Question no 1:-

Discuss the role of system development life cycle in system development? Also discuss & compare difference approaches i.e.

Water fall vs. Incremental

State your own opinion in favor or against the above two.

Ans:-

System development:

System development refers to the structuring of hardware & software to achieve the effective & efficient processing of information. Information system are developed keeping in view the needs to be met.

There can be two reasons for system development.

1. A manual information system to be computerized.

2. An already computerized information system is to be replaced with a system that addressed the growing & changing needs of the organization or the old system has become too slow or there are newer more efficient or user friendly developed tools are available.

In both situations the phase followed for system development would be the same.

To develop system various developed models are deployed. The most famous of these models in the system developed life cycle model (SDLC) or Lifecycle Models.

System Development Life Cycle (SDLC):-

System Development Life Cycle (SDLC) is the over all process of developing information systems through multi step process from investigation of initial requirements through analysis, design, implementation & maintenance. SDLC also known as information systems development or application development. SDLC is a system approach to problem solving & is made up of several phases, each comprised of multiple steps. It describes the stages a system passes through from inception until it is discarded or replaced. SDLC provides structure, methods, controls & checklist.

SDLC is a project management technique that divides complex projects into smaller, more easily managed segments or phases. Although system development can be seen a

project itself, but the attribute that makes system development different from regular project is that a project has a definite end & it is unlikely that ongoing maintenance will be included in the scope of the project but this falls in the definition of SDLC.

SDLC for building system:

There are three steps, including in sourcing, self sourcing & out sourcing.

In sourcing:

We defined in sourcing as having IT specialist within an organization for building organization system by planning, defining the system to be developed, defining the project scope, developing the project plan, managing & monitoring the project plan, analyzing the requirements, designing the technical architecture & system models, development, building the database & programs, testing using test scripts, deployment, providing training to the users of the system & maintenance.

Self sourcing:

Self sourcing means having knowledge about workers within organization build the organizations system Align self sourcing applications to the goals of the organization, establish what external assistance will be necessary, documented & formalize the completed system created for future users, providing ongoing supports, prototyping, gathering requirements, creating prototype of system.

Out sourcing:

It is defined as having a third party that is out side the organization to build the organization’s system so expert minds can create the highest quality system by. Out sourcing for development software, selecting a target system, establishing logical requirements, developing a request for a proposal, testing & accepting a solution, monitoring & Reevaluating.

There are different types of SDLC model.

1. Water fall model / classic lifecycle / linear sequential model

2. Incremental models

3. Iterative models

Difference between water fall model & incremental model:

WATER FALL MODEL:

Water fall model is the earliest of software process models. Cascade of phases, the output of one is input to the next. It is a sequential software development model (a process of creation of the software) in which development is seen as flowing steadily downwards (like a waterfall) through the various phases. Various phases of waterfall model are:

1. Need assessment

2. Entry & feasibility study

3. Analysis of the existing system

4. Information processing system design includes, Formulation of strategic requirements, Organizational & job design.

5. Program development includes Application software acquisition & development, Hardware / system software acquisition.

6. Procedures development

7. Testing

8. Conversion

9. Operation & maintenance

To follow the waterfall model, one proceeds from one phase to the next in a purely in a sequential manner. The waterfall model is widely used by large software development houses & for many large government projects. Those who use such methods do not always formally distinguish between the pure waterfall model & the various modified waterfall models, so it can be difficult to discern exactly which models are being used & to what extent.

INCREMENTAL MODEL:

In incremental model software is built not written. Software is constructed step by step in the same way a building is constructed. The products is designed, implemented, integrated & tested as a series of incremental builds, where a build consists of code pieces from various modules

interacting together to provide a specific functional capability & testable as a whole.

These are characteristics of incremental model.

The system development is broken into many mini development projects.

Partial systems are successively built to produce a final total system.

Highest priority requirements tackled early on.

Once an incremental portion is developed, requirements for that increment are frozen.

OPINION IN THE FAVOR OF WATERFALL MODEL:

An argument for the waterfall model is that it places emphasis on documentation as well as source code. In less designed & documented methodologies, should team member leave, much knowledge is lost & may be difficult for a project to recover from. Should a fully working design document be present new team members or even entirely new teams should be able to familiarize themselves by reading the documents. It is simple & arguably more discipline approach rather than what the waterfall adherent sees as chaos, the waterfall model provides a structured approach. The model itself progresses linearly through discrete easily understandable & explainable phases & thus is easy to understand. It also provides easily mark able milestones in the development process. It is perhaps for this reason that the waterfall model used as a beginning example of a development model in many software engineering courses. The waterfall model also requires that implementers follow the well made, complete design ensuring that the integration of the system proceeds smoothly.

OPINION IN THE FAVOR OF INCREMENTAL MODEL:

An argument for incremental model is that in this model risk management is incremental. It reduces risks of change in user requirements. It provides clients flexibility in decision making. Smaller scope for change in user requirements. Working functionality is produced earlier- computation of value to cost ratio.