anu comp2110 software design lecture 5 comp2110 software design in 2003 lecture 5 requirements...

ANU comp2110 Software Design lecture 5

COMP2110 Software Design in 2003 lecture 5 Requirements Specifications lecture 3 of 3

The Encounter game case study0. introduction to the Problem – the Encounter Game1. examples from the specification document


The Software Requirements Specification SRS

The product of the Analysis phase isa well defined information model:• a set of labelled, organised requirements statements:

• functional consumer and developer requirements • system requirements• performance requirements

• a set of use cases or scenariosthat capture and express the relationships between the model and the real world of the problem

• other explanatory models:• interfaces, states, decisions


A Case Study of Encounter: Overview (1)

An overview of the Specification of the Encounter video gameSpecification document comes in 2 parts: http://cs.anu.edu.au/student/comp2110/resources/ Encounter-SRS/EncounterSRS-1.htmland ...

EncounterSRS-1.html

you need to study this to prepare for tutorial in week 3


A Case Study of Encounter: Overview (2)

The Encounter game is• a computer based role playing game which simulates all or part of

the lifetime of the player’s character• includes characters not under player’s control, called foreign

chacters• game characters have a number of qualities: strength, speed,

patience etc• each quality has a numerical values• the game is played over a map of areas (rooms)• characters engage each other when in the same area• the result of an engagement depends on the area and the values of

the qualities of the two characters• success is measured by living as long as possible with accumulated

points


Sample Encounter Screen

dressing room

kitchen

living room

COURTYARD

Set qualities

End game

Get status

Graphics reproduced with permission from Corel.

Adapted from Software Engineering: An Object-Oriented Perspective by Eric J. Braude (Wiley 2001), with permission.


User Interface for Setting Quality Values

Shawn

Choose the quality you wish to set

16.3

Current life points: 100.0

Choose the value of the quality selected

image



User Interface for Setting Quality

Values

The values of the qualities not specifically chosen remain in the same proportion to each other. Values less than 1.0 are counted as zero. E.g.,

before: strength = 10.0, endurance = 60.0, intelligence = 30.0, patience = 0.0

(current life points 10.0 + 60.0 + 30.0 + 0 = 100.0)

change: strength from 10.0 to 20.0

after: strength = 20, endurance = 53.33, intelligence = 26.66

16.3

Current life points: 100.0

ImageChoose the quality you wish to set

Choose the value of the quality selected

Explanation

Shawn

OKGraphics reproduced with permission from Corel.Adapted from Software Engineering: An Object-Oriented Perspective by Eric J. Braude (Wiley 2001), with permission.


2. Player requests a window for setting his character’s qualities.


Engage Foreign Character Use Case

Encounter

player

1. System displays the foreign character in the same area as the player’s.

2. System exchanges data between the two characters.3. System displays the results of the engagement in a message window. 4. Player dismisses window.

Initialize

. . . .

Engageforeign

character

Name of use case

Details of use case

Actor (agency external to the application)



A use case expressed in text

2.2.3 "Engage Foreign character" use caseActor: player of Encounter1. System displays the foreign character into the same area as the player

2. System exchanges data between the two characters

3. System displays the results of the engagement in a message window. 4. Player dismisses window.


A use case expressed in text

2.2.3 "Engage Encounter Foreign character" use case

Actor: player of Encounter

1. System displays the moves a foreign character into the same area as area occupied by the playeror Player moves into the area containing a foreign character.

2. System exchanges data between the two characters causes the two characters to engage.

3. System displays the results of the engagement in a message window.

4. Player dismisses window.

4. If either the player's character or the foreign character has no points, the game terminates; or

5. System moves the player's character to a random area different from that in which the encounter took place, and displays it there.


A use case expressed in text - and refined

2.2.3 "Encounter Foreign character" use case

Actor: player of Encounter

1. System moves a foreign character into the area occupied by the playeror Player moves into the area containing a foreign character.

2. System causes the two characters to engage.

3. System displays the results of the engagement

4. If either the player's character or the foreign character has no points, the game terminates; or

5. System moves the player's character to a random area different from that in which the encounter took place, and displays it there.


1.1 create; display

Sequence Diagram for Engage Foreign Character Use Case

2.1 execute

3 create and show

:EngagementDisplay

:Engagement

2.2 change quality values

1.2 create

:Player Character

:EncounterGame

freddie: Foreign

Character



From Sequence diagrams to Domain classes (1)

• these sequence diagrams are figures 13.22, 13.23, 13.24 in Braude SD (with some changes)

• use cases are a beginning point for requirements and analysis

• alternatives include scenarios, event-action cases• no prescribed format: but writing the use cases

• drags needs from the client• drives the analysis of the information model

to identify the “ingredients” - domain classesand some of the actions

• drives refinement, organisation, improvement of specification


From Sequence diagrams to Domain classes (2)

Classes in the Encounter gameclass object

• from Initialize sequence diagram:• EncounterGame (a single object)• PlayerCharacter mainPlayerCharacter• Area dressingRoom• PlayerQualityWindow

(a GUI class for the use case only)

• from Encounter foreign character:• ForeignCharacter freddie• Engagement (a single object)

Other domain classes can come frombrainstorming & paring down.


Other sources of Domain classes?

The use cases do not provide all of the useful classes for writing and organising the specifications

• EncounterGame• PlayerCharacter• Area• PlayerQualityWindow• ForeignCharacter• Engagement• EngagementDisplay• GameCharacter• AreaConnection• ConnectionHyperlink

Other domain classes can come frombrainstorming & paring down

• door• exit• combat• passageway• result• score• rule• quality• . . . and more see fig 13.41


Other sources of Domain classes? (2)

... brainstorming & paring down• Game: not a domain class, too general• GameCharacter : too general – replace by

PlayerCharacter • ForeignCharacter : OK to keep, acts a bit

differently from PlayerCharacter – so introduce EncounterCharacter as common parent

• Quality : omit, try to handle as an attribute of EncounterCharacter

• Room : we already have Area which covers this concept, no need to distinguish any difference


Why look for the domain classes?

• the domain classes are the key concepts (nouns) that should appear in most of our functional requirements statements

• we want to easily match requirements with classes in the design: keeping the domain classes (and adding more classes) is a good starting point for design


Information models – finite state model

anu comp2110 software design lecture 5 comp2110 software design in 2003 lecture 5 requirements...

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