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Modern Systems Analysis & Design

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The Systems Development Environment

Complex organisational process in which informationsystems are developed and maintained

Result of systems analysis & design is usually development

of application/systems software

Systems development methodologies - systematic

approach..science

Systems development techniques - art of applying

methodologies

Primary responsibility of systems analyst and related teams

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Systems

Group of related parts that function as a Unit collection of people, machines & methods to accomplish

specific objectives

In Computer parlance..

Collection of hardware, software, data Beginning in 1950s. Emphasis was on..

Processes

Automating single function e.g. purchasing or payroll

Considered more as an art and less as science

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System Software

Performs basic functions toestablish and maintain operatingenvironment (Co-ordinates &controls the running of thecomputer)

Works with the computer and notwith the end-user

Operating systems like DOS,UNIX, OS-400 etc. whichperform functions like memorymanagement, secondarystorage management

Device management driverslike printer drivers, mouse

drivers, modem s/w etc. Utilities and editors like filecompression, defragmentationetc.

Language compilers like BASIC,C, COBOL, FORTRAN

Software packages like xBase,

Business Application Software

Uses the environment provided bySystems Software to perform

functions directly needed by end-

users

Generic programs such as Word

processors, electronic spreadsheets,

e-mail etc. Programs to support specific business

functions like TBA, Financial

Accounting packages etc.

Software Systems

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Hardware

O.S.

Systems S/W

Application S/W

Data.

Hardware

Application S/W

Data.

Structure of systems

How it is How it should be

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Business Application Software Phases in Business Application Software

Systems Development Life Cycle (SDLC) Feasibility Study Systems Requirements Specifications Systems Design Programming / Construction

Testing Implementation / Commissioning

Entering history / master data User Training Implementation / commissioning

Live working Post implementation support / modifications

Towards next maturity level

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Feasibility Study

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To set priority of Areas / departments to computerise vis--

vis business focus..TBA vs. Fixed Assets Accounting To finalise overall direction of the Computerisation..

Centralised vs. decentralised, Web-enabled or non-web-enabled

Make or Buy Decision Make.. In house or Outsourcing

Buy..off the shelf with customisation

To gather information about various aspects of

computerisation e.g. hardware, software, information about

about vendors etc.

To finalise Terms-of-reference / time and cost estimates A Feasibility Study Report is the outcome of this phase

Feasibility Study

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Make or BuyMake..In-House

A team of Project Leader, systems analysts, programmers etc. will berequired (may be difficult)

Resulting software would cover most of the user needs with properintegration within the modules.(Advantage)

Complete control and ownership of the resulting software. (Advantage) Less technically and professionally competent software than developed

by outsourced vendor whose main business is software development.(Disadvantage)

Integration with other bought out systems may be difficult e.g. TBAslinkage with voice-mail recognition s/w

Due to high employee turn over in IT field, difficulty in retaining IT staff.This could pose problems for maintaining software and developing newmodules. (Disadvantage)

The time frame required to form such team and developing software maybe more. (Disadvantage) Due to rapid technological advancement in computer field, the IT staff will

have to undergo continuous training in new areas and technologies.

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Make or Buy

Make..Outsourcing Expert team having state-of-the-art knowledge would be involved

in the development (Advantage)

Deliverables by outsourced vendor must be clearly specified.

Rigorous acceptance testing is necessary.(May be difficult)

If more than one vendor, then integration amongst vendors is akey factor.(May be difficult)

Likelihood of vendor/s misusing the source code elsewhere

(Disadvantage) .. IPR issues are to be looked into and involves

lot of legal documentation.

For replication of the software fresh licensing issues & cost may

not be involved (Advantage)

Senior management involvement will be more

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Make or Buy

Buy.. Off the shelf No plug-and-play.. Customisation is necessary. Some product

deficiencies, if any, will have to be accepted.(Disadvantage)

Market research and comparative analysis of different vendors

and their products will have to carried out. Vendors specifications

need to be brought down to a common scalable platform. (May bedifficult).

Vendors capability of providing continuous support must be

ensured.

Software escrow agreement must be entered into and all the legal

documents need to be reviewed by legal counsel.

Total dependability on the vendor(Disadvantage)

Senior management involvement will be more

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Systems Requirement

Specifications (SRS)

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To set Terms-of-reference (TOR) for Software Development (objective

scope and deliverables)

Existing operations along with users additional requirements with

running description and system flow diagrams Interview / meetings with users at various levels along with / observation of

users at work

Document / register / report forms collection and analysis Existing Work flow analysis

BPR requirements

Volume of data, frequency of transactions, entry points are decided

Analysis of authorities / roles / responsibilities of users at various levels

Analysis of locations of computers

Many-a-times Feasibility is merged into this phase and therefore SRSmust be carried out irrespective of Make or Buy decision.

