MIT5312: Professor KirsThe Systems Development Life Cycle Slide 1 The Systems Development Life Cycle (SDLC)

MIT5312: Professor Kirs The Systems Development Life Cycle Slide 1

The Systems Development Life Cycle (SDLC)


Simon’s Model of Decision Making:1. Intelligence • Is there a Problem??

• Should I get dressed today ??

2. Design • What Alternatives Are there ??

• Should I wear Black Socks? Blue Socks? Red Socks? No Socks??3. Choice • OK – The Red Socks!

Extensions4. Implementation • Put on the darn socks already!!

5. Review • How do they Look (Good, I think)? Was it a good choice?

1916 – 2001 Nobel Laureate, 1978

What is Occam’s Razor and how does it apply here ???


Systems ystems Development evelopment Life ife Cycle (ycle (SDLC))

Generic Term Describes a basic series of activities, not necessarily a

set series of tasks Intended as a ‘top-down’ Approach

• First, Understand the ‘forest’ • Next, Understand the relationships

between the ‘trees’

• Finally, examine each tree closely

Developed for large-scale, organization-wide systems Emphasis on long-term lasting systems

Why do you suppose you can get a better paid job than a Computer Science Major (HINT: it’s notnot because you can program better) ???


But what steps do actually we take when developing an Information System?

Simon’s Model corresponds to the Scientific Approach, which indicates the general tasks needed AND also corresponds to the Systems Development Life Cyle (SDLC):

Simon

Intelligence

System’s Approach

Define Problem

SDLCSystem

InvestigationDesign Develop

Alternatives System Analysis

Choice Select Solution System DesignDesign Solution

Imple-mentation

Implement Solution

Implementation

Review Maintenance


SDLC Activities/ProductsSDLC Activities/Products

Preliminary Investigation

Initial Investigation Formal Investigation Request Usually Requested by Area Manager

What is a System’s Bottleneck ???




Initial Investigation

Problem

Mandate

Opportunity

Formal Investigation Request

Why??

• No System• Faulty or Inadequate System

• Management Ordered• Legal Requirement

• Opportunity to gain Competitive Advantage

Who is it ??

Opportunity, Ma’am

Open Up!!Open Up!!

Usually Requested by Area Manager




Initial Investigation Formal Investigation Request

Is there an order of Preference??


Preference and Priority are often two different things:

• A MANDATE means it must be dealt with first

• A PROBLEM is usually dealt with next

• An OPPORTUNITY implies that it is the type of system which should be developed first

Why Should they be developed First??




Initial Investigation Formal Investigation Request

Why Should they be developed First??


Consider Sabre Reservations Systems (AMR):

• First (fully) installed in 1964• For the year 2001, revenues

were $2.1 billion

• For the year 2001, AMR suffered a 34% decrease in Stock Prices

(This is a little misleading, since both had a VERY bad year in 2001, but it does give some idea about how Strategic Initiatives can help a

Corporation)




Initial Investigation Further Investigation (For Problems)

PIECES Analysis

• Is the System doing what it should be?? Performance

Information • Are the inputs and outputs appropriate ??

Economy • How much is this costing us??

Control • Do we have appropriate security or control

Efficiency • Is the system operating as well as it should ??

Service • Are our customers and users happy with the system ??





PIECES Analysis

• Throughput:

Performance

• Response Times

• Is the amount of information being processed adequate ??

• Is the time between a transaction the response to that request too long ??





PIECES Analysis Information

• Outputs:• Too little information ??

• Too Much information ??

• Irrelevant information ??

• Inaccurate information ??

• Untimely information ??

• Too difficult to produce ??






• Inputs:

• Data Captured in time??• Accurate Data Captured??• Redundant Data Captured??• Too Much Data Captured??• Illegal Data Captured??

• All Data Captured ??






• Stored Data:

• Inaccurate Storage??• Secure Storage??• Well Organized??• Inflexible Data??• Accessible Data??

• Redundant Storage ??





PIECES Analysis

• Costs: Economy

• Profits:

• Unknown ??

• Untraceable ??

• Too High ??

• Can the Market be expanded ??• Are there new markets ??• Can orders be increased ??





PIECES Analysis

• Too Little: Control

• Too Much:

• Ethics Breaches ??• Processing Errors ??

• Inconvenient to Users/Customers ??• Processing Delays ??

