Software Development Skills and SDLC

SOFTWARE DEVELOPMENT SKILLS
Dr. Varun Tiwari
(Associate Professor)
BCA Department
Bosco Technical Training Society , Don Bosco Technical
School (Affiliated to GGSIPU)

OBJECTIVES
 What is Software or System ?
 How to develop a good Software or System ?
 What attributes of designing a good Software or System ?
 Which methodology should be to design a good Software or
System ?
 What is SDLC ?
 How many phases available in SDLC ?

Software: Software is the program & data that make the
hardware do something useful.
Program: Program is a step by step instruction that tell the
computer what action to perform.
Types of Software:
1. System software
2. Application Software
3. Utility Software

System is a word derived from the Greek word ‘Systema’
which means an organized relationship among module
or components.
A System may be defined as orderly grouping of
interdependent components linked together according to
a plan to achieve a specific goal. Each module or
component is a part of total system and it has to do its
own share of work for the system to achieve the desired
goal.

An Information system is an arrangement of people,
data, processes, information presentation and
information technology that interacts to support and
improve day-to-day operations in a business as well as
support the problem solving and decision making needs
of management and users.

The characteristics of a System are as follows:
• Organization implies structure and order. It is an
arrangement of components that helps to achieve
objectives.
• Interaction refers to the procedure in which each
module or Components functions with other module of
the system.
•Interdependence means that one module or
component of the system depends on another module or
component.

• Integration is concerned with how a system is tied
together. It is more than sharing a physical part. It means
that parts of system work together within the system even
though each part performs a unique function.
• Central Objective is quite common that an organization
may set one objective and operate to achieve another.
The important point is that the users must be aware about
the central objective well in advance.

Important Terms Related to Systems
Purpose, Boundary, Environment, Inputs, and Outputs are
some important terms related to Systems.
• A System’s purpose is the reason for its existence and
the reference point for measuring its success.
• A System’s boundary defines what is inside the system
and what is outside.

• A System Environment is everything related to the
System that is outside of its boundaries.
• A System’s Inputs are the physical objects and
information that cross the boundary to enter it from its
environment.
• A system’s Outputs are the physical objects and
information that go from the system into its environment.

Classification of Systems
a) Formal or Informal
b) Physical or Abstract
c) Open or Closed
d) Manual or Automated.

a) A Formal System is one that is planned in advance and is used
according to schedule. In this system policies and procedures are
documented well in advance. A real life example is to conduct a
scheduled meeting at the end of every month in which agenda of
the meeting has already been defined well in advance.
An Informal System is the system that is not described by
procedures. It is not used. According to a schedule. It works on as
need basis. For example, Sales order processing system through
telephone calls.

b) Physical Systems are tangible entities that may be static or
dynamic. Computer Systems, Vehicles, Buildings etc. are
examples of physical systems.
Abstract systems are conceptual entities.
Example: Company
c) Open System is a system within its environment. It receives
input from environment and provides output to environment.

Example: Any real life system, Information System, Organization etc.
Closed System: It is isolated from environment influences. It operates
on factors within the System itself. It is also defined as a System that
includes a feedback loop, a control element and feedback performance
standard.
A closed loop control system is a set of mechanical or electronic devices
that automatically regulates a process variable to a desired state or set
point without human interaction. Closed loop control systems contrast
with open loop control systems, which require manual input.

d) Manual and Automated systems: The system, which does
not require human intervention is called Automated system. In
this system, the whole process is automatic.
Example: Traffic control system for metropolitan cities. The
system, which requires human intervention, is called a Manual
System.
Example: Face to face information center at places like Railway
stations etc.

A real time system describes an interactive processing system
with severe time limitations. A real time system is used when
there are rigid time requirements on the flow of data. A real
time System is considered to function correctly only if it returns
the correct result within imposed time constraints. There are
