apsi - analisa perancangan sistem informasi

Chapter 1Chapter 1

1

Key IdeasMany failed systems were abandoned

because analysts tried to build wonderful systems without understanding the organization.

The primarily goal is to create value for the organization.

2

Key Ideas

The systems analyst is a key person analyzing the business, identifying opportunities for improvement, and designing information systems to implement these ideas.

It is important to understand and develop through practice the skills needed to successfully design and implement new information systems.

3

4

Project PhasesPlanning (Why build the system? How

should the team go about building it?)Analysis (Who uses system, what will it do,

where and when will the system be used?)Design (How will the system work?)Implementation (System delivery)

5

PlanningIdentifying business valueAnalyze feasibilityDevelop work planStaff the projectControl and direct project

6

AnalysisAnalysis strategyGathering business requirementsRequirements definition use casesProcess modelingData modeling

7

DesignDesign selectionArchitecture designInterface designData storage designProgram design

8

ImplementationConstruction

Program buildingProgram and system testing

InstallationConversion strategyTraining planSupport plan

9

Processes and Deliverables

10

Process Product

Planning

Analysis

Design

Implementation

System RequestFeasibility Analysis

Workplan

System Proposal

System Specification

New System and Maintenance Plan

11

12

13

Pros Cons

Identifies systems requirements long before programming begins

Minimizes changes to requirements asproject progresses

Design must be specified on paper before programming begins

Long time between system proposal and delivery of new system

14

15

Pros Cons

Reduces Schedule Time

Less Chance ofRework

Still Uses PaperDocuments

Sub-projects May BeDifficult to Integrate

16

Incorporate special techniques and tools:CASE toolsJAD sessionsFourth generation/visualization programming

languagesCode generators

17

Phased developmentA series of versions developed sequentially

PrototypingSystem prototyping

Throw-away prototypingDesign prototyping

18

Insert Figure 1-4 here

19

Pros Cons

Users Get a SystemTo Use Quickly

Users Can IdentifyAdditional NeedsFor Later Versions

Users Work with aSystem that isIntentionally Incomplete

20

21

Pros Cons

Users Interact withPrototype Very Quickly

Users Can IdentifyNeeded ChangesAnd Refine RealRequirements

Tendency to doSuperficial Analysis

Initial Design Decisions May

Be Poor

22

23

Pros Cons

Risks are Minimized

Important Issues areUnderstood Before the

Real System is Built

May Take LongerThan Prototyping

24

25

Pros Cons

Fast Delivery of Results

Works Well in ProjectsWith Undefined or

Changing Requirements

Requires Discipline

Works Best in Small Projects

Requires MuchUser Input

Object-Oriented Approach

26

Criteria for Selecting the Appropriate Methodology

Clear user requirementsFamiliarity with technologyComplexity of systemReliability of systemTime scheduleSchedule visibility

27

Basic Step to develop an Object Oriented Systems

Identifying business valueAnalyze feasibilityDevelop workplanStaff the projectControl and direct projectRequirements determinationFunctional modelingStructural modelingBehavioral modelingMoving on to design

28

Chapter 2

29

Key IdeasAn opportunity to create business value from

using information technology initiates a project.

Feasibility analysis helps determine whether or not to proceed with the IS project.

Projects are selected based on business needs and project risks.

30

Key IdeasThe project sponsor is a key person who

identifies business value to be gained from using information technology.

The approval committee reviews system requests from groups throughout the organization and selects projects for the benefit of the business.

31

32

IDENTIFYING PROJECTS IDENTIFYING PROJECTS WITH BUSINESS VALUEWITH BUSINESS VALUE

How Do Projects Begin?Business needs should drive projects.Project sponsor recognizes business need for

new system and desires to see it implemented.

Business needs determine the system’s functionality (what it will do).

The project’s business value should be clear.

System RequestA document describing business reasons for

project and system’s expected value.Lists project’s key elements

Project sponsorBusiness needBusiness requirementsBusiness valueSpecial issues or constraints

System Request ExamplesProject sponsor – VP of MarketingBusiness need – Reach new customers and

improve service to existing customersBusiness requirements – Provide web-based

shopping capabilityBusiness value - $750,000 in new customer

sales; $1.8M in existing customer salesSpecial issues or constraints – System must

be operational by holiday shopping season

Preliminary Project AcceptanceSystem request is reviewed by approval

committeeBased on information provided, project

merits are assessed.Worthy projects are accepted and undergo

additional investigation – the feasibility analysis.

