1. Design, Implementation and Maintenance
The “lower end” of the lifecycle focuses on
Detailed logical and technical specification of the system or system changes (Design)
The acquisition of hardware and the creation of software (Construction)
Getting the new system in the hands of its intended users with minimal business disruption (Implementation)
Maintaining the effectiveness of the solution as the business evolves (Maintenance)

2. System Design Usual divided into Logical and Physical Logical Design
A detailed conceptualization of “what” the system must do
These are the functional requirements of the system
Logical design differences from requirements analysis in level of detail and specificity

3. System Design Elements
Output design
Reports
Files, transactions
Input design
Screens
Input transactions or files
Processing design
What are the major processing logic and algorithms to be used?
Database and file design
Create the database schema
Define key non-database files

4. System Design Elements (Con’t)
High level physical design
Telecommunications
What are the detailed network and telecom requirements?
Operations
To run the system, what operational procedures must be put in place?
Control and security
What controls will be required to maintain the security and integrity of the system?
Test Design
A preliminary test plan must be created

5. Physical Design
Specification of the system components necessary to implement the logical design
Elements
Hardware
If new hardware is required, this is the place to specify it
What is the system load going to be and is the existing hardware adequate?
What are the storage requirements?
Will new networking equipment be required?

6. Physical Design Elements (Con’t)
Software Design
Identification of individual programs or program modifications
Design of programs
Specification of inputs and outputs
Specification of critical logical components
Test Design
This is the point where the testing plan must be finalized

7. Physical Design Elements (Con’t)
Database Design
The detailed specification of the database and any files is done here
Telecommunication Design
Detailed specifications done
Sufficient to procure hardware or contract work
Security and control

8. Design Phase Checkpoints
Logical and physical designs should be reviewed carefully by all team members
Walkthroughs and reviews of each subsystem
Important for quality and to ensure design consistency
Management Checkpoint
A management checkpoint is critical
Should review all aspects, including cost, ROI and schedule

9. Construction and Test Software is written or purchased
Hardware is purchased
All individual components of system are tested
Integrated system is tested
Detailed implementation plans are created and tested
Training takes place

10. Software Development Structured Design
A body of learning about what constitutes good programs
Maintainable
Error free
Heuristics
Modular
Clearly defined module inputs and outputs, entry and exit points
The opposite of spaghetti

11. Software Development (Con’t)
Structured programming
Specific techniques regarding naming, use of certain programming constructs
Consistent with structured design
Integrated Development Environments (IDE)
Can significantly improve productivity
Use of program walkthroughs
Peer or senior programmer does detailed examination of code
Less expensive way to find errors than testing

12. Software Development (Con’t)
Chief programmer teams
Teams organized around a senior programmer or architect
Team includes
Junior programmers
Librarian
Testing specialists
Documentation and training specialists

13. Testing Must proceed logically from small units to large units
Individual programs
Subsystems comprised of groups of programs
Complete system
Implementation testing
Stress or load testing

14. Testing (Con’t) Testing must be designed based upon test criteria
Test data
Must be constructed which will produce all possible outcomes
Must ensure that all program paths are exercised
Expected results must be documented
And obviously compared with actual
Testing automation tools exist

15. Implementation How do I get all of this installed and running?
Elements
Training people
Converting data from old system to new
Installing hardware
Installing software
Go/No go implementation test
Where do we hit a point of no return?

16. Implementation Alternatives
If system is an addition to existing environment, implementation should be simple
If system replaces an existing system
Big bang approach
Quick, less expensive, more dangerous
Phase in by module
Phase in by part of business

17. Maintenance Maintenance is the “base of the iceberg”
Often, the cost of maintaining a system is 5 times the cost of original acquisition
Impact of design on maintenance
Well designed and well structured systems are much easier to maintain
This means that additional investments during design and construction will yield big benefits during maintenance
“You can pay me now or you can pay me later”

18. Maintenance (Con’t)
Maintenance processes should be managed much like new development
Maintenance authorization should be management decision
Use of SR/MR process
Categorization of request
Bug fix (level of severity)
Enhancement
Externally required
Estimated effort and cost

19. Maintenance (Con’t)
Maintenance should follow a methodology like new development
Requirements analysis
Design
Code review
Test plan and testing
Implementation plan
This should be scaled to the size of the maintenance
System documentation should be maintained as well