[OpenLayers-Users] Users Digest, Vol 47, Issue 35
Hubick, William
William.Hubick at cobham.com
Tue Aug 10 14:01:21 EDT 2010
Hi Everyone,
Thanks for the quick replies. Much appreciated.
To be clear, my primary question is about efficiency. Optimally, I would like OpenLayers to check a GeoRSS XML file very regularly (e.g., every 30 seconds). If the file has an <updated> element with a date/time since the last update, OpenLayers would refresh the layer. However, it would seem like a GeoRSS-friendly application would update a layer rather than destroy and reload it. For example, if only one item was added since the previous load, OpenLayers should only have to load that item. Reloading the entire layer each time seems inefficient to me, and not fully in the spirit of RSS. This seems especially so in the case of a large XML file with many points, and when the data is being pulled from remote servers.
Does that make sense? Is the destroy/reload-style refresh the only option for GeoRSS?
Thanks again!
Bill
Bill Hubick
william.hubick at cobham.com
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From: users-request at openlayers.org
Sent: Tue 8/10/2010 1:23 PM
To: users at openlayers.org
Subject: Users Digest, Vol 47, Issue 35
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Today's Topics:
1. Re: Add custom control, possible? (Planet)x)
2. Re: Add custom control, possible? (Planet)x)
3. Auto-refreshing a GeoRSS layer (Hubick, William)
4. Re: Auto-refreshing a GeoRSS layer (Bart van den Eijnden)
5. Re: Auto-refreshing a GeoRSS layer (Alexandre Dube)
6. Re: RE wmsGetFeatureInfo with Mapserver (Bennos)
7. Re: Auto-refreshing a GeoRSS layer (christopher.schmidt at nokia.com)
----------------------------------------------------------------------
Message: 1
Date: Tue, 10 Aug 2010 09:26:33 -0700 (PDT)
From: "Planet)x" <andrew.stewart at reddeer.ca>
Subject: Re: [OpenLayers-Users] Add custom control, possible?
To: users at openlayers.org
Message-ID: <1281457593675-5393782.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii
Sorry I figured out how to add a custom control by using the Button control
and creating a function to run when the button is clicked. My next question
is how do I change the icon image of the button if I want to have 2 or more
custom buttons? i was able to change the icon of one by using the following
code but it is the same for each button, I need different icons for each.
Thanks for advice.
.olControlPanel .olControlButtonItemActive {
background-color: blue;
background-image:
url("OpenLayers-2.9.1/theme/default/img/pan_on.png");
}
.olControlPanel .olControlButtonItemInActive {
background-color: orange;
background-image:
url("OpenLayers-2.9.1/theme/default/img/pan_off.png");
var btn = new OpenLayers.Control.Button({trigger: onTrigger});
--
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------------------------------
Message: 2
Date: Tue, 10 Aug 2010 09:51:15 -0700 (PDT)
From: "Planet)x" <andrew.stewart at reddeer.ca>
Subject: Re: [OpenLayers-Users] Add custom control, possible?
To: users at openlayers.org
Message-ID: <1281459075486-5393884.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii
Ok I was also able to figure this out -
for the CSS style I did this
.olControlPanel .olControlButtonHomeItemActive {
background-image:
url("OpenLayers-2.9.1/theme/default/img/home.gif");
}
.olControlPanel .olControlButtonHomeItemInActive {
background-image:
url("OpenLayers-2.9.1/theme/default/img/home.gif");
and for my button I did this -
var btn = new OpenLayers.Control.Button({trigger: onTrigger, title: "Reload
Website", displayClass: 'olControlButtonHome'});
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------------------------------
Message: 3
Date: Tue, 10 Aug 2010 13:05:27 -0400
From: "Hubick, William" <William.Hubick at cobham.com>
Subject: [OpenLayers-Users] Auto-refreshing a GeoRSS layer
To: "users at openlayers.org" <users at openlayers.org>
Message-ID: <D2126A4C-774E-4229-A6B5-3FFF746AE7FF at mimectl>
Content-Type: text/plain; charset="iso-8859-1"
Hi Everyone,
My project is considering GeoRSS as our data-sharing standard with partners. I am pleased with how easily OpenLayers will display GeoRSS points, but I'm wondering how other developers ensure efficient auto-updates. My first impression was that OpenLayers would automatically check a GeoRSS XML file and automatically load updates (i.e., like an RSS aggregator). When further exploring, it seems like custom code must be written to auto-update the layer.
Am I missing something? Is there a way to ensure new points added to a GeoRSS file are automatically, efficiently loaded by OpenLayers (without page refresh)? It seems like there must be a better way to update the layer than destroying and reloading the GeoRSS layer.
Any help would be greatly appreciated!
Thanks in advance,
Bill
Bill Hubick
Cobham Analytic Solutions
william.hubick at cobham.com
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Message: 4
Date: Tue, 10 Aug 2010 19:13:58 +0200
From: Bart van den Eijnden <bartvde at osgis.nl>
Subject: Re: [OpenLayers-Users] Auto-refreshing a GeoRSS layer
To: "Hubick, William" <William.Hubick at cobham.com>
Cc: "users at openlayers.org" <users at openlayers.org>
Message-ID: <F7C78F72-834B-47C3-9448-73C100D8C538 at osgis.nl>
Content-Type: text/plain; charset="us-ascii"
I would use a vector layer with a http protocol pointing to the GeoRSS file, and then add a Refresh Strategy.