Feasibility AnalysisDetailed business case for the project

Technical feasibilityEconomic feasibilityOrganizational feasibility

Compiled into a feasibility studyFeasibility is reassessed throughout the project

37

Technical Feasibility: Can We Build It?

Users’ and analysts’ familiarity with the business application area

Familiarity with technologyHave we used it before? How new is it?

Project sizeNumber of people, time, and features

Compatibility with existing systems

Economic Feasibility: Should We Build It?

Identify costs and benefitsAssign values to costs and benefitsDetermine cash flowAssess financial viability

Net present value (NPV)Return on investment (ROI)Break even point(BEP)

40

Costs Benefits

Tangible

Intangible

***

***

***

***

Assign Cost and Benefit ValuesDifficult, but essential to estimateWork with people who are most familiar with

the area to develop estimatesIntangibles should also be quantifiedIf intangibles cannot be quantified, list and

include as part of supporting material

Organizational Feasibility: If we build it, will they come?

Strategic alignmentHow well do the project goals align with

business objectives?Stakeholder analysis

Project champion(s)Organizational managementSystem users

Project SelectionApproval committee works from the system

request and the feasibility studyProject portfolio – how does the project fit

within the entire portfolio of projects?Trade-offs must be made to select projects

that will form a balanced project portfolioViable projects may be rejected or deferred

because of project portfolio issues.

Chapter 3

44

Key DefinitionsProject management is the process of

planning and controlling the development of a system within a specified timeframe at a minimum cost with the right functionality.

A project manager has the primary responsibility for managing the hundreds of tasks and roles that need to be carefully coordinated.

45

Four Key Steps in Managing Projects

Identifying project sizeCreating and managing the workplanStaffing the projectCoordinating and controlling project

activities

46

47

48

Project Management involvesmaking trade-offs…

Project Size

Pro

ject C

ost

Proj

ect Ti

me

Modifying one elementrequires adjusting the others

Project EstimationThe process of assigning projected values for

time and effortSources of estimates

Methodology in useActual previous projectsExperienced developers

Estimates begin as a range and become more specific as the project progresses

49

50

Planning Analysis Design Implementation

IndustryStandardFor Web 15% 20% 35% 30%Applications

TimeRequired 4 5.33 9.33 8in PersonMonths

Converting Function Points to Lines of Code

51

Source: Capers Jones, Software Productivity Research

Language LOC ratio

CCOBOLJAVAC++

Turbo PascalVisual BasicPowerBuilderHTMLPackages (e.g., Access, Excel)

130110 55 50 50 30 15 1510-40

52

53

Work Plan Information Example

Name of task Perform economic feasibilityStart date ` Jan 05, 2003Completion date Jan 19, 2003Person assigned Mary Smith, sponsorDeliverable(s) Cost-benefit analysisCompletion status OpenPriority HighResources needed SpreadsheetEstimated time 16 hoursActual time 14.5 hours

Identifying TasksMethodology

Using standard list of tasksTop-down approach

Identify highest level tasksBreak them into increasingly smaller unitsOrganize into work breakdown structure

54

Project WorkplanList of all tasks in the work breakdown

structure, plusDuration of taskCurrent task statusTask dependenciesKey milestone dates

55

Tracking Project TasksGantt Chart

Bar chart formatUseful to monitor project status at any point in

timePERT Chart

Flowchart formatIllustrate task dependencies and critical path

56

57

Go to Library

Go to Bookstore

Select and Purchase Book

Skim Book

Write Phase One

Read Book Carefully

Write Phase Two

Task Week 2 3 4 5 6 7 8 9 10 11 12 13

58

Go to Library4 weeks

Select and purchase book

1 weekGo to Bookstore4 weeks

Skim book3 weeks

Write Phase One2 weeks

Read book carefully3 weeks

Write Phase Two3 weeks

59

Staffing AttributesStaffing levels will change over a project’s

lifetimeAdding staff may add more overhead than

additional laborUsing teams of 8-10 reporting in a

hierarchical structure can reduce complexity

60

61

62

63

Planning Analysis Design Implementation

Upper CASE Lower CASE

Integrated CASE (I-CASE)

