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What is Systems Development Life Cycle?

By Dinesh Thakur

Systems development on a large scale was first attempted by the US military in its Department of Defense (DOD) and by the National Aeronautics and Space Administration (NASA). They were therefore instrumental in developing the framework of a sequence of stages or phases for developing a system.

This sequence of distinct stages that a system goes through in its entire life is called the system development life cycle (Anderson 1991). The idea in such frameworks is to understand the detailed issues pertaining to the system in concept development, requirement definition, design, implementation, test and integration, installation, acceptance and operations.
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What are the different stages of system investigation? Explain

By Dinesh Thakur

Preliminary investigation is the first step in the system development project. It is a way of handling the user’s request to change, improve or enhance an existing system. System investigation includes the following two stages:

 1.      Problem definition:

The first responsibility of a system analyst is to prepare a written statement of the objectives of the problem. Based on interviews with the user, the analyst writes a brief description of his/her understanding of the problem and reviews it with both the groups. People respond to written statements. They ask for clarifications and they correct obvious errors or misunderstandings. That is why a clear statement of objectives is important. In other words, proper understanding of the problem is essential to discover the cause of the problem and to plan a directed investigation by asking questions like what is being done. Why? Is there an underlying reason different from the one the user identifies? Following are some possible definitions of problems:

 

a.      The existing system has a poor response time

b.      It is unable to handle the workload.

c.      The problem of cost, that is the economic system is not feasible.

d.      The problem of accuracy and reliability

e.      The required information is not produced by the existing system

f.        The problem of security.

2.      Feasibility study:

The actual meaning of feasibility is viability. This study is undertaken to know the likelihood of the system being useful to the organization. The aim of feasibility study is to assess alternative systems and to propose the most feasible and desirable system for development.

Thus, feasibility study provides an overview of the problem and acts as an important checkpoint that should be completed before committing more resources. The feasibility of a proposed system can be assessed in terms of four major categories as given below:

 

a)      Organizational feasibility: the extent to which a proposed information system supports the objective of the organization’s strategic plan for information systems determines the organizational feasibility of the system project.

b)      Economic feasibility: In this study, costs and returns are evaluated to know whether returns justify the investment in the system project.

c)      Technical feasibility: whether reliable hardware and software, capable of meeting the needs of the proposed system can be acquired or developed by the organizations in the required time is a major concern of the technical feasibility.

d)      Operational feasibility: the willingness and ability of the management, employees, customers, suppliers, etc to operate, use and support a proposed system come under operational feasibility. In other words, the test of operational feasibility asks if the system will work when it is developed and installed.




What are the Different System Development Stages? Discuss each of Them Briefly

By Dinesh Thakur

In order to develop a system successfully, it is managed by breaking the total development process into smaller basic activities or phases. Any system development process, in general, is understood to have the following phases.

• Investigation,
• Analysis,
• Design,
• Construction and testing,
• Implementation, and
• Maintenance.
A brief description of the above-mentioned stages is discussed as follows.

System Investigation

Some problem may be bothering a business organization. The managers in the organization (user) may not be very clear about the problem. Preliminary investigation is the first step in the system development project. The preliminary investigation is a way of handling the user’s request to change, improve or enhance an existing system. System investigation includes the following two sub-stages.

• Problem definition, and
• Feasibility study.

System Analysis

Analysis is a detailed study of the various operations of a business activity (system), along with its boundaries. The objective of this phase is to determine exactly what must be done to solve the problem. Many system analysts have a technical background. The temptation of many technically trained people is to move too quickly to program design, to become pre-maturely physical. System analysis involves a detailed study of:

• The information needs of the organization and its end users.
• Existing information systems (their activities, resources and products).
• The expected information system (in terms of capabilities of IS required to meet the information needs of users).

System Design

System analysis describes WHAT a system should do to meet the information needs of users. System design specifies HOW the system will accomplish this objective. The designing of the system refers to the technical specification that will be implied in constructing the system. The output of the system analysis phase is the input to the system design phase.

The System design should stress on the following three activities.

• User interface
• Data design, and
• Process design

Construction and Testing

Once the system specifications are understood, the system is physically created. The required programs are coded, debugged, and documented. The system should be tested with some test data to ensure its accuracy and reliability.  In fact, construction of the system takes place on the basis of the system design specifications.

Implementation

The system implementation stage involves hardware and software acquisition, site preparation, user training and installation of the system. Then testing of the system, involving all components and procedures should be done. It must be realized that implementation may be the most crucial phase of system.

Maintenance

System maintenance involves the monitoring, evaluating and modifying of a system to make desirable or necessary improvements. In other words, maintenance includes enhancements, modifications or any change from the original specifications.

