[OpenLayers-Users] Move to Openlayers

Peesjee openlayers at tauris.be
Wed Jan 7 08:53:03 EST 2009


Thx Till, 

your answer clears a lot of questions for me. I am definitely a *newbie* in
this area. I started reading about WMS and WFS yesterday, i even installed
'GeoServer', and succesfully mapped custom shapefile into the Geoserver. But
then i got stuck thinking that only OpenLayers was responsible for the
objects on the Map. I read about WFS, but i thought that was for retrieving
data from existing data in maps (which my ships are not). I was clearly
wrong.

So can i say that: with GeoServer i must be able to show my own "maps" (tiff
images), include the ships positions (with WFS) from our database...return
this as one WMS layer... and add this layer in with Openlayers.

I have to figure the WFS part of the puzzle then...

ps: seeing your answer and mine now, this post doesn't handle much of
openlayer, sorry for that...

Greetz
Peesjee





Till Adams wrote:
> 
> Hi,
> 
> it is a WMS or WFS solution - that is what I probably would think as 
> well:: There is a probalby UMN Mapserver or Geoserver (as WMS servers)  
> solution behind, which handles the points (your ships) out of the 
> database or a file. For this case, OL only has to handle one image, 
> regardless whether you have 1, 3 or 2000 ships - this is a matter of the 
> database or file feeding the WMS server behind, not of the client to 
> render every single point.
> 
> To explain the rough archtitecture behind - there is a WMS server like 
> UMN or Geoserver (see www.osgeo.org for more info on them), they access 
> your ship data (don't know where they come out, file or database?), you 
> give them a marker and they create an image on the fly out of the ships 
> - a WMS map request looks like that:
> 
> http://www.webmapcenter.de/cgi-bin/mapserv?map=/var/data/www.webmapcenter.de%2Fnabu%2Fportale.map&TRANSPARENT=true&LAYERS=portale&FORMAT=image%2Fpng&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&SRS=EPSG%3A900913&BBOX=761809.6422981643,6579508.301301379,831099.8084290314,6616771.352585221&WIDTH=1813&HEIGHT=975
> 
> As you can see, there is are params like BoundingBox, layer, coordinate 
> system (srid) and so on - they let you control the "place" (don't find a 
> better word) you see on the map. The configuration of our WMS let you 
> control the rendering of the images, e.g. different symbols and/or sizes 
> based on any attribute(s).
> The WMS server parses the request, accesses the data (your ships), 
> creates a png (or gif, jpeg, ...) and sends it back to the requesting 
> client.
> More: see http://en.wikipedia.org/wiki/Web_Map_Service
> 
> The request as above is directly taken from OL, so you only have to care 
> about the WMS, not the rest, this will be done by OL for you.
> 
> In the OL main file you bring the things together, the base layer from 
> google and the WMS from your server - that's it, no worry about the 
> amount of ships.
> 
> BTW: I give you another strong reason why switching to openlayers makes 
> sense: By changing one line of code you may switch from google basemaps 
> to yahoo, virtual earth or any other base map service supported by OL, 
> if any reason to do this comes up. Using the google API means using 
> google maps ;-)
> 
> Kind regards - Till
> 
>> Hi,
>>
>> Let me explain my situation. I recently created an website showing
>> current
>> positions of ships with googlemaps. For a couple of reasons, we want to
>> migrate to another solution. One of the reasons is performance. With
>> googlemaps, i parse an xml (given by a webservice) and add/update markers
>> for every ship to show. This slows down with the number of ships to show
>> (example, sometimes we show more than 500 ships). To be honest, i'm not
>> sure
>> this is a good way to work...
>>
>> We are in contact with a company that offers a solution for us. They use
>> Openlayers. We have seen a demo and its very fast. I dont think they add
>> "markers" for every ship. Cause, when i zoom, the object also zooms, and
>> then refresh to the correct size it was before. How do they do that? Its
>> extremely fast, less than a second to show a 1000 of objects on a map.
>>
>> i'm given the task to investigate the possibilities of Openlayers, and
>> decide whether we can implement everything ourselfs (with openlayers), or
>> just buy the solution of that company. i'm afraid that, with my
>> "solution",
>> adding so many markers, the website would'nt be that fast.
>>
>> What is the best way to put 500 - 1000 "markers" on a map? (and refresh,
>> when refreshing in googlemaps, i had to update the marker-objects to
>> prevent
>> flickering) Sometimes a have to draw lines between them (tracking). (i
>> know
>> of the image caching problem in IE)
>>
>> I see i can add Markers, GML, geoRSS. So, which one do i use? i could
>> create
>> a webservice that gives me a GML, so i only have to load it, but is this
>> fast? or do i use my googlemaps way, adding markers and updating those
>> markers (slow)?
>>
>> Greetz
>> Peesjee
>>
>>
>>   
> 
> 
> -- 
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> 
> Till Adams
> Geschäftsführung
> 
> Tel: +49 (0)228 / 962 899-52
> Fax: +49 (0)228 / 962 899-57
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> Amtsgericht Bonn, HRA 6835
> ---------------------------------------------------------
> 
> Komplementärin:
> 
> terrestris Verwaltungs GmbH
> 
> vertreten durch:
> Hinrich Paulsen, Till Adams
> 
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