64

Procedural MetadataLogic

Diagrams ScreenDesigns

CASE Repository

StandardsExamples

Formal rules for naming filesForms indicating goals reachedProgramming guidelines

65

DocumentationProject binderTable of contentsContinual updating

66

Managing RiskRisk assessmentActions to reduce riskRevised assessment

67

Classic MistakesOverly optimistic scheduleFailing to monitor scheduleFailing to update scheduleAdding people to a late project

68

Chapter 4

69

Key DefinitionsThe As-Is system is the current system and

may or may not be computerizedThe To-Be system is the new system that is

based on updated requirementsThe System Proposal is the key deliverable

from the Analysis Phase

70

Key IdeasThe goal of the analysis phase is to truly

understand the requirements of the new system and develop a system that addresses them -- or decide a new system isn’t needed.

The System Proposal is presented to the approval committee via a system walk-through.

Systems analysis incorporates initial systems design.

Requirements determination is the single most critical step of the entire SDLC.

71

What is a Requirement?A statement of what the system must do A statement of characteristics the system

must haveFocus is on business user needs during

analysis phaseRequirements will change over time as

project moves from analysis to design to implementation

72

Requirement TypesFunctional Requirements

A process the system hast to performInformation the system must contain

Nonfunctional RequirementsBehavioral properties the system must have

Operational Performance Security Cultural and political

73

Documenting RequirementsRequirements definition report

Text document listing requirements in outline form

Priorities may be includedKey purpose is to define the project scope:

what is and is not to be included.

74

Basic Steps of Determining Requirements

Understand the “As-Is” systemIdentify improvement opportunitiesDevelop the “To-Be” system conceptTechniques vary in amount of change

Business Process Automation (BPA) – small changeBusiness Process Improvement (BPI) - moderate change Business Process Reengineering (BPR) – significant

changeAdditional information gathering techniques are

needed as well

75

Chapter 5

76

Key IdeasFunctional models describe business

processes and the interaction of an information system with its environment.

Two types of models are used to describe functional models: Activity Diagrams and Usecase Diagrams

Activity diagrams support the logical modeling of business processes and workflows.

Usecase Diagrams are used to describe the basic functions of the information system.

77

Elements of an Activity Diagram

Actions/ActivitiesObject NodesObject FlowsControl NodesControl FlowsSwimlanes

78

Activity Diagram

79

What are Use-Case Descriptions?

Describe basic functions of the system

What the user can doHow the system responds

Use cases are building blocks for continued design activities.

80

How Are Use-Cases Created?Two steps:

Write text-based case descriptionsTranslate descriptions into diagrams

Describes one and only one function, but may have multiple paths.

Developed working with users for content.

81

Types of Use-CasesOverview versus detailEssential versus real

82

83

Use Case Name: ID: Importance Level:

Primary Actor: Use Case Type:

Stakeholders and Interests:

Brief Description:

Trigger:

Relationships: (Association, Include, Extend, Generalization)

Normal Flow of Events:

Subflows:

Alternate/Exceptional Flows:

84

85

Chapter 6

86

Key DefinitionsData model

A formal way of representing the data that are used and created by a business system

Shows the people, places and things about which data is captured and the relationships among them.

Logical data model shows the organization of data without

indicating how it is stored, created, or manipulated.

87

Key DefinitionsPhysical data model

shows how the data will actually be stored in databases or files.

Normalization is the process analysts use to validate data models.

Data models should balance with process models

88

89

What Is an ERD?A picture showing the information created,

stored, and used by a business system. Entities generally represent similar kinds of

informationLines drawn between entities show

relationships among the dataHigh level business rules are also shown

90

Using the ERD to Show Business Rules

Business rules are constraints that are followed when the system is in operation.

ERD symbols can show when one instance of an entity must exist for an instance of another to existA doctor must exist before appointments the

doctor can be made

91

ERD symbols can show when one instance of an entity can be related to only one or many instances of another entityOne doctor can have many patients; each

patient may have only one primary doctorERD symbols show when the existence of

an entity instance is optional for a related entity instanceA patient may or may not have insurance

coverage

92

93

EntityA person, place, event, or thing about

which data is collectedMust be multiple occurrences to be an

entityExample: If a firm has only one warehouse, the

warehouse is not an entity. However, if the firm has several warehouses, the warehouse could be an entity if the firm wants to store data about each warehouse instance.

