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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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)

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