Suppose you are going to design an instant messaging application called Telegraph. Telegraph is a modularized application composed of UI module, Chat module, and Contact module. The UI module uses the...

Extracted text: Suppose you are going to design an instant messaging application called Telegraph. Telegraph is a modularized application composed of UI module, Chat module, and Contact module. The UI module uses the Chat module and the Contact module to render the user interface. The Chat module deals with sending and receiving messages. The Chat module uses the Network module for network communication. When users send/receive messages via the network, the Chat module uses the Crypto module to encrypt/decrypt the message. The Contact module manages the contact list. It also uses the Crypto module for encryption/decryption. The Crypto module uses the Math module for calculation. Now we propose a metric to measure the stability of modules. Formally, we define the "stability" of a module i as Si = a+dut where di" (i.e., incoming connection or dependency) is the number of modules that directly or indirectly USES module i and d?ut (i.e., outgoing connection or dependency) is the number of modules that module i directly or indirectly USES. For example, Figure 2-1 shows module X, that is used by three modules, so d = 3 and dout = 0. Thus, module x should be unlikely to change because it has three incoming dependencies. Conversely, in Figure 2-2, module Y uses three modules, i.e., dgut = 3, so it is more likely to change due its three outgoing dependencies. If a USES b and b USES c, then din = 2. USES USES USES module X Figure 2-1: Three modules USES module X module Y USES USES USES Figure 2-2: Module Y USES three modules


Extracted text: (2) Draw the IS COMPONENT OF relation and the USES relation among the modules whose names are identified.