System Development Life Cycle (SDLC)

The systems development life cycle (SDLC) is a general term used to describe the method and process of developing a new information system

Without the structure and organization provided by SDLC approach projects are at risk for missed deadline, low quality etc

SDLC provides

• Structure
• Methods
• Controls
• Checklist

Needed for successful development

Sets of related activities are organized into phases:

1. Project planning phase
2. Analysis phase
3. Design phase
4. Implementation phase
5. Support phase
6. In “classical” life cycle these phases are sequential, but there are variations

The Planning Phase

• Primary objectives are to:

1. identify the scope of the new system,
2. ensure that project is feasible,
3. develop a schedule,
4. allocate resources, 
5. and budget for the remainder of the project.

• The project planning phase includes five activities:

1. Define the problem.
2. Confirm project feasibility.
3. Produce the project schedule.
4. Staff the project.
5. Launch the project.

The Analysis Phase

The primary objective is to understand and document the business needs and the processing requirements of the new system

The analysis phase includes six activities:

• Gather information (e.g. interview, read, observe etc.)

• Define system requirements (reports, diagrams etc.)

• Build prototypes for discovery of requirements

• Prioritize requirements

• Generate and evaluate alternative solutions

• Review recommendations with management

The Design Phase

• The primary objective is to convert the description of the recommended alternative solution into system specification 

• High-level (architectural) design consists of developing an architectural structure for software programs, databases, the user interface, and the operating environment 

• Low-level (detailed) design entails developing the detailed algorithms and data structures that are required for program development

The design phase includes seven activities: 

1. Design and integrate the network 
2. Design the application network 
3. Design the user interfaces 
4. Design the system interfaces 
5. Design and integrate the database 
6. Prototype for design details 
7. Design and integrate the system controls 

The Implementation Phase

• Primary objectives are to ensure that:

1. System is built, tested and installed (actual programming of the system)
2. The users are all trained
3. The business is benefiting

• The implementation phase includes six activities:

1. Construct software components
2. Verify and test
3. Develop prototypes for tuning
4. Convert data
5. Train and document
6. Install the system

The Support Phase

Primary objective is to to keep the system running after its installation
The support phase includes two activities:

Provide support to end users

• Help desks
• Training programs

Maintain and enhance the computer system

• Simple program error correction
• Comprehensive enhancements
• Upgrades

Scheduling of Project Phases
Traditional approach ( “Waterfall method”) – only when one phase is finished does the project team drop down (fall) to the next phase

• Fairly rigid approach
• Can’t easily go back to previous phases (each phase would get “signed off”)
• Good for traditional type of projects, e.g. payroll system or system with clearly definable requirements
• Not as good for many of the new types of interactive and highly complex applications

Newer Approaches:

• The waterfall approach is less used now 
• The phases are still planning, analysis, design and implementation 
• However, many activities are done now in an overlapping or concurrent manner 
• Done for efficiency – when activities are not dependent on the outcome of others they can also be carried out (but dependency limits overlap) 
• Iteration: the process of looping through the same development activities multiple times, sometimes at increasing levels of detail or accuracy 
• Example: Iterative design and development of user interfaces – can cycle iteratively through the following 

1. Design interface 
2. Test with users early on (video-based usability testing) 
3. Redesign, based on results of testing with users

The “Classic” Waterfall Life Cycle

Rapid Prototyping

Spiral - Model

V-Model

Scrum Overview Diagram

Friends , I tried my best of my knowledge, will try to gather more information will post soon.....