performance vs. design

Christoph Baudson christoph.baudson at
Fri Nov 10 04:58:19 EST 2006

Hi there,

the worst problem while redesigning the digitizing/WFS components was 
how to keep Mapbender lean and not overloading map.php with too much 
content. A very basic Mapbender should load as fast as possible.

One example: We have a new function that calculates the part of a line 
which actually lies within the mapframe. With this, we don't have to 
paint parts of geometries we don't see at all. That enhances the 
performance a lot. The problem is: this function should be (speaking in 
terms of OO-design) a method of the map object class. You ask the map 
object (f.e. mapframe1) which part of a geometry it contains. But adding 
these function(s) to the map object class would result in more size and 
more traffic.

The solution now is to ask the map object about its width/height (that 
always includes getting the map object index by the frame name first) 
and then call a geometry function that determines which part of a 
geometry lies within a box with given width and height. Not as 
beautiful, but maybe more efficient.

This is just one example, there are dozens more.

So there is a trade-off between performance and software design. Maybe 
other developers might share their insights about this.



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