Waterfall Model

By Dinesh Thakur

The model states that the phases are organized in a Linear Order.  In other words, the output of one phase becomes the input for the next phase. Various phases have already been explained under a general model of system development. The different phases of the waterfall model are:

    Proposal Definition
    Feasibility Study
    Requirement Analysis
    System Design
    Coding & Testing
    Implementation
    System Maintenance
Limitations of the Waterfall Model.  1. The waterfall model assumes that the requirements of a system can be frozen (i.e. baseline) before the design begins. This is possible for systems designed to automate an existing manual system. But for new systems, determining the requirements is difficult, as the user does not even know the requirements. Hence, having unchanging requirements is unrealistic for such projects.

2. Freezing the requirements usually requires choosing the hardware (because it forms a part of the requirements specification). A large project might take a few years to complete. If the hardware is selected early, it is likely that the final software will use a hardware technology on the verge of becoming obsolete. It is a document driven process that requires formal documents at the end of each phase.

3. This model stresses that the requirements should be completely specified before the beginning of the next phase. But it is not possible in all the systems.




Different Approaches to Development of MIS

By Dinesh Thakur

There are two basic approaches for development of MIS :

a) System development life cycle : The system development life cycle have following steps of development :

i) Systems Planning

ii) Systems Analysis

iii) Systems Design

iv) Systems Implementation

v) Systems Operation and Support (System Maintenance)

b) Prototyping : Prototyping is the process of creating an incomplete model of the future full-featured system, which can be used to let the users have a first idea of the completed program or allow the clients to evaluate the program.

Advantages :

i) The designer and implementer can obtain feedback from the users early in the project development.

ii) The client and the contractor can compare that the developing system matches with the system specification, according to which the system is built.

iii) It also gives the engineer some idea about the accuracy of initial project estimates and whether the deadlines can be successfully met.

The process of prototyping involves the following steps :

i) Identify basic requirements.

ii) Develop initial prototype.

iii) Review : The customers, including end-users, examine the prototype and provide feedback for additions or changes.

iv) Revise and Enhance the Prototype : Using the feedback both the specifications and the prototype can be improved. If changes are introduced then a repetition of steps 3 and 4 may be needed.

Types of prototyping : System prototyping are of various kinds. However, all the methods are in some way based on two major types of prototyping :

Throwaway Prototyping : Throwaway or Rapid Prototyping refers to the creation of a model that will eventually be discarded rather than becoming part of the finally delivered system. After preliminary requirements gathering is accomplished, a simple working model of the system is constructed to visually show the users what their requirements may look like when they are implemented into a finished system. The most obvious reason for using Throwaway Prototyping is that it can be done quickly.

Evolutionary Prototyping : Evolutionary Prototyping (also known as Breadboard Prototyping) is quite different from Throwaway Prototyping. The main goal when using

Evolutionary Prototyping is to build a very good prototype in a structured manner so that we can refine it or make further changes to it. The reason for this is that the Evolutionary prototype, when built, forms the heart of the new system, and the improvements and further requirements will be built on to it. It is not discarded or removed like the Throwaway Prototype. When developing a system using Evolutionary Prototyping, the system is continually refined and rebuilt.

Incremental Prototyping : The final product is built as separate prototypes. At the end the separate prototypes are merged in an overall design.

Advantages of Prototyping :

i) Reduced Time and Costs : Prototyping can improve the quality of requirements and specifications provided to developers. Early determination of what the user really wants can result in faster and less expensive software.

ii) Improved and Increased User Involvement : Prototyping requires user involvement and allows them to see and interact with a prototype; allowing them to provide better and more complete feedback and specifications. Since users know the problem better than anyone, the final product is more likely to satisfy the users desire for look, feel and performance.

Disadvantages of Prototyping :

i) Insufficient Analysis : Since a model has to be created, developers will not properly analyse the complete project. This may lead to a poor prototype and a final project that will not satisfy the users.

ii) User Confusion of Prototype and Finished System : Users can begin to think that a prototype, intended to be thrown away, is actually a final system that merely needs to be finished or polished. Users can also become attached to features that were included in a prototype for consideration and then removed from the specification for a final system.

iii) Excessive Development Time of the Prototype : A key property to prototyping is the fact that it is supposed to be done quickly. If the developers forget about this fact, they will develop a prototype that is too complex.

iv) Expense of Implementing Prototyping : The start up costs for building a development team focused on prototyping may be high. Many companies have to train the team for this purpose which needs extra expenses.

 

Stages of Development of MIS

By Dinesh Thakur

In order to develop a system successfully, it is managed by breaking the total development process into smaller basic activities or phases. Any system development process, in general, is understood to have the following phases 

 i) Systems Planning

ii) Systems Analysis

iii) Systems Design

iv) Systems Implementation

v) Systems Operation and Support