about the absolutely path

I have a php application (let's call it app A) which is developed separated in a test domain name, like http://testa.xxx.com <http://testa.xxx.com/> /. But now I have to move it to another app (called B) using http://testb.xxx.com <http://testb.xxx.com/> /, and the app A becomes just a subsystem of app B. The access url is changed to http://testb.xxx.com/a/. Then I meet a problem that the app A 's links, the path and other elements in it are set like '/Main.php', '/art/logo.gif' by an absolutely path. The app A is very independent and I do not want to disperse it to app B. So how can I get this effect: when the user input the url, ' http://testb.xxx.com/a/ ', the app A will work fine? Can I just modify some configuration about yapache to fit this requirement? Best regards, Yang Shiqi