Systems Analysis

Dr. Vicki Sauter and FriendsProfessor, Information Systems

University of Missouri Saint Louis

InfoSys 3810Week Three

2013

Systems Analysis and Design

Five fundamental, separable, yet interrelated elements 

Planning … including requirements elicitationAnalysisDesign (including logical design and physical design

( or preliminary design and detailed design) Implementation … which includes coding, test, and

deploymentAnd Maintenance

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Systems Analysis and Design

The waterfall model … a sequential process where one phase is completed before the next is started …

There is significant formalism to this modelThere is little actual use of this model in

today’s Information Systems world

The Waterfall model is just one systems development methodology

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Systems Analysis … A Definition Systems Analysis is an explicit formal inquiry carried out to help someone identify a better course of action and make a better decision than he might otherwise have made.

identification and re-identification) of objectives, constraints, and alternative courses of action

of the probable consequences of the alternatives in terms of costs, benefits, and risks

presentation of the results in a comparative framework so that the decision maker can make an informed choice from among the alternatives

© Principia Cybernetica Web

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Systems and Systems Analysis

Definition of a System

A system is composed of interacting parts that operate together to achieve some objective or purpose. a system is intended to "absorb" inputs, process them in some way and produce outputs (where outputs are defined by goals, objectives or common purposes)

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Different perspectives

… for different needs

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© R.A. Navarro

Based on work by John A. Zachman

VA Enterprise Architecture

DATAWhat

FUNCTIONHow

NETWORKWhere

PEOPLEWho

TIMEWhen

MOTIVATIONWhy

DATAWhat

FUNCTIONHow

NETWORKWhere

PEOPLEWho

TIMEWhen

MOTIVATIONWhy

SCOPE(CONTEXTUAL)

Planner

ENTERPRISEMODEL(CONCEPTUAL)

Owner

SYSTEM MODEL(LOGICAL)

Designer

TECHNOLOGYMODEL(PHYSICAL)

Builder

DETAILEDREPRESENTATIONS(OUT-OF-CONTEXT)

Sub-Contractor

FUNCTIONINGENTERPRISE

SCOPE(CONTEXTUAL)

Planner

ENTERPRISEMODEL

(CONCEPTUAL)

Owner

SYSTEM MODEL(LOGICAL)

Designer

TECHNOLOGYMODEL

(PHYSICAL)

Builder

DETAILEDREPRESENTATIONS(OUT-OF-CONTEXT)