A Systems Requirements Specifications Report is the outcome of this

phase

Systems Requirement Specifications - SRS

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Systems Design

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Organisation of data (temp files, report files) / programs(Source code,

executables, DLLs) on computer is designed

Business rules / requirements of validation of data are specified and

designed as per the analysis done

Various types of charts are prepared such as Systems Flow Chart

(Function wise), Work flow Charts (Actor wise), Data Flow Diagrams,

Decision tables(Business Rules) etc. Design of Database.. E.g. Single / Multiple database, Tables

(Normalisation), relations between tables, Primary / Foreign keys

User interfaces (Screens / Views) / report formats etc are designed

Controls start getting built-up..Authority / security requirements are

specified / designed Users involvement in this phase is minimal but necessary

Plan to convert legacy system to new system

Systems Design

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Types of Systems Operational Information Systems - OIS

e.g. stand-alone and small systems where individual functions ortheir integration is established

Transactions Processing Systems - TPS High-volume..similar to OIS but focus is on capturing data for

entire transaction

Management Information Systems - MIS Usually built on OIS and/or TPS.. Helps enabling management

reporting / decision taking

Decision Support Systems - DSS involves semi-structured problems, requires iterative development,

may not be well-structured

Expert Systems - ES for providing expert advise based on pre-captured knowledge-

base

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CASE TOOLS Computer Aided Software Engineering tools

Refers to the use of s/w packages to aid in the development of allphases of Information Systems I.e. SDLC

Aids designers / programmers to prepare business models and

various flow diagrams

Aids in designing and providing relationships amongst data entities

Changes introduced in one CASE diagram will automatically updateall relevant diagrams

Helps in documentation

Use of CASE tools by developers shall give primary comfort to IS

auditors in respect of standard and consistent methodology followed

Some of the CASE TOOLs : Rational Rose, Systems Architect, Visual

UML etc.

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Client-Server Computing

All client access points should be identified Application code and data may not be located on a single

machine

Mixed platforms (h/w, s/w, networking) may lead to

compatibility problems and confusion

Security issues need to be considered for multiple process

layers in hardware, operating systems, telecommunication

systems, database systems etc.

Version control and program change control may

become complex Testing of system is a complex process

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Web-enabled Software - Some issues More stringent user identification and authentication is required

Use of fire-walls in case of internet applications

Data encryption needs to be built-in to avoid data exposure to

unauthorized users (hackers)

Telecommunication band-width problems leading to slower system

response

Mixed platforms lead to compatibility problems Due to browser based user interfaces, server side processing is done

for allowing access through any browser

Form Fill - submit methodology needs to be adopted to avoid sluggish

response

Performance profile of site needs to be built-up in respect of following Pages visited most often and average visit length

Most typical traffic pattern with peak traffic occurrence

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Programming / Construction

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The Systems Design is converted into Source Programs (Source

Code - human readable form). Source Code is then compiled into Executable Code (Machine

readable form)

Executable code resides on secondary storage and loaded into

memory when executed

Executable cannot be modified. If source code is unavailable,modification to software is not possible.

Programming documentation needs to be done

Two Methodologies Procedural Programming - past trend e.g. COBOL, BASIC, Foxpro - 3

GL

Object Oriented Programming(OOPs) - current trend Visual versions

of BASIC, Foxpro, SQL, C++, JAVA etc. - 4 GL

Programming / Construction

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Procedural ProgrammingAddition Program

Accept A (variable 1), B

(variable 2) from user

C (variable 3) = A + B

Display C as answerFeatures

Each task needs to be

programmed

Less re-usablility

Usually one executable

Procedural Programming vs. OOPs

OOPsAddition Object

Call Accept object

Call summation object

Call display object

Features

Re-usability of objects

Modular(not procedure wise)

development

Unrestricted data types Inheritance, encapsulation,

polymorphism

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Sequence check

Control number follows sequentially and any out-of-sequence number is eitherrejected or reported as an exception

Limit Check Data should not exceed a pre-determined number or range

Validity check

Checking data validity in accordance with pre-determined criteria..e.g. Male /Female check for Sex code

Logical relationship check Checks logical relationship between two data entities.. E.g. relation between

joining date and retirement date

Table look-ups Input data is checked against master data already stored..e.g. Account number

entered gives details of account holder from master data

Few Validation checks

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Testing

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Unit testing ( testing)