• Security Breaches ??

• Slow due to Bureaucracy ??

How do you deal with Right to Privacy Laws AND Freedom of Information Laws ???





PIECES Analysis Efficiency

• People of machines waste materials and Supplies ??

• Excessive Materials/Supplies Required ??

• Excessive Effort Required ??

• People or machines waste time ??

What’s the difference between Efficiency and Effectiveness ??





PIECES Analysis Service

• System too difficult to learn and use ??

• System Incompatibility ??

• System Inflexible ??

• System Produces acceptable results ??





Preliminary Investigation Outcomes

Problem/Opportunity/Directive List

• Urgency of Need• Visibility to clients,

Mgt. And Users• Benefits• Priority (relative to

other Requests)• Initial Solutions







• What types of Data are necessary ??

• What types of processes (e.g., sales, Production) are necessary ??

• What types of interfaces (with systems, users, etc) will be required ??

Project Scope Negotiation







• Preliminary Master Plan (baseline)

• Detailed Problem Analysis Plan (for the next phase)


Project Scheduling







• Steering Committee Selection• Need for Top Management Support


Project Scheduling

Proposal Presentation

• Need for User Support (Champion)

(This is a political Process)


SDLC Activities/ProductsSDLC Activities/ProductsPreliminary Investigation Preliminary Investigation

Further Investigation (For Problems)

Systems Analysis

Physical Study (Problem Analysis) Project Scope P/O/D List Project Scheduling


How does the system work??

What Equipment is Available??

What operations can not be changed??

How does the system relate to overall Company Operations?

Who are the key personnel??

What other systems are related to the system ??

• Users• Managers

Who is this Man ??

NOTE: System’s Analysts are NOT well liked by users




Systems Analysis



Problem Analysis Outcomes

Problem Domain Analysis

• List all files, databases & forms which the system constantly uses/updates/creates

• Define each Business Event for which a process is applied

(Data Modeling)

(Decomposition Models)

• Define all of the locations that the systems serves and all the users at those sites

(Context Diagrams)




Systems Analysis




Problem Domain Analysis Cause and Effect Analysis

• Define the problem (or Opportunity)• Identify what might cause the problem• Identify what effects the problem has• Establish what the OBJECTIVE of the

system is• List what constraints there are inhibiting

meeting system objectives(NOTE: constraints can NOT

be changed)




Systems Analysis




Problem Domain Analysis Cause and Effect Analysis

• Update the Master Plan

Update the Project Plan

• Create a detailed Requirement’s Analysis Plan (for the next phase)

Present Findings• REMEMBER that this is a political

process• IF there is no Management nor User

support, the system WILL fail




Systems Analysis



What SHOULD the system be doing??

What operations need to change?

What equipment is needed?

NOTE: This is where User Assistance is CRITICALCRITICAL

Logical Study (Requirements Analysis) What is needed?? (Not what do we have)

How do you suppose users respond to questions like “What do you need?” ??

How do you suppose users respond to questions like “What do you want?” ??




Systems Analysis



Logical Study (Requirements Analysis)

Requirements Analysis Outcomes

Requirements Definition • Functional Definition

Necessary Inputs, Outputs, Processes and Stored Data

• Non-functional Definition Includes such items as ease-of-

use, budgeting, training, quality management, security, and auditing needs




Systems Analysis





Requirements Definition Prioritize Requirements

• Requires Analysis of all Requirements(Tools needed To be dealt with later)

• Determine Mandatory (Essential) Requirements

• Determine Desirable Requirements

• Rank-Order all requirements within each category




Systems Analysis





Requirements Definition Prioritize Requirements

• Update the Master Plan

Update the Project Plan

• Create a detailed Decision Analysis Plan (the next phase)

???When Does it all End ???

IT DOESN’T !!!

Present Findings• Politics, Politics, Politics !!!




Systems Analysis



Logical Study (Requirements Analysis) Feasibility Study (Decision Analysis)

Is it worthwhile to go on?

“ … That is the question …”

Who is this Man (really)??




Systems Analysis




Decision Analysis Outcomes

Feasibility Study (Decision Analysis)

List of Candidates • Corresponds to Simon’s

concept of ‘Design’ Enumeration of Alternatives

• There should be pre-determined criteria established

• Each Candidate’s strengths and weaknesses should be listed by criteria category




Systems Analysis






List of Candidates Candidate Evaluations

• Operational Feasibility

Will the Users like and accept it?