94

95

AttributesInformation captured about an entityOnly those used by the organization should

be included in the modelAttribute names are nounsSometimes entity name is added at the

beginning of the attribute name for clarity

96

IdentifiersOne or more attributes can serve as the

entity identifier, uniquely identifying each entity instance

Concatenated identifier consists of several attributes

An identifier may be ‘artificial,’ such as creating an ID number

Identifiers may not be developed until the Design Phase

97

98

RelationshipsAssociations between entitiesThe first entity in the relationship is the

parent entity; the second entity in the relationship is the child entity

Relationships should have active verb namesRelationships go in both directions

99

100

Cardinality refers to the number of times instances in one

entity can be related to instances in another entity One instance in an entity refers to one and only

one instance in the related entity (1:1) One instance in an entity refers to one or more

instances in the related entity (1:N) One or more instances in an entity refer to one or

more instances in the related entity (M:N)

101

Modality Refers to whether or not an instance of a child

entity can exist without a related instance in the parent entity Not Null means that an instance in the related

entity must exist for an instance in another entity to be valid

Null means that no instance in the related entity is necessary for an instance in another entity to be valid

102

ERD BasicsDrawing the ERD is an iterative process of

trial and revisionERDs can become quite complex

103

Steps in Building ERDsIdentify the entitiesAdd appropriate attributes for each entityDraw the relationships that connect

associated entities

104

Identify the EntitiesIdentify major categories of information

If available, check the process models for data stores, external entities, and data flows

Check the major inputs and outputs from the use cases

Verify that there is more than one instance of the entity that occurs in the system

105

Add Appropriate AttributesIdentify attributes of the entity that are relevant

to the system under developmentCheck the process model repository entries for

details on data flows and data storesCheck the data requirements of the requirements

definitionInterview knowledgeable usersPerform document analysis on existing forms and

reportsSelect the entity’s identifier

106

Draw the RelationshipsStart with an entity and identify all

entities with which it shares relationshipsDescribe the relationship with the

appropriate verb phraseDetermine the cardinality and modality by

discussing the business rules with knowledgeable users

107

ERD Building TipsOnly include entities with more than one

instance of informationDon’t include entities associated with

implementation of the system (they will be added later)

108

109

110

Best practices rather than rulesEntities should have many occurrencesAvoid unnecessary attributesClearly label all components Apply correct cardinality and modalityBreak attributes into lowest level neededLabels should reflect common business

termsAssumptions should be clearly stated

111

Technique used to validate data models

Series of rules applied to logical data model to improve its organization

Three normalization rules are common

112

Chapter 7

113

Key IdeasA structural or conceptual model

describes the structure of the data that supports the business processes in an organization..

The structure of data used in the system is represented through class diagrams, and object diagrams.

114

Purpose of Structural ModelsReduce the “semantic gap” between the

real world and the world of softwareCreate a vocabulary for analysts and

usersRepresent things, ideas, and concepts of

importance in the application domain

115

ClassesTemplates for creating instances or

objectsConcreteAbstract

Typical examples:Application domain, user interface,

data structure, file structure, operating environment, document, and multimedia classes

116

AttributesUnits of information relevant to the

description of the classOnly attributes important to the task should

be included

117

OperationsAction that instances/objects can takeFocus on relevant problem-specific

operations (at this point)

118

RelationshipsGeneralization

Enables inheritance of attributes and operations

AggregationRelates parts to wholes

AssociationMiscellaneous relationships between classes

119

120

121

Class Diagram Syntax

122

A CLASS

AN ATTRIBUTE

AN OPERATION

AN ASSOCIATION

Class 1

-attribute

+operation ()

Attribute name/derived attribute name

operation name ()

1..* 0..1______verb phrase____

More on AttributesDerived attributes

/age, for example can be calculated from birth date and current date

VisibilityPublicProtectedPrivate

123

More on OperationsConstructor

Creates objectQuery

Makes information about state availableUpdate

Changes values of some or all attributes

124

More on RelationshipsClass can be related to itself (role)Multiplicity

Exactly one, zero or more, one or more, zero or one, specified range, multiple disjoint ranges

Association class

125

Simplifying Class DiagramsThe view mechanism shows a subset of

informationPackages show aggregations of classes (or

any elements in UML)

