process request,

def _request_cb(self, env, start_response):
        """process request, 
        """
        if env['REQUEST_METHOD'] == 'GET':
            return self._handle_GET(env, start_response)

        if env['REQUEST_METHOD'] == 'POST':
            return self._handle_POST(env, start_response)
            
        start_response("500 ERROR", [('Content-Type','text/plain')])
        s = StringIO()
        h = env.items(); h.sort()
        for k,v in h:
            print >>s, k,'=',`v`
        return [s.getvalue()]