Page 82 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Object Oriented Analysis and Design

Notes 13. A .................. is used when many transitions lead to a certain state.
14. State may be divided into regions containing .................. that exist and execute concurrently.
15. .................. from one state to the next are denoted by lines with arrowheads.

Case Study State Diagram for Telephone Line

Consider the class for telephone line with following activities and states

As a start of a call, the telephone line is idle. When the phone receiver is picked from
hook, it gives a dial tone and can accept the dialing of digits.
If after getting dial tone, if the user doesn’t dial number within time interval then
time out occurs and phone line gets idle.
After dialing a number, if the number is invalid then some recorded message is
played.

Upon entry of a valid number, the phone system tries to connect a call & routes it to
proper destination.
If the called person answers the phone, the conversation can occur. When called
person hangs up, the phone disconnects and goes to idle state.
Draw the state transition diagram for above description of telephone line.

Figure 1: State Transition Diagram of Telephone Line

Question
Explain the use case relationships used in the state transition diagram of telephone line.
Source: http://www.programsformca.com/2012/03/state-diagram-for-telephone-line.html

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