Design Completion

• A Major Milestone• System is Presented to Users and

Management for Approval

Data Storage

• First, select the storage format• Then optimize:– data storage efficiency– access speed

A good data model

• Simple, straightforward• Minimize wasted space• Nonredundant (data integrity)• Flexible, adaptable to future needs

Physical ERDs

• Entities become tables• Attributes become fields• Add primary keys• Add foreign keys• Add system related components

Optimizing Access Speed

• Tradeoff between storage efficiency and speed– denormalization– archiving– indexing

Programming and Testing a New System

• The Most Potentially Difficult Phase - ‘Reality Time’– Key Tradeoff: Development versus Maintenance

Effort– Lead Programmer Has to Synthesize Many

Members’ Work– End Users Assume Ownership of the Project

Planning the Programming Effort

• Careful Selection of Milestones and Modularity of Programming Tasks are Important

Planning the Programming Effort

• Programs Evolve in Stages:– program specifications– prototype– functional units– alpha test system– beta test system– production system

System Programming and Testing

• Can You Ever Expect a System to be Error Free?• Objectives at This Phase– Identify Flaws

• Operational• Technical• Economic

‘If we didn’t release the program before it was completely tested, the machines would be obsolete - and so would the program -before they were delivered...’

Herbert Schorr, IBM

System Programming and Testing

– Rigorously Test the System– Prepare the Site for Conversion– Prepare to Release the System to the Users

Implementation Planning

• Testing: Stub Tests

test individual routines with dummy linkages

Unit Tests individual modules

Implementation Planning

Testing:• Program Tests– program tests with test data– loading in real data

Implementation Planning

• Testing: Integration Tests

related modules working together

System Tests interfaces between program modules

and other programs data access and updating

Implementation Planning

• Testing: Acceptance Tests

user’s most critical role system functions as expected documentation sufficient personnel adequately trained operating procedures clear appropriate liaisons with technical support staff

System Testing

• The focus here is on ERROR AVOIDANCE• The testing focus then migrates to ERROR

DETECTION• then to ERROR ELIMINATION

System Tests

• Peak Load Test: extreme conditions

• User - Hardware Interface: common usage

problems

• Recovery Test: simulate emergencies

• Average Turnaround Time: verify processing

levels

System Tests

• Documentation: user’s manuals

• Storage: system’s ability to handle interim

files

• Communications: speed, security, accuracy

• Use: gauge impact of user’s actions

Conversion and Implementation

• Parallel– Evolutionary– ‘Safest’– Not Always Feasible

• Phased by Subsystems– Piecewise implementation of logically divisible

components

• Phased by Location (Single Location)– partial implementation in modules, such as divisions or

outlets

Conversion and Implementation

• Phased by Data Characteristic– Phased in functionality for a select subset of accounts

• Crash (Direct)– worst for systems objectives, but often necessary– requires the most planning

• Day One Changeover– minimal data conversion– restart company data base from ‘day one’

Training

• A Function of theConversion Process– Pilot• cycle users through the new system

– Phased• Implement around training schedule

Training

• Crash– hopefuly, train on a prototype– alternately, train the trainers

(cascading)• Parallel– several options, depends on temporary support• work beside the ne system and switch over• work with trainers running old system

Issues to Consider for Conversion Approach

• Risk• Timing of Benefits• Development Time• Personnel Resource Requirements• Computer Resource Requirements• Current System Maintenance

Issues to Consider for Conversion Approach

• Project Management Complexity• Ease of Verification• Training Impact• Fallback Feasibility