[OpenLayers-Dev] Creating custom 3rd party Layers

[Andrea Battisti]

Hi all,

I recently very much appreciated the OL's ability to connect to and 
display different kind of layers on a web page.

I was wondering how difficult is to extend it to make use of third party 
geospatial data and protocols.
I took a quick look at some of the 3rd party implementations (i.e. the 
WMS and Google classes ...) but what I miss is the general understanding 
of the whole process of requesting tiles, and the "behind the scenes" 
working of the Layer class and subclasses.
(i.e. I didn't find in the WMS implementation (WMS.js) where the actual 
GetMap request is built and performed.)

First of all, what is the base class to inherit from, in order to create 
a custom layer?
I guess it is OpenLayers.Layer.EventPane as it is written in the doc, 
but is there a simple example to start with?

Basically for each tile I have to build a formatted request string 
specifying the spatial bounds, projection and some options, submit the 
request using http, reading and parsing the reply and extracting from it 
an url pointing to the actual image data to be displayed.


Thanks in advance!
Best,

-- 
Andrea Battisti
Applied Coherent Technology Corp.