Wait for another file to execute before the caller continues to execute!!

Hello, I come across a difficulty when working on my project and I will appreciate if someone can help me push that botelneck away. Actually, I want a function callback midst in its file to pause and wait for another callback to provide it with data before it continues.

So that is how my code look like :

classdef user < handle
events
REPLY
REQUEST
end

methods
function obj= user

end

function AddListener(arg)
addlistener(arg,'REQEST',@(src,evnt)reply(obj,src,evnt));
addlistener(arg,'REPLY',@(src,evnt)request(obj,src,evnt));

end 

function reply(obj,src,evnt)

step1
step2
notify(obj,'REPLY',eventData(sendingdata));

end

function request(obj,varargin)
step1
step2
notify(obj,'REQUEST');
for i=1:(4/0.1)
pause(0.1);
end % end for loop
step3
step4
end
end %end methods block
end %end class

the class user defines object which exchange data interactively. We create two objects

user1 = user; and user2=user; add listener to each other by

user1.AddListener(user2);
user2.AddListener(user1);

Then we start the proces by

user1.request();

instead of waiting reply-callback from user2, request from user1 run to the end.

What can i do to eleviate that issue?

thanks for your help!

Bolivar