Individual function / object / program is tested Normally carried out by programmers / QC

Integration testing Linkages between all related programs is tested for interfaces and overall

functioning

Normally carried out by senior programmers / QC

System testing ( testing) Completed modules are tested for interfaces and overall functioning

Normally carried out by Project Leaders / QC

Regression testing Any changes in coding needs to be tested again in isolation as well as with all

linkages Acceptance testing

Done by users, QC, IS auditors

Testing

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Black-box testing

Internal logic of programs is not examined.. Product is examined and not theprocess

White-box testing Internal logic of programs is examined.. Process is examined and not the

product

Top-down testing Top-level modules are tested first and then explored further into lower levelmodules / programs

Bottom-up testing Lower level modules / programs are tested first and graduated to higher level

modules / programs

The objective of testing is to make the system fail Debugging .. removing the errors

Bebugging .. planting the errors to gauge system response

Approaches to Testing

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Water-fall model (Linear Sequential Model)

Analysis >> Design >> Coding >> Testing

Spiral Model Analysis >> Design >> Coding >> Testing >> Review >>

Prototyping Model

Uses 4GL programming languages which enable faster development Controlled trial & error method Emphasis is on screens and reports acceptable to users Users are misled into believing that the complete system is ready

(processing, transaction volumes, security & controls, back-up &

recovery etc will have to be built later)

Likelihood of resulting system not having proper controls Seldom documented / approved because of the fast development Significant cost & time saving is possible

SDLC Methodologies

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Rapid Application Development Model (RAD) Strategically important systems are developed faster

Well-defined methodology

Reduction in development cost / time while maintaining

quality

Small well-trained development teams are used

Integrated RAD tools(e.g. VB, Magic) are required

Central repository of objects / functions is developed

Rigid limits on development time frames are set

SDLC Methodologies

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Joint Application Development Model (JAD) Introduced by IBM in late 70s

users , managers and analsysts/programmers, scribe, IS

staff work together

usually requires a sponsor JAD session leader is required

disadvantages similar to those of group meetings

Participatory Development (PD)

alternative approach to SDLC

users involvement is more

SDLC Methodologies

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Improper SDLC - Risks

System may not meet end-users needs May exceed financial budget

May exceed budgeted project time

May result into inefficient product

Promote poor or mismanagement of project

Incompatibility with existing systems

Missed business opportunities

Reduced credibility of IS department

Demotivation of staff

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Modern Systems Analysis & Design

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To set priority of Areas / departments to computerise vis--

vis business focus..TBA vs. Fixed Assets Accounting To finalise overall direction of the Computerisation..

Centralised vs. decentralised, Web-enabled or non-web-enabled

Make or Buy Decision Make.. In house or Outsourcing

Buy..off the shelf with customisation To gather information about various aspects of

computerisation e.g. hardware, software, information about

about vendors etc.

To finalise Terms-of-reference / time and cost estimates

A Feasibility Study Report is the outcome of this phase

Feasibility Study

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To set Terms-of-reference (TOR) for Software Development

Existing operations along with users additional requirements withrunning description and system flow diagrams Interview / meetings with users at various levels along with / observation of

users at work

Document / register / report forms collection and analysis

Existing Work flow analysis

BPR requirements

Volume of data, frequency of transactions, entry points are decided

Analysis of authorities / roles / responsibilities of users at various levels

Analysis of locations of computers

Many-a-times Feasibility is merged into this phase and therefore SRS

must be carried out irrespective of Make or Buy decision. A Systems Requirements Specifications Report is the outcome of this

phase

Systems Requirement Specifications - SRS

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Project Identification and Selection

Project Initiation and Planning

Analysis

Logical Design

Physical Design

Implementation

Maintenance

SDLC

SRS

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Accounting Systems

Creating & processing documents Book keeping / filing / register updating

Posting in subsidiary and general ledger

Reconciliation of ledger with all sub-ledgers

Preparation of trial balance

Preparing financial statements such as P & L account, balance sheet, income

statement, cash-flow statement Analysis of authorities / roles / responsibilities of users at various levels

Analysis of locations of computers

Operational Systems Production / Project planning / Scheduling etc. 3 Ms

Inventory / raw material / WIP / finished goods .. JITs etc. Purchase systems

Commercial Systems

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Human Resource Systems

Personnel Administration Payroll and associated processing

Employee performance tracking

Marketing Systems Customer Billing

Accounts receivables

Supply chain management

Customer service management

Banking Systems

Portfolio management systems / Shares accounting systems

School / College / results processing systems

Many more.