Something like this (untested, for a refresh every 60 seconds):
var layer = new OpenLayers.Layer.Vector("mylayer", {
strategies: [new OpenLayers.Strategy.Fixed(), new OpenLayers.Strategy.Refresh({interval: 60000})],
protocol: new OpenLayers.Protocol.HTTP({
url: "http://myhost/mygeorss",
format: new OpenLayers.Format.GeoRSS()
});
Best regards,
Bart
--
Looking for flexible support on OpenLayers or GeoExt? Please check out http://www.osgis.nl/support.html
Bart van den Eijnden
OSGIS
bartvde at osgis.nl
On Aug 10, 2010, at 7:05 PM, Hubick, William wrote:
> Hi Everyone,
>
> My project is considering GeoRSS as our data-sharing standard with partners. I am pleased with how easily OpenLayers will display GeoRSS points, but I'm wondering how other developers ensure efficient auto-updates. My first impression was that OpenLayers would automatically check a GeoRSS XML file and automatically load updates (i.e., like an RSS aggregator). When further exploring, it seems like custom code must be written to auto-update the layer.
>
> Am I missing something? Is there a way to ensure new points added to a GeoRSS file are automatically, efficiently loaded by OpenLayers (without page refresh)? It seems like there must be a better way to update the layer than destroying and reloading the GeoRSS layer.
>
> Any help would be greatly appreciated!
>
> Thanks in advance,
>
> Bill
>
> Bill Hubick
> Cobham Analytic Solutions
> william.hubick at cobham.com
>
> Please consider the environment before printing this email
>
> _______________________________________________
> Users mailing list
> Users at openlayers.org
> http://openlayers.org/mailman/listinfo/users
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Message: 5
Date: Tue, 10 Aug 2010 13:14:19 -0400
From: Alexandre Dube <adube at mapgears.com>
Subject: Re: [OpenLayers-Users] Auto-refreshing a GeoRSS layer
To: users at openlayers.org
Message-ID: <4C6188EB.7080400 at mapgears.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi Bill,
I never used it, but it would seem that the 'Refresh' Strategy could
do the trick for you.
Regards,
Alexandre
On 10-08-10 01:05 PM, Hubick, William wrote:
> Hi Everyone,
> My project is considering GeoRSS as our data-sharing standard with
> partners. I am pleased with how easily OpenLayers will display GeoRSS
> points, but I'm wondering how other developers ensure efficient
> auto-updates. My first impression was that OpenLayers would
> automatically check a GeoRSS XML file and automatically load updates
> (i.e., like an RSS aggregator). When further exploring, it seems like
> custom code must be written to auto-update the layer.
> Am I missing something? Is there a way to ensure new points added to a
> GeoRSS file are automatically, efficiently loaded by OpenLayers
> (without page refresh)? It seems like there must be a better way to
> update the layer than destroying and reloading the GeoRSS layer.
> Any help would be greatly appreciated!
> Thanks in advance,
> Bill
> *Bill Hubick*
> Cobham Analytic Solutions
> william.hubick at cobham.com <mailto:william.hubick at cobham.com>
> *Please consider the environment before printing this email*
>
>
> _______________________________________________
> Users mailing list
> Users at openlayers.org
> http://openlayers.org/mailman/listinfo/users
>
--
Alexandre Dub?
Mapgears
www.mapgears.com
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Message: 6
Date: Tue, 10 Aug 2010 10:15:14 -0700 (PDT)
From: Bennos <benjaminpreisig at gmx.at>
Subject: Re: [OpenLayers-Users] RE wmsGetFeatureInfo with Mapserver
To: users at openlayers.org
Message-ID: <1281460514970-5393989.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii
Hi,
Steve, thank you! The logs didnt help, but the link to the other
implementation of the GetFeatureInfo.
My mistake was, that i used an OpenLayers.Layer.MapServer instead of an
OpenLayers.Layer.WMS ... so it couldnt work. I also added the highlightLayer
from the example- i dont know exactly what its purpose is - just to be sure.
Cheers,
Benjamin
--
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------------------------------
Message: 7
Date: Tue, 10 Aug 2010 19:22:52 +0200
From: <christopher.schmidt at nokia.com>
Subject: Re: [OpenLayers-Users] Auto-refreshing a GeoRSS layer
To: <William.Hubick at cobham.com>
Cc: users at openlayers.org
Message-ID: <A993A915-23D8-44B0-8D72-36936749EBDD at nokia.com>
Content-Type: text/plain; charset="us-ascii"
On Aug 10, 2010, at 1:05 PM, ext Hubick, William wrote:
> Hi Everyone,
>
> My project is considering GeoRSS as our data-sharing standard with partners. I am pleased with how easily OpenLayers will display GeoRSS points, but I'm wondering how other developers ensure efficient auto-updates. My first impression was that OpenLayers would automatically check a GeoRSS XML file and automatically load updates (i.e., like an RSS aggregator). When further exploring, it seems like custom code must be written to auto-update the layer.
>
> Am I missing something? Is there a way to ensure new points added to a GeoRSS file are automatically, efficiently loaded by OpenLayers (without page refresh)? It seems like there must be a better way to update the layer than destroying and reloading the GeoRSS layer.
In general, RSS feeds are not updated in 'realtime' -- there
is no way that an RSS feed can 'push' data to the client consuming
it.
Using an OpenLayers.Layer.Vector, with a Protocol.HTTP, and a
Strategy.Refresh, which has:
* Property: interval
* {Number} Auto-refresh. Default is 0. If > 0, layer will be refreshed
* every N milliseconds.
*/
interval: 0,
would allow you to tell OpenLayers to re-load the GeoRSS file
from the server every $interval milliseconds.
This doesn't solve the need to have real-time updates, but it allows
you to implement a refresh without a page reload.
-- Chris
> Any help would be greatly appreciated!
>
> Thanks in advance,
>
> Bill
>
> Bill Hubick
> Cobham Analytic Solutions
> william.hubick at cobham.com
>
> Please consider the environment before printing this email
>
> <ATT00001..txt>
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