THE SYSTEM DEVELOPMENT LIFE CYCLE (SDLC)

THE SYSTEM DEVELOPMENT LIFE CYCLE (SDLC)

SYSTEMS ANALYSIS - THE SYSTEM DEVELOPMENT LIFE CYCLE (SDLC)

SDLC refers to the six phase problem solving procedure for examining an information system. It’s the step-by-step process that many organisation follow during system analysis and design.

SDLC has six phases

         i.            Preliminary investigation

       ii.            Systems analysis

     iii.            Systems design

     iv.            Systems development

       v.            System implementation

     vi.            Systems maintenance

 

The Preliminary Investigation - Also called fact finding or feasibility study

Objective: to analyse the current or existing system and decide whether it needs improvement or enhancement, or an entire system needs to be developed altogether.

In this phase the analyst determines:

·         The organisational goal and objective,

·         Nature and scope of the problem

·         Identification of needs

·         Prioritisation of needs

·         Propose alternative solutions: outsource, in house development, and off-the shelf purchase

·         Describe costs and benefits of each solution after undertaking a feasibility study

·         Submit a report with recommendations

 

Assessing the feasibility of the project

Six Categories:

·         Economic

·         Technical

·         Operational

·         Schedule

·         Legal and contractual

·         Political

 

Economic feasibility

·         Cost – Benefit Analysis

·         Determine Benefits

o   Tangible Benefits - Can be measured easily. Examples

§  Cost reduction and avoidance
§  Error reduction
§  Increased flexibility
§  Increased speed of activity
§  Improved management planning and control
§  Opening new markets and increasing sales opportunities
o   Intangible Benefits - Cannot be measured easily. Examples
§  Increased employee morale
§  Competitive necessity
§  More timely information
§  Promotion of organizational learning and understanding

·         Determine Costs

o   Tangible Costs - Can easily be measured in dollars. Example: Hardware

o   Intangible Costs - Cannot be easily measured in dollars. Examples:

§  Loss of customer goodwill
§  Loss of employee morale
o   One-Time Costs - Associated with project startup, initiation and development. Includes:
§  System Development
§  New hardware and software purchases
§  User training
§  Site preparation
§  Data or system conversion

o   Recurring Costs - Associated with ongoing use of the system. Includes:

§  Application software maintenance
§  Incremental data storage expense
§  New software and hardware releases
§  Consumable supplies
§  Incremental communications

·         Time value of money (TVM) - The process of comparing present cash outlays to future expected returns

 

Technical Feasibility - Assessment of the development organization’s ability to construct a proposed system. Project risk can be assessed based upon:

·         Project size
·         Project structure
·         Development group’s experience with the application
·         User group’s experience with development projects and the application area

 

Operational Feasibility

Assessment of how a proposed system solves business problems or takes advantage of opportunities 

Schedule Feasibility

Assessment of time frame and project completion dates with respect to organization constraints for affecting change

Legal and Contractual Feasibility

Assessment of legal and contractual ramifications of new system



Systems Analysis (Second Phase) - Also called detailed investigation

Objective: To determine and make a final decision on whether to develop the current system or develop a new one.

To meet this objective a detailed study has to be undertaken in order to determine what it does and how it does it.

In this phase the system analyst:

·         Gathers data (fact finding), using data collection tools, in order to examine in detail the weakness of the current system and how to improve upon it

o   Task duplication

o   Task overlap

o   Unnecessary delays

o   Uneven workload distribution

·         Analyse the gathered information/facts with the aid of system documentation tools/modelling tools or decision tools

·         Cost/benefit analysis based on new information (update)

·         Writes a report with a plan for further development

·         The analysis phase answers the questions of who will use the system, what the system will do, and where and when it will be used.

·         During this phase the project team investigates any current system(s), identifies improvement opportunities, and develops a concept for the new system.

·         This phase has three analysis steps:

o   Analysis strategy: This is developed to guide the projects team’s efforts. This includes an analysis of the current system.

o   Requirements gathering: The analysis of this information leads to the development of a concept for a new system. This concept is used to build a set of analysis models.

o   System proposal: The proposal is presented to the project sponsor and other key individuals who decide whether the project should continue to move forward.

·         The system proposal is the initial deliverable that describes what business requirements the new system should meet.

·         The deliverable from this phase is both an analysis and a high-level initial design for the new system.

 

System Design (third phase)

In this phase it is decided how the system will operate, in terms of the hardware, software, and network infrastructure; the user interface, forms, and reports that will be used; and the specific programs, databases, and files that will be needed.

Designs

·         Logical/Preliminary Design - Concentrates on business aspects of the system

·         Physical Design - Technical specifications; output requirements, input requirements, storage requirements, processing requirements, system controls and backup

Four design steps

         i.            Design Strategy: This clarifies whether the system will be developed by the company or outside the company

       ii.            Architecture Design: This describes the hardware, software, and network infrastructure that will be used.

     iii.            Database and File Specifications: These documents define what and where the data will be stored.

     iv.            Program Design: Defines what programs need to be written and what they will do.

The design phase ends up with a detailed report

 

System Development (fourth phase)

During this phase, the system is either developed or purchased (in the case of packaged software). This phase is usually the longest and most expensive part of the process.

·         System Construction: The system is built and tested to make sure it performs as designed.

·         Acquisition or purchase of the hardware and software

·         Program/software development (if cannot be purchased)

·         System/program testing: unit and system testing

 

System implementation (fifth phase) - Consists of; 

·         Conversion of hardware, software and files or data

·         Training of users

 

Conversion strategies/approaches

·         Direct approaches: users stop using the old system and switch to the new one on spot

·         Parallel approaches: new and old systems operated side by side until the new system proves reliability

·         Phased approaches: parts of the new systems are introduced or implemented either at different times or all at once in groups

·         Pilot approaches: the entire new system is tried out by some users until reliability is proved then


System maintenance (sixth phase)

·         System changed to reflect changing conditions

·         System obsolescence


·         Adjusts and improves the system through audits, user feedback and periodic evaluation

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