[OpenLayers-Users] Showing points from a database

Fri Sep 19 14:11:06 PDT 2014

Thank you very much for your answer. I have therefore started to
investigate the possiblity to use the GeoJSON format, and now I am trying
to train with this format with this example but it doesn't work

    <script type="text/javascript">

    var map = new OpenLayers.Map("my_map");

    var layer = new OpenLayers.Layer.OSM("OpenStreetMap");
    map.addLayer(layer);

    map.addControl(new OpenLayers.Control.LayerSwitcher());
    map.setCenter(new OpenLayers.LonLat(0,0), 2);

    var citiesLayer = new OpenLayers.Layer.Vector("World Cities (GeoJSON)",
        {   protocol: new OpenLayers.Protocol.HTTP({
            url: "http://localhost/openlayers/world_cities.json",
            format: new OpenLayers.Format.GeoJSON()
        }),
        strategies: [
            new OpenLayers.Strategy.Fixed(),
            new OpenLayers.Strategy.Cluster({distance: 15})
        ]
    });
    map.addLayer(citiesLayer);
</script>

In order to make the protocol work I have installed nginx on my laptop and
the url correctly points to the file world_cities.json in my browser.
Anyway this example doesn't work, any idea why?

Thanks!
Niccolò

2014-09-19 15:54 GMT+02:00 Mark Prins <mc.prins at gmail.com>:

> using plain text or (geo) json is much less error prone than using
> GML, and probably gives better performance
>
> 2014-09-19 15:45 GMT+02:00 Niccolò Dal Santo <ncl.dalsanto at gmail.com>:
> > Hi there,
> >
> > I am new of Openlayers and I need to show some points that come from a
> > database on a map centred in Turin (Italy), with some information
> related to
> > this point (for instance an image). Searching on line I have found that
> > Openlayers supports many formats of data like GML, KML, GeoJSON and many
> > others. Could you suggest a format useful fror my problem and maybe some
> > examples of how to use it?
> >
> > I have tried with this code generating a map of europe, but it doesn't
> work
> >
> > <html>
> > <head>
> >   <title>Prova GML</title>
> >     <script src="http://openlayers.org/api/OpenLayers.js"></script>
> > </head>
> >     <body>
> >     <div id="ch3_gml" style="width: 100%; height: 100%;"></div>
> >
> >     <script type="text/javascript">
> >
> >         // Create the map using the specified DOM element
> >         var map = new OpenLayers.Map("ch3_gml");
> >
> >         var layer = new OpenLayers.Layer.OSM("OpenStreetMap");
> >         map.addLayer(layer);
> >
> >         map.addControl(new OpenLayers.Control.LayerSwitcher());
> >         map.setCenter(new OpenLayers.LonLat(0,0), 2);
> >
> >         map.addLayer(new OpenLayers.Layer.Vector("Europe (GML)", {
> >             protocol: new OpenLayers.Protocol.HTTP({
> >                 url: "./europe.gml",
> >                 format: new OpenLayers.Format.GML()
> >             }),
> >             strategies: [new OpenLayers.Strategy.Fixed()]
> >         }));
> >     </script>
> > </body>
> > </html>
> >
> > where europe.gml is a gml file in the same folder of this script, but
> > nothing happens.
> >
> > Thank you very much for your help!
> >
> > Regards
> >
> > Niccolò
> >
> > --
> > Niccolò Dal Santo
> > +39 342 15 70 842
> > ncl.dalsanto at gmail.com
> >
> > _______________________________________________
> > Users mailing list
> > Users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/openlayers-users
>
>
>
> --
> Disclaimer;
> This message is just a reflection of what I thought at the time of
> sending. The message may contain information that is not intended for
> you or that you don't understand.
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-- 
Niccolò Dal Santo
+39 342 15 70 842
ncl.dalsanto at gmail.com
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