Will it fit into operations or will it change the work environment?

Does the system fit in the Organization’s mission and Strategic Goals?




Systems Analysis







• Operational Feasibility

Is it compatible with current operations ??

• Technical Feasibility

Do we have the staff to manage it ??

Will it allow for growth ??

Is the hardware and software available ??




Systems Analysis







• Operational Feasibility• Technical Feasibility• Schedule Feasibility

Can the System be designed and implemented within an acceptable period ??




Systems Analysis







• Operational Feasibility• Technical Feasibility• Schedule Feasibility• Economic Feasibility

Is it worth it?? Will Management go along

with it??

The Bottom Line !!!




Systems Analysis







Cost/Benefit Analysis


• Equipment Costs• Development Costs• Training Costs

Tangible Costs:

• Start-up costs• Other known

costs

Intangible Costs: • User Resistance• Customer Resistance• Unexpected Mistakes• Initial loss of

productivity• Other unanticipated

costs




Systems Analysis









Tangible Benefits: Intangible Benefits: • Increased Sales• Decreased Costs• Faster Processing• Increased Capacity• Projected Profits

• Improved Service• Customer Goodwill• New Information• Improved Decisions• Improved Morale




Systems Analysis









How do we evaluate ?? • Payback Period• Return on Investment• Net Present Value

In the final analysis, Benefits MUST outweigh Costs




Systems Analysis







• Operational Feasibility• Technical Feasibility• Schedule Feasibility• Economic Feasibility• Overall Evaluation

Based on comparisons of all candidates (one is always to do nothing) according to all comparison areas




Systems Analysis






List of Candidates Candidate Evaluations Recommendation

Present Recommen-dations to the Steering Committee




Systems Analysis








Recommendation Preferences

1. Do Nothing: If its not broken, Don’t fix it !!

2. Make non-system changes:Procedural Changes

3. Modify Existing System:Change/Add Code

4. Buy the new system: If Possible5. Outsource: A consideration6. Build the new system: If unavoidable




Systems Analysis








Buy vs. Make Considerations

Buy Advantages: Buy Disadvantages : • Cost• Implementation

Time• Tried-and-true• Available

Documentation• Product Support

• Lack of Customization

• Lack of flexibility for change

• Vendor Reliance• Quality of

Documentation• Security Concerns




Systems Analysis








Buy vs. Make Considerations

Make Advantages: Make Disadvantages : • Effectiveness• Control• Security• Documentation

Quality• Ability to make

future changes

• Cost• Initial Reliability• Maintenance• Updating




Systems Analysis








Buy vs. Make Compromises• Customization by vendor • Hybrid Systems

• Vendor Supplies Basic system• Company Develops User Interfaces




Systems Analysis








Outsourcing Considerations• Cost Concerns• Lagging IT Performance• Focus on area of Prime Expertise• Access to specialized skills and

Expertise• Expensing of costs

You’re crazy, Chump !!! Why would I Give up

my job ????Because if YOU don’t, Someone else will




Systems Analysis








Recommendation Outcomes• Reject – The Project is Dead• Reject – Revise and Resubmit• Approve limited-scope project• Approve full-scale version


Systems Analysis


Further Investigation (For Problems) Project Scope P/O/D List Project Scheduling


Physical Study (Problem Analysis) Logical Study (Requirements Analysis) Feasibility Study (Decision Analysis)

Cause/Effect Prob. Domain Candidate List

Candidate Evals. Require. Def. Require. Prior.

Recommendations. Project Scheduling.

Systems Design

Solicit Quotes/Proposals Request for Quote (RFQ)

• System Specifications are well Defined

• The Primary issues are price and vendor reliability

Request for Proposal (RFP)

• The steering committee is open to suggestions about system hard/software

• Basic Requirements and desires are communicated to the vendor

Request for Proposals (RFP) I. Introduction

A. Background B. Brief summary of needs C. Explanation of RFP document D. Call for action on part of vendor

II. Standards and instructions A. Schedule of events leading to contract B. Ground rules that will govern selection decision

1. Who may talk with whom and when 2. Who pays for what 3. Required format for a proposal 4. Demonstration expectations 5. Contractual expectations 6. References expected 7. Documentation expectations

