AW: [OpenLayers-Users] How to make Openlayers to request the vector data every manipulation of map

[Arnd Wippermann]

maybe adding the param resFactor to the BBOX.Strategy will solve your
problem.
 
strategies: [new OpenLayers.Strategy.BBOX({ratio: 1.1, resFactor:1})], 

Arnd


  _____  

Von: openlayers-users-bounces at lists.osgeo.org
[mailto:openlayers-users-bounces at lists.osgeo.org] Im Auftrag von Bartlomiej
Burkot
Gesendet: Donnerstag, 8. März 2012 16:57
An: openlayers-users at lists.osgeo.org
Betreff: [OpenLayers-Users] How to make Openlayers to request the vector
data every manipulation of map


Hello,

I think I have exactly the same problem. I have vector layer with many
points-markers. I need to limit the number of fetched points from server
becouse of performance.
The vectorlayer use bbox strategy and protocol HTTP:

weather_points_layer = new OpenLayers.Layer.Vector("Wetterpunkte", {
                
                strategies: [new OpenLayers.Strategy.BBOX({ratio: 1.1})], 

                protocol: new OpenLayers.Protocol.HTTP({
                    url: "text_layer_generator/weather_points.php"
                ..
                })
            });

The script: weather_points.php limits the number of points using bbox
parameter and LIMIT statement in sql query.
There is the working example: http://mapakrakow.pl/pogoda/test.php
When I zoomin the points are not fetched from server but from browser cache.
Problem is that when you zoomin to - for example  Berlin - you don't see any
points. There is not any request in firebug fetching the data.

Running this command:
weather_points_layer.refresh({force:true}); 
in firebug console Openlayers requests and refreshes the data from server
correctly and shows points over Berlin.
I tryed to change cache-control headers in weather_points.php:

#header("Cache-Control: max-age=2"); // HTTP/1.1
#header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); // Date in the past
#header("Pragma: Cache"); // required 
//header("connection: close");
//Keep-Alive    timeout=2, max=100

and add the refresh strategy:
strategies: [new OpenLayers.Strategy.BBOX({ratio: 1.1}), new
OpenLayers.Strategy.Refresh()], 

but both didn't helped.
I fond this article:
http://stackoverflow.com/questions/2995238/how-to-refresh-reload-a-kml-layer
-in-openlayers-dynamic-kml-layer
But I don't need to refresh vectorlayer in constant time interval but every
time when user manipulates the map.

Has someone experience how to solve this problem?
Thanks for your help.

Bartlomiej Burkot


W dniu 2012-03-07 16:56, Jan Hartmann pisze: 

No, it tried that. According to the documentation, the redraw function does
not take a parameter.

Jan

On 03/07/2012 04:45 PM, Steve.Toutant at inspq.qc.ca wrote: 


Is this working? 
vectorLayer.redraw(true);





Jan Hartmann  <mailto:j.l.h.hartmann at uva.nl>
<j.l.h.hartmann at uva.nl>@lists.osgeo.org 
Envoyé par : openlayers-users-bounces at lists.osgeo.org 


2012-03-07 10:27 


A
openlayers-users at lists.osgeo.org 	

cc

	

Objet
[Polluriel potentiel]  [OpenLayers-Users] force update markers layer	


	
	






Hi,

How do I force a redraw on a markers layer? I have a regular WMS map with
markers that have their lonlat-values updated from a database. I can force a
redraw of the WMS layer with mergenewparams(), but that is not possible with
the markers layer. That means that the when the lonlat values are updated
and I move the map, the markers remain in their original positions. Only
when I zoom in or out, the marker positions are updated. Can I do something
about that?

Jan_______________________________________________
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