[OpenLayers-Users] [work] Re: OpenLayers Read From Text File

Mon Nov 26 20:55:47 EST 2007

Tara,

Sorry about emailing direct to Brad. I did CC Openlayers Users?

I use a xml file on the server. This could be generated via a database query
and formatted into XML but I just made mine in an editor.

I just use standard ajax to get the XML into the browser DOM. Once there,
you can build your own browser-side filters and present the data anyway you
like. In this example, I used the GoogleMaps API which is really no
different to an OL alternative with the exception that popups/infobubbles
are nicer in GM.

http://demo.cubewerx.com.au/bi_demo.html

Maybe this is of no help to you.

Anyway, I am thinking of integrating GoogleMaps markers inside OL until OL
markers and popus look better. That could be nice.

Cheers,

Brad Spencer

-----Original Message-----
From: Tara Athan [mailto:tara_athan at alt2is.com]
Sent: Tuesday, 27 November 2007 12:33 PM
To: Bradley McLain
Cc: Linda Rawson; bradleyspencer; OpenLayers Users
Subject: Re: [work] Re: [OpenLayers-Users] OpenLayers Read From Text File

There seems to be a missing message in this thread from Bradley Spencer,
perhaps sent directly to Bradley McLain, rather than the mailing list?  I
would be interested in his solution.
******
I have recently constructed such an implementation- it may be instructive
for you to hear what we have done.
The demo map appears at
http://alt2is.com/hcvMaps/latin1/html/hcvoppsmap_utf8.html
In this particular case, php is used to create the marker text file from a
database query.
{You can't see the php from the link above, of course but I am happy to
share code snippets if some one is interested.}
This presents the same information for all users.  The next step in our
implementation is to bring in the query capability.
Presently our map shows the number of all volunteer opportunities in each
country. We would like to allow the user to instead show that number of
opportunities that match their specifications- specialty field, duration
etc.- and have the link lead to a list of only these matches.
    This requires a database query when the user requests the map. Our plan
is to use a php file to query the database (also a
shadow database as you are considering, containing only information relevant
for the map, and synchronized with the main database regularly using cron
and a php script).
  If a text layer is used, then each user will be creating a unique text
file on the server, which is given some unique name  that is passed to the
html file by php. Some mechanism must be created to delete these files when
the user is done with them.
An alternative is to write marker information directly to the html file.
This has different options for the markers, including
> Markers with no pop-up, see
http://openlayers.org/dev/examples/markers.html
>Anchored bubbles, which offer the possibility of  changing the style of the
popup, which is not possible with the text layer:  see
http://dev.openlayers.org/docs/files/OpenLayers/Popup/AnchoredBubble-js.html
and http://openlayers.org/dev/examples/popups.html
However, based on the problems I see in this example, perhaps anchored
bubbles are not stable yet, or the example code has bugs...
I am debating which way to go and am interested in the experience of others-
Thanks
Tara
Bradley McLain wrote:
@ Linda I have been told that it would be preferable not to directly access
the information, they would prefer that the information is dumped nightly to
something else (text file or another database) and then accessed that way. I
thought that a text file would be the easier option, given the smaller size
and ease of maintenance.

@Brad, this sounds like the kinda of thing that I want to do. Doing it this
way will I be able to build some sort of interface that allows users to
search and display the markers that they want?

Cheers

Brad

On 27/11/2007, Linda Rawson < linda.rawson at gmail.com
<mailto:linda.rawson at gmail.com> > wrote:
Why don't you just create a database view of the information and make it
available via a web service and your users would always have up to date
information.

Linda
On Nov 26, 2007 3:12 PM, Julien-Samuel Lacroix < jlacroix at mapgears.com
<mailto:jlacroix at mapgears.com> > wrote:
Hi,

You have a great resource of examples here:
http://www.openlayers.org/dev/examples/

Check the markersTextLayer.html example to have an example of a layer
that comes from a csv file.
( http://www.openlayers.org/dev/examples/markersTextLayer.html
<http://www.openlayers.org/dev/examples/markersTextLayer.html> )

There's also use gml (see the gml-layer.html) if you prefer xml files.

Julien

Bradley McLain wrote:
> Ok what I am trying to do is to have a progress database dump all
> relevant information about various locations in some form of text file
> nightly.
>
> I then want to use OpenLayers to read from/query this file and display
> the relevant information.
>
> I was wondering if this is possible to do, can OpenLayers read/query a
> text file such as a csv or xml?
>
> Cheers
>
> Brad
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Users mailing list
> Users at openlayers.org <mailto:Users at openlayers.org>
> http://openlayers.org/mailman/listinfo/users

--
Julien-Samuel Lacroix
Mapgears
http://www.mapgears.com/
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Tara Athan

Principal, Alternatives to Invasive Species
tara_athan at alt2is.com <mailto:tara_athan at alt2is.com>
707-485-1198
PO Box 415
Redwood Valley, CA 95470
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