126

127

Object IdentificationTextual analysis of use-case information

Nouns suggest classesVerbs suggest operations

Creates a rough first cutCommon object listIncidentsRoles

128

PatternsUseful groupings of classes that recur in

various situationsTransactions

Transaction classTransaction line item classItem classLocation classParticipant class

129

Chapter 8

130

Key IdeasBehavioral models describe the internal

dynamic aspects of an information system that supports business processes in an organization

Key UML behavioral models are: sequence diagrams, collaboration diagrams, and statechart diagrams

131

Purpose of Behavioral ModelsTo depict the internal view of business

processesTo show the effects of varied processes on

the system

132

Interaction Diagram Components

ObjectsOperationsMessages

133

Sequence DiagramsIllustrate the objects that participate in a use-

caseShow the messages that pass between

objects for a particular use-case

134

135

136

AN ACTOR

AN OBJECT

A LIFELINE

A FOCUS OF CONTROL

A MESSAGE

OBJECT DESTRUCTION

anObject:aClass

aMessage()

x

137

Determine the context of the sequence diagram

Identify the participating objectsSet the lifeline for each objectAdd messagesPlace the focus of control on each object’s

lifelineValidate the sequence diagram

138

Essentially an object diagram that shows message passing relationships instead of aggregation or generalization associations.

Emphasize the flow of messages among objects, rather than timing and ordering of messages

139

Chapter 9

140

Key DefinitionsThe navigation mechanism provides the way for

users to tell the system what to doThe input mechanism defines the way the system

captures informationThe output mechanism defines the way the

system provides information to users or other systems

141

Key Definitions

The graphical user interface (GUI) is the most common type of interfaces most students are likely to use personally and for developing systems.

142

143

Basic PrinciplesAssume users

Have not read the manualHave not attended trainingDo not have external help readily at hand

All controls should be clear and understandable and placed in an intuitive location on the screen.

144

Basic PrinciplesPrevent mistakes

Limit choicesNever display commands that can’t be used (or

“gray them out”)Confirm actions that are difficult or impossible

to undoSimplify recover from mistakesUse consistent grammar order

145

Types of Navigation ControlLanguages

Command languageNatural language

MenusGenerally aim at broad shallow menuConsider using “hot keys”

Direct ManipulationUsed with icons to start programsUsed to shape and size objectsMay not be intuitive for all commands

146

147

148

149

150

Types of Menus

Menu barDrop-down menuPop-up menuTab menuToolbarImage map

WhenWould YouUse Each ofThese MenuTypes?

Message TipsShould be clear, concise, and completeShould be grammatically correct and free of

jargon and abbreviations (unless they are the users)

Avoid negatives and humor

151

152

Types of Messages

Error messageConfirmation messageAcknowledgment messageDelay messageHelp message

WhenWould YouUse Each ofThese MessageTypes?

153

154

Basic PrinciplesThe goal is to simply and easily capture

accurate information for the systemReflect the nature of the inputsFind ways to simplify their collection

155

Online versus Batch ProcessingOnline processing immediately records the

transaction in the appropriate databaseBatch processing collects inputs over time and

enters them into the system at one time in a batch

Batch processing simplifies data communications and other processes, but means that inventory and other reports are not accurate in real time

156

Capture Data at the SourceReduces duplicate workReduces processing timeDecreases costDecreases probability of error

157

Source Data AutomationCan be obtained by using the following

technologies:bar code readersoptical character recognitionmagnetic stripe readerssmart cards

How can internet be used for source data automation?

158

Minimize KeystrokesNever ask for information that can be

obtained in another wayList selection is more efficient than entering

informationUse default values where possible

159

Types of InputsData items linked to fieldsTextNumbersSelection boxes

160

161

162

Types of Boxes

Check boxRadio buttonOn-screen list boxDrop-down list boxCombo boxSlider

WhenWould YouUse Each ofThese BoxTypes?

163

Types of Validation

Completeness checkFormat checkRange checkCheck digit checkConsistency checkDatabase checks

WhenWould YouUse Each ofThese ValidationMethods?

164

Basic PrinciplesUnderstand report usage

Reference or cover-to-cover?Frequency?Real-time or batch reports?

Manage information loadAll needed information, no more

Minimize bias

165

166

Types of Reports

Detail reportsSummary reportTurnaround documentGraphs

WhenWould YouUse Each ofThese ReportTypes?

167

Electronic

Versus Paper