CH 13 APPLICATION ANALYSIS

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Collin Chapman
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1 CH 13 APPLICATION ANALYSIS

2 APPLICATION INTERACTION MODEL Steps: Determine system boundary Find actors Find use case Find initial & final events Prepare a normal scenario Add exception scenario Prepare activity diagrams for complex use case Organize actors & use case Check against domain class model

3 Determine system boundary Understand scope / boundary of system in order to specify functionality. Decide what system includes & what it eliminating If system boundary is drawn correctly you can regard system as single object, whose internal details are hidden & changeable ATM ex:-design a s/w to support banking network including human cashier & ATM.from customer perspective both are method of conducting business has same effect on a bank account but in commercial practice ATM application would be separate from cashier

4 Find actors Identify the external objects that interact directly with the system. these are its actors Actors include humans, external devices & other s/w systems Each actor represents an idealized user that exercises some subset of system functionality Examine each actor to see if it has several distinct faces ATM EX:- A person can be bank teller & customer of same bank A person approaches the bank in one or other role at a time. ATM actors are Customers, Bank & Consortium

5 Find use case For each actor list different ways in which it uses system Use case partitions functionality of system into small no. of discrete units. Keep all of use case at a similar level of detail EX:-if 1 use casein bank is apply for loan then another use case should not be withdraw cash from savings account using ATM Associate actors & use case that initiate it, but other actors may involved as well

6 ATM intiate session query account Bank Customer process transaction transmit data Consortium

7 Find initial & final events You must understand execution sequences that cover each use case. start by finding the event that initiate each use case. Determine which actor initiate it Initial event is occurrence that triggers a chain of activity. Determine final event Ex:-use case for applying loan final event can be application is submitted, until loan is granted or rejected, until money from loan is delivered or until loan is finally paid off & closed

8 Prepare a normal scenario For each use case prepare one or more system behavior Scenario illustrate major interactions, external display formats & information exchange. Sometime problem statement describe full interaction but most of time you will have to invent interaction Prepare a scenario for normal cases without unusual inputs or error

9 Initiate session: ATM asks user to insert card User insert a card ATM accepts card & reads its serial number ATM request password User enters password ATM verifies password by contracting consortium & bank ATM displays a menu of a/c & commands. User choose command to terminate session ATM prints a receipt,eject card & ask user to take them

10 Add exception scenario Consider special cases such as omitted input, maximum & minimum values & repeated values Consider error cases, including invalid values & failure to respond ATM ex:- some variations & exception follows ATM cant read the card Card is expired ATM time out waiting for a response Amount is invalid Machine is out of cash or paper

11 Prepare activity diagrams for complex use case Sequence diagram capture interplay between actors but they do not show alternative & decisions Ex:- you need one sequence diagram for main flow of interaction & additional sequence diagram for each error & decision point Activity diagram consolidate all this behavior by forks & merges in control flow

12 insert card Return Card [communication down ] [readable ] [communication down ] [card OK] [good account ] [unreadable ] [bad bank code ] [account fraud alert ] [communication down ] Request password [communication down ] [multiple password failure ] [correct password ] Keep card

13 Application & domain classes should be consistence. Actors, use case & scenario are all based on classes & concepts from domain model Cross check these models to ensure that they are no inconsistencies. Examine scenario & make sure that it has all necessary data Organize actors & use case Organize use cases with include ; extend & generalization relationships This is helpful for large & complex system ATM EX:-initiate session includes query account & process transaction Check against domain class model

14 APPLICATION STATE MODEL First identify classes with multiple states & use interaction model to find events for these classes. Construct application state model using following steps Determine application classes with state Find events Build state diagram Check against other class & interaction model

15 Determine application classes with state Application class model adds computer oriented classes. Consider each application class which one have multiple state User interface classes & controller classes are good classes for state model

Requirements document for an automated teller machine. network

Requirements document for an automated teller machine network August 5, 1996 Contents 1 Introduction 2 1.1 Purpose : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.2 Scope