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

[Bartłomiej Burkot]

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 <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_______________________________________________
>> Users mailing list
>> Users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>
>>
>>
>
>
> _______________________________________________
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