Sub-Contractor

FUNCTIONINGENTERPRISE

Things Important to the Business

Entity = Class of Business Thing

Processes Performed

Function = Class of Business Process

Semantic Model

Ent = Business Entity Rel = Business Relationship

Business Process Model

Proc = Business Process I/O = Business Resources

Business LogisticsSystem

Node = Business Location Link = Business Linkage

Work Flow Model

People = Organization Unit Work = Work Product

Master Schedule

Time = Business Event Cycle = Business Cycle

Business Plan

End = Business Objectiv e Means = Business Strategy

ImportantOrganizations

People = Major Organizations

Business locations

Node = Major Business Locations

Ev ents Significantto the Business

Time = MajorBusiness Event

Business Goalsand Strategy

Ends/Means =Major Business Goals

Logical DataModel

Ent = Data Entity Rel = Data Relationship

Application Architecture

Proc = Application Function I/O = User Views

Distributed SystemArchitecture

Node = IS Function Link = Line Characteristics

Human InterfaceArchitecture

People = Role Work = Deliv erable

ProcessingStructure

Time = System Event Cycle = Processing Cycle

Business RuleModel

End = Structural Assertion Means = Action Assertion

Physical DataModel

Ent = Segment/Table Rel = Pointer/Key

SystemDesign

Proc = Computer Function I/O = Data Elements/Sets

TechnologyArchitecture

Node = Hardware/Softw are Link = Line Specifications

PresentationArchitecture

People = User Work = Screen Format

ControlStructure

Time = Ex ecute Cycle = Component Cycle

RuleDesign

End = Condition Means = Action

DataDefinition

Ent = Field Rel = Address

Program

Proc = Language Statement I/O = Control Block

Netw orkArchitecture

Node = Addresses Link = Protocols

SecurityArchitecture

People = IdentityWork = Job

Timing Definition

Time = InterruptCycle = Machine Cycle

RuleDesign

End = Sub-Condition Means = Step

Data

Ent = Rel =

Function

Proc =I/O =

Netw ork

Node = Link =

Organization

People = Work =

Schedule

Time = Cycle =

Strategy

End = Means =

Based on work by John A. Zachman

VA Enterprise Architecture

DATAWhat

FUNCTIONHow

NETWORKWhere

PEOPLEWho

TIMEWhen

MOTIVATIONWhy

DATAWhat

FUNCTIONHow

NETWORKWhere

PEOPLEWho

TIMEWhen

MOTIVATIONWhy

SCOPE(CONTEXTUAL)

Planner

ENTERPRISEMODEL(CONCEPTUAL)

Owner

SYSTEM MODEL(LOGICAL)

Designer

TECHNOLOGYMODEL(PHYSICAL)

Builder

DETAILEDREPRESENTATIONS(OUT-OF-CONTEXT)

Sub-Contractor

FUNCTIONINGENTERPRISE

SCOPE(CONTEXTUAL)

Planner

ENTERPRISEMODEL

(CONCEPTUAL)

Owner

SYSTEM MODEL(LOGICAL)

Designer

TECHNOLOGYMODEL

(PHYSICAL)

Builder

DETAILEDREPRESENTATIONS(OUT-OF-CONTEXT)

Sub-Contractor

FUNCTIONINGENTERPRISE

Things Important to the Business

Entity = Class of Business Thing

Processes Performed

Function = Class of Business Process

Semantic Model

Ent = Business Entity Rel = Business Relationship

Business Process Model

Proc = Business Process I/O = Business Resources

Business LogisticsSystem

Node = Business Location Link = Business Linkage

Work Flow Model

People = Organization Unit Work = Work Product

Master Schedule

Time = Business Event Cycle = Business Cycle

Business Plan

End = Business Objectiv e Means = Business Strategy

ImportantOrganizations

People = Major Organizations

Business locations

Node = Major Business Locations

Ev ents Significantto the Business

Time = MajorBusiness Event

Business Goalsand Strategy

Ends/Means =Major Business Goals

Logical DataModel

Ent = Data Entity Rel = Data Relationship

Application Architecture

Proc = Application Function I/O = User Views

Distributed SystemArchitecture

Node = IS Function Link = Line Characteristics

Human InterfaceArchitecture

People = Role Work = Deliv erable

ProcessingStructure

Time = System Event Cycle = Processing Cycle

Business RuleModel

End = Structural Assertion Means = Action Assertion

Physical DataModel

Ent = Segment/Table Rel = Pointer/Key

SystemDesign

Proc = Computer Function I/O = Data Elements/Sets

TechnologyArchitecture

Node = Hardware/Softw are Link = Line Specifications

PresentationArchitecture

People = User Work = Screen Format

ControlStructure

Time = Ex ecute Cycle = Component Cycle

RuleDesign

End = Condition Means = Action

DataDefinition

Ent = Field Rel = Address

Program

Proc = Language Statement I/O = Control Block

Netw orkArchitecture

Node = Addresses Link = Protocols

SecurityArchitecture

People = IdentityWork = Job

Timing Definition

Time = InterruptCycle = Machine Cycle

RuleDesign

End = Sub-Condition Means = Step

Data

Ent = Rel =

Function

Proc =I/O =

Netw ork

Node = Link =

Organization

People = Work =

Schedule

Time = Cycle =

Strategy

End = Means =

Zachman Framework, Cont Last

Week

Business Rules

A business rule is a rule of a business, company, or corporation. It is a rule that defines or constrains some aspect of business and always resolves to either true or false. Business rules are intended to assert business structure or to control or influence the behavior of the business. Business rules describe the operations, definitions and constraints that apply to an organization. Business rules can apply to people, processes, corporate behavior and computing systems in an organization, and are put in place to help the organization achieve its goals.

