def call(env)
      @request = Rack::Request.new(env)
      xml_response = @xmlrpc_handler.process(request_body)
      [200, {'Content-Type' => 'text/xml'}, [xml_response]]
    end
def call(env)
      @request = Rack::Request.new(env)
      xml_response = @xmlrpc_handler.process(request_body)
      [200, {'Content-Type' => 'text/xml'}, [xml_response]]
    end
A new instance of Server.
 @param [Proc, #call] request_handler proc which implements the pingback registration and takes the source_uri and the target_uri
     as params. Use the exceptions defined in Pingback to indicate errors.