III. Requirements and features A. Hardware

1. Mandatory requirements, features, and criteria 2. Essential requirements, features, and criteria 3. Desirable requirements, features, and criteria

B. Software 1. Mandatory requirements, features, and criteria 2. Essential requirements, features, and criteria 3. Desirable requirements, features, and criteria

C. Service 1. Mandatory requirements 2. Essential requirements 3. Desirable requirements

IV. Technical questionnaires V. Conclusion


Systems Analysis








Systems Design

Solicit Quotes/Proposals

• Criteria Should be established in advance

Validate Vendor Submissions Hard to imagine, but not

ALL Vendor Claims are Accurate

Evaluate/Rank Proposals

Quote/Proposal Outcome

Award Contract Who are these people ??


Systems Analysis




Project Scheduling

• PERT/CPM





Systems Design Design Plan/Schedule

• Other Project Management Tools

• Gantt Charts

Benchmark Establishment

Establish Training Schedule

Solicit Quotes/Proposals


Systems Analysis








Systems Design

Design Plan/Schedule Outcomes

System Design Schedule

• Measurable Benchmarks• Training Schedule

• Sequence of Activities

Development Budget

• Personnel• Materials/Supplies

• Hardware/Software

Design Plan/Schedule Solicit Quotes/Proposals


Systems Analysis








Systems Design System Design


Output Design• Reports and Screens

• User/Mgr. Input absolutely necessary• Commercial Packages available

• Shows Inputs needed

Input Design• Input Data Defined• Input sources identified• Databases Developed


Systems Analysis





Cause/Effect Contract Candidate List





Throughput Design

• Process flow Diagrams

• Outline of Program Procedures

System/User Interfaces

• Descriptions of tie-ins to legacy/other Organizational Systems

• User preferences incorporated

• (Physical) Data Flow Diagrams


Systems Analysis










System Design Outcomes

System Specifications • Outlines how the system should work• Blueprint for system Construction

• Manual for System Developers

Who drew this ??


Systems Analysis










• Case Tools/ 3GLs/4GLs

System Construction

Build and Test Databases Write New Programs

Write Documentation

• According to benchmarks Get User Feedback

Test System

These Activities MAY take

place indepen-dently of

each other

Build and Test Networks


Systems Analysis










System Construction

System Construction Outcomes

Operational System • Although no matter how well it

was designed and tested, there are bound to be some problems


Systems Analysis








Systems Design System Design Design Plan/Schedule Solicit Quotes/Proposals

System Construction Design Sched. Prob. Domain System Specs.

Operational System Dev. Budget. Others

Implemen-tation

Implementation Schedule

Four Major Approaches: Prepare Conversion Plan

Plunge Phased LocationParallel• On a certain

date and time, the new system replaces the old System

• Risky• Cheapest

• New components are added in phases

• If appears to be working well, next component added

• Both the new and old Systems operate concurrently

• Least Risky• Most expensive

• If multiple locations, new system installed in only site first

• May use any of the other approaches


Systems Analysis











Implemen-tation

Implementation Schedule

Four Major Approaches: Prepare Conversion Plan

Systems Acceptance Test• Extensive testing by Users. Designers

monitor:• Ererrs Earrors Errors• Systems Performance• Periods of peak demand• Ease of Use/Difficulties• Audit testing• Others


Systems Analysis











Implemen-tation

Implementation Schedule Prepare Conversion Plan Train Users

• In-House/Off Site • Professional trainers • Train the Trainer/Lead Users

How ???

Monitor User use of Documentation

NOTE: Even the best system is worthless if no one can use it


Systems Analysis











Implemen-tation

Implementation Schedule Prepare Conversion Plan Train Users Convert to New System

Implementation Outcome

Ownership Assigned

Working System !!!


Systems Analysis











Implementation Implementation Schedule Prepare Conversion Plan Train Users Convert to New System

Conv. Plan Impl. Sched System Ownership.

Working System Train. Man. Others

Maintenance Constant Review Periodic Enhancements

Update Manuals on regular basis Organizational Learning

Modifications as needed

Maintenance Outcomes

Improved System NOTE: The SDLC is intended to reduce maintenance costs; It can’t eliminate them


?????????????Any Questions (Please !!!)

?????????????

They must never suspect that I don’t know everything about everything!!!


MIT5312: Professor KirsThe Systems Development Life Cycle Slide 1 The Systems Development Life Cycle (SDLC)

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