SDLC - Systems Development Life Cycle

The systems development life cycle (SDLC) is a conceptual model used in project management that describes the stages involved in an information system development project, from an initial feasibility study through maintenance of the completed application.

Systems development phases:

The System Development Life Cycle framework provides a sequence of activities for system designers and developers to follow. It consists of a set of steps or phases in which each phase of the SDLC uses the results of the previous one.

A Systems Development Life Cycle (SDLC) adheres to important phases that are essential for developers, such as planning, analysis, design, and implementation, and are explained in the section below. A number of system development life cycle (SDLC) models have been created: waterfall, fountain, spiral, build and fix, rapid prototyping, incremental, and synchronize and stabilize. The oldest of these, and the best known, is the waterfall model: a sequence of stages in which the output of each stage becomes the input for the next. These stages can be characterized and divided up in different ways, including the following:

• Preliminary analysis: The objective of phase1 is to conduct a preliminary analysis, propose alternative solutions, describe costs and benefits and submit a preliminary plan with recommendations.

Conduct the preliminary analysis: in this step, you need to find out the organization's objectives and the nature and scope of the problem under study. Even if a problem refers only to a small segment of the organization itself then you need find out what the objectives of the organization itself are. Then you need to see how the problem being studied fits in with them.

Propose alternative solutions: in digging into the organization's objectives and specific problem, you may have already is covered some solutions, other possible solutions can some form interviewing may have already discovered some solutions, other possible solutions can some from interviewing people inside the organization, clients or customers affected by it, suppliers and consultants. You can also study what competitors is doing. With this data, you can have three choices. You can leave the system as is, improve it, or develop a new system.

Describe the costs and benefits.
The Document Deliverables during this phase is : Business Requirement Specification (BRS) or Customer Required Specification( CRS) Or User Requirement Specification(URS).

• Systems analysis, requirements definition: Defines project goals into defined functions and operation of the intended application. Analyzes end-user information needs.

Document Input : Business Requirement Document
Document Deliverables : SRS (Software Requirement Specification)

• Systems design: Describes desired features and operations in detail, including screen layouts, business rules, process diagrams, pseudocode and other documentation.

Document Input : SRS (Software Requirement Specification)
Document Deliverables : Design Document

• Implementation: The real code is written here (coding-phase)

• Integration and testing: Brings all the pieces together into a special testing environment, then checks for errors, bugs and interoperability.

• Acceptance, installation, deployment: The final stage of initial development, where the software is put into production and runs actual business.

• Maintenance: What happens during the rest of the software's life: changes, correction, additions, moves to a different computing platform and more. This is often the longest of the stages.

In the following example (see picture) these stage of the systems development life cycle are divided in ten steps from definition to creation and modification of IT work products:

Not every project will require that the phases be sequentially executed. However, the phases are interdependent. Depending upon the size and complexity of the project, phases may be combined or may overlap.

Strength and Weaknesses of SDLC

Strengths	Weaknesses
Control.	Increased development time.
Monitor large projects.	Increased development cost.
Detailed steps.	Systems must be defined up front.
Evaluate costs and completion targets.	Rigidity.
Documentation.	Hard to estimate costs, project overruns.
Well defined user input.	User input is sometimes limited.
Ease of maintenance.
Development and design standards.
Tolerates changes in MIS staffing.

It is critical for the project manager to establish and monitor control objectives during each SDLC phase while executing projects. To manage and control any SDLC initiative, each project will be required to establish some degree of a Work Breakdown Structure (WBS) to capture and schedule the work necessary to complete the project. The WBS format is mostly left to the project manager to establish in a way that best describes the project work.

Work breakdown structured organization :
The upper section of the work breakdown structure (WBS) should identify the major phases and milestones of the project in a summary fashion. In addition, the upper section should provide an overview of the full scope and timeline of the project and will be part of the initial project description effort leading to project approval. The middle section of the WBS is based on the seven systems development life cycle (SDLC) phases as a guide for WBS task development. The WBS elements should consist of milestones and “tasks” as opposed to “activities” and have a definitive period (usually two weeks or more). Each task must have a measurable output (e.x. document, decision, or analysis). A WBS task may rely on one or more activities (e.g. software engineering, systems engineering) and may require close coordination with other tasks, either internal or external to the project. Any part of the project needing support from contractors should have a statement of work (SOW) written to include the appropriate tasks from the SDLC phases. The development of a SOW does not occur during a specific phase of SDLC but is developed to include the work from the SDLC process that may be conducted by external resources such as contractors and struct.

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