layer. The
trick is that a WMS can serve one (or more) features by using a FILTER in an
SLD.
Pros
* OGC compliant, so should work on any WMS supporting SLD.
* Does not have an implicit limit on the number of vertices nor features, so is suitable for numerous complex polygons.
* Can often be faster than WFS, as there's less data being transferred.
* Does not require a WFS server.
* The WMS layer could easily incorporate labels as well as the highlighting.
* It's possible to have different highlight-effects as the styling is includes in the SLD.
Cons
* Only works if your WMS server accepts SLD.
* The resulting layer is WMS, which means no spatial geometry effects, e.g. zooming to the highlighted area.
* requires an extra layer in your mapfile (or other WMS), which is able to retreive ALL geometries from all layers. "
Original issue reported on code.google.com by jus...@gmail.com on 31 Jan 2012 at 7:11
Original issue reported on code.google.com by
jus...@gmail.com
on 31 Jan 2012 at 7:11