Layers in OpenLayers

OpenLayers is a JavaScript framework, and as discussed earlier is built using Object Oriented Programming. When we want to actually create a layer, we create (or instantiate) an object from an OpenLayers Layer class.

OpenLayers has many different Layer classes, each allowing you to connect to a different type of map server 'back end.' For example, if you wanted to connect to a WMS map server, you would use the Layer.WMS class, and if you wanted to use Google Maps you'd use the Layer.Google class. Each layer object is independent of other layer objects, so doing things to one layer won't necessarily affect the other.

Note

How many layers can I have?

The safest maximum amount of layers you can have on a map at one time depends largely on the user's machine (i.e., their processing power and memory). Too many layers can also overwhelm users; many popular web maps (e.g., Googl\e and Yahoo!) contain just a few layers. If you need to use tons of layers (say, more than fifty), it...