Wikipedia.net

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The Requirements Phase of Process Development

Definition ( Wikipedia)A requirement is a documented need of what a

particular system should be or do.A requirement can be a description of

what a system must do. This type of requirement specifies something that the delivered system must be able to do.

Other types of requirements specify something about the system itself, and how well it performs its functions.

© R.A. Navarro 11/42

Business Processes Design And Development Must Be Based On Formal Requirements

Functional requirements Non-functional requirements Pseudo requirements

Formal Requirements

© R.A. Navarro 12/42

Methodologies for Requirements ElicitationArchival document analysisDocument review Inspiration / Imagineering InterviewsSurveys or QuestionnairesDelphi MethodDirect ObservationContextual InquiryConcept ElicitationFocus GroupsRAD / JADPrototyping

Formal Requirements

Individual- oriented methods

Group- oriented methods

© R.A. Navarro 13/42

Creativity

The Calf Path

One day thru the primeval wood A calf walked home, as good calves should, But made a trail all bent askew, A crooked trail, as all calves do. Since then three hundred years have fled, And I infer, the calf is dead; But still behind he left his trail, And thereon hangs my mortal tale.The trail was taken up next day By a lone dog that passed that way, And then a wise bell-weather sheep Sliding into a rut now deep, Pursued that trail over hill and glade Thru those old woods a path was made.

The Calf Path

And many men wound in and out, And dodged and turned and bent about, and uttered words of righteous wrath Because “twas such a crooked path” But still they follow-do not laugh- The first migrations of that calf.The forest became a lane That bent and turned and turned again; This crooked lane became a road where many a poor horse with his load Toiled on beneath the burning sun, And traveled some three miles in one.

The Calf Path

The years passed on in swiftness fleet, The village road became a street, And this, before the men were aware, A city’s crowded thoroughfare.And soon a central street was this In a renowned metropolis; And men two centuries and a half Followed the wanderings of this calf.Each day a hundred thousand strong Followed this zigzag calf along; And over his crooked journey went The traffic of a continent.

The Calf Path

A hundred thousand men were led By one poor calf, three centuries dead. For just such reverence is lent To well established precedent.A moral lesson this might teach Were I ordained and called to preach.For men are prone to go it blind Along the calf paths of the mind; And work away from sun to sun To do what other men have done.

Sam Walter Foss

Class Discussion

Class Exercise

Re: The UMSL Library SystemYou have all researched the UMSL Library Business RulesYou all understand the function of a library from a student’s point of viewDevelop an Improved set of business rules

Be Creative

Notes

Networking Expectations are defined on the class website

There is a networking opportunity tomorrow morning … Breakfast and Business7:30 am in the MSCFeaturing Juli Niemann … “What

Recovery”

Systems analysis

There are two fundamentally different ways of approaching systems analysis

Process ViewData View

Systems Analysis … Processes vs Data Points of View

Systems Analysis … The Process View

A Process is defined asA sequence of related tasks which combine to

accomplish a functionA transformation

Systems Analysis … The Process View

A system may be “modeled” using a process documentation formalism

A languageA representation Schema

Typical among such schemaVisio IBM Flow-Charting TemplatesIDEF

Systems Analysis … Data View

Data are values of qualitative or quantitative variables 

Data in are typically represented in a structure, often tabular, a tree, or a graph structure.

Data are typically the results of measurements

Data as an abstract concept can be viewed as the lowest level of abstraction  from which information and then knowledge are derived

Systems Analysis … Data View

Data

Information

Knowledge

Wisdom

Systems Analysis … Data View

Systems Analysis … Data View

DFD’s showInput to and output from the system across

the system boundaryInputs and outputs to and from system

elementsFlow among systems elementsStorages

DFD’s do NOT show timing, control etc.

Class Exercise

Working in groups:

Define the data necessary to support a system developed to meet YOUR new library business rules