Commercial Systems

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Five generally observed types..these are logical types and not physical

Transaction files Master Files

Master files..can also contain transaction data

Reference or Parameter files

System files

Summary files

Temporary files

Reports Printed Reports.. Can be on plain or pre-printed stationery

Display Reports

Queries processing leading to display or printed reports

Types of Files

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Systems Analysis Systems Analysis involves

Study of existing system Study the product and information(data) flows

Formulate strategic requirements for the new system

Evaluate the present system (mainly reassessment)

---------------------------------------------------------------------------------------------

Business Objectives Find out, decompose and document..obtain from stakeholders

Organisation and Job Design Organisation structure

Bifurcation into roles / responsibilities / authorities

Project Management

Study throughobservation, interviews, meetings, reading, presentation,collecting documents etc.

Making use of computer based tools and techniques

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Systems Analysis Techniques Effective Interviewing

Plan your interview Do your homework .. Clients brochures, web-sites, balance sheet

Observe necessary protocols

Know your subject very well

Unstructured interviews Convey your subject/s that this is an unstructured interview

Be very informal / casual and do not interrogate your subject too much

You may not be specific about a topic

Make notes of discussion points in brief

Structured Interviews should follow unstructured interview Convey your subject/s that this is a structured interview

Ask very specific questions Take detailed notes.. If required take a steno or record interview with permission

After the interview, circulate minutes and take formal / informal approval

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Organisation of data (temp files, report files) / programs(Source code,

executables, DLLs) on computer is designed Business rules / requirements of validation of data are specified and

designed as per the analysis done

Various types of charts are prepared such as Systems Flow Chart

(Function wise), Work flow Charts (Actor wise), Data Flow Diagrams,

Decision tables(Business Rules) etc. Design of Database.. E.g. Single / Multiple database, Tables(Normalisation), relations between tables, Primary / Foreign keys

User interfaces (Screens / Views) / report formats etc are designed

Controls start getting built-up..Authority / security requirements are

specified / designed

Users involvement in this phase is minimal but necessary

Plan to convert legacy system to new system

Systems Design

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Process Modeling

Involves graphical representation of functions / processes Functions or processes .. Capture, manipulate, store and distribute data

within or outside of the systems

DFD is a Structured Analysis Technique Out of Requirements Determination, Requirements

Structuring and Alternative generation and selction.. DFD isfor requirements structuring Context data flow diagram DFDs of current physical system DFDs of current logical system

DFDs of proposed logical system DFDs of proposed physical system

Data Flow Diagrams - DFDs

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Data Flow

Data in motion e.g. customer order form, Invoice, Paycheque

Data store is data at rest e.g. a file folder, computer file

Process is work performed to transform, store or distribute

data

Source / Sink is origin and / or destination of the data We do not consider.. Interactions between source & sinks

What a source or sink does with the data

How to control or redesign source or sink

How to provide direct access to source and sinks

Data Flow Diagrams - DFDs

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Process

Data Store

Source/Sink

Data FlowDeMarco & Yourdon symbols Gane & Sarson symbols

Context Diagram

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0

Customer

Customer Order

Receipt

Food Order

Management

Reports

Kitchen

Context Diagram

Rules of DFD

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A B

C

D

E

Rules of DFD

FSource Sink

Rules of DFD

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G

H

I

J

Rules of DFD

A

B

A

A

A

B

A

A

A

AA

C

B

A

Update

Retrieval

K

L

DFD Improper way

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Customer

Record

Payment

Make

BankDeposit

Bank

CustomerMaster

Accounting

Department

Payment

Payment Data

Receipt

Credit Data

Deposit Data

Payment

Data

1.0

2.0

D1

DFD Improper way

DFD Proper way

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Customer

Record

Payment

Make

BankDeposit

Bank

CustomerMaster

Payment

Payment Data

Receipt

Credit Data

Deposit Data

Payment

Data

1.0

2.0

D1

DFD Proper way

Update

Customer

Master

3.0

Level-0 diagram

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Level 0 diagram

Goods Sold FileD2

Inventory FileD1

1.0Customer

Kitchen

Receive and

Transform

Customer

Food Order

Food Order

Update

Goods SoldFile

Formatted

Goods Sold Data

Inventory

Data

3.0

2.0

RestaurantManager

ProduceManagement

Report

4.0

Management

Reports

Daily Inventory Depletion Quantity

Update

Inventory

File

Customer Order

Receipt