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Chapter 16 Using HTML Forms

16.8 Server Side Image Maps 

In HTML, an element called 

MAP

 lets you associate URLs with various

regions of an image; then, when the image is clicked in one of the designated

regions, the browser loads the appropriate URL. This form of mapping is

known as a client side image map, since the determination of which URL to

contact is made on the client and no server side program is involved. HTML

also supports server side image maps that can be used within HTML forms.

With such maps, an image is drawn, and when the user clicks on it, the coor 

dinates of the click are sent to a server side program. 

Client side image maps are simpler and more efficient than server side

ones and should be used when all you want to do is associate a fixed set of

URLs with some predefined image regions. However, server side image

maps are appropriate if the URL needs to be computed (e.g,. for weather

maps), the regions change frequently, or other form data needs to be

included with the request. This section discusses two approaches to

server side image maps.

IMAGE Standard Server Side Image Maps

The usual way to create server side image maps is by means of an