[OpenLayers-Users] Move to Openlayers

[Till Adams]

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
>
>
>   


-- 
----------------------------------------------------------
terrestris GmbH & Co. KG
Irmintrudisstrasse 17
53111 Bonn
Germany

Till Adams
Geschäftsführung

Tel: +49 (0)228 / 962 899-52
Fax: +49 (0)228 / 962 899-57
adams at terrestris.de http://www.terrestris.de
Amtsgericht Bonn, HRA 6835
---------------------------------------------------------

Komplementärin:

terrestris Verwaltungs GmbH

vertreten durch:
Hinrich Paulsen, Till Adams