Hello List,

at first i wanna thanks for the great work your team is doing. I really enjoy using OpenLayers and his nice features to create a good user experience. Right now i am building a sdi for a big amount of raster data. I publish the raster data via WMS (their access is right now restricted). At the client side i am using OpenLayers for displaying the data. This runs in most cases quite good. But sometimes and especially in Chromium i run in some timeout issues.

The Case:

OpenLayers try to send the WMS Request to server.

Request URL:

service_url?LAYERS=sachsen-default&TYPE=png&FORMAT=image%2Fpng&TRANSPARENT=true&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A900913&BBOX=1586191.7052772,6531373.4798253,1742734.7391834,6687916.5137316&WIDTH=256&HEIGHT=256

Request Headers:

Cache-Control: no-cache

Pragma: no-cache

Referer: http://localhost/client.html

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.22 (KHTML, like Gecko) Ubuntu Chromium/25.0.1364.160 Chrome/25.0.1364.160 Safari/537.22

Query String Parameters:

LAYERS: sachsen-default

TYPE: png

FORMAT: image/png

TRANSPARENT: true

SERVICE: WMS

VERSION: 1.1.1

REQUEST: GetMap

STYLES:

SRS: EPSG:900913

BBOX: 1586191.7052772,6531373.4798253,1742734.7391834,6687916.5137316

WIDTH: 256

HEIGHT: 256

This request seems to timeout than (server log: serverip - - [09/Jul/2013:19:58:24 +0200] "-" 408 0 "-" "-" ) and openlayers displays than pink tiles. I was able to handle this by setting up the OpenLayers parameter “OpenLayers.IMAGE_RELOAD_ATTEMPTS” to 5. After that modification OpenLayers is getting the map tiles through a new request-attempt after a timeout. This solution works, but it extremly slows down the hole application in cases of timeout issues.

This timeout issues appear consistently often in Chromium. In Firefox they seem to disappear. My question is now, if anybody knows this problem and if there exist a solution for it.

In case of question, here are some code snippets about my OpenLayers (Version: http://openlayers.org/api/OpenLayers.js) application:

var options = {

projection: new OpenLayers.Projection("EPSG:900913"),

displayProjection: new OpenLayers.Projection("EPSG:4326"),

units: "m",

maxResolution: 4891.9698093750003,

maxExtent: bounds,

controls: [

new OpenLayers.Control.Navigation(),

new OpenLayers.Control.LayerSwitcher(),

new OpenLayers.Control.PanZoomBar(),

new OpenLayers.Control.Attribution(),

new OpenLayers.Control.MousePosition(),

//new OpenLayers.Control.ScaleLine({geodesic:true})

]

};

map = new OpenLayers.Map('mapdiv', options);

 

layerSachsen_default = new OpenLayers.Layer.WMS("Sachsen (default)",

"wms_url",

{

layers: "sachsen-default",

type: "png",

format: "image/png",

transparent: 'true'

},{

isBaseLayer: false,

opacity: 0.85,

visibility: true

}

);

 

Kind regards,

JM

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