osmWebWizard OpenLayers HTTP/HTTPS redirects refused by the map server

[jprk]

Since some time ago I was experiencing problems running osmWebWizard in Chrome: The whole app started but it did not display any map tiles, all images were shown as inaccessible. Today I had a look using the developer mode and the console is full of the following error messages:

Redirect from 'http://b.tile.openstreetmap.org/16/35207/21492.png' to 'https://b.tile.openstreetmap.org/16/35207/21492.png' has been blocked by CORS policy: The 'Access-Control-Allow-Origin' header has a value 'null' that is not equal to the supplied origin. Origin 'null' is therefore not allowed access.

CORS stands for Cross-Origin Resource Sharing and it seems that the tile server will not honour the redirect of http://... to https://... if the origin is not server by a server but it is coming from a file (the wizard page is displayed using file://...).

I have solved it by using the approach described in this StackExchange discussion, i.e. changing the code at

https://github.com/eclipse/sumo/blob/5b91df43ebe956661769e903b2da8f83e7665f60/tools/webWizard/script.js#L236

to

    // OSM map
    var map = new OpenLayers.Map("map");
    var maplayer = new OpenLayers.Layer.OSM(
    "OpenStreetMap", 
    // Official OSM tileset as forced HTTPS URLs
    [
        'https://a.tile.openstreetmap.org/${z}/${x}/${y}.png',
        'https://b.tile.openstreetmap.org/${z}/${x}/${y}.png',
        'https://c.tile.openstreetmap.org/${z}/${x}/${y}.png'
    ], 
    null);
    map.addLayer(maplayer);

I do not know yet if this is Windows/Chrome specific.

Jan

[namdre]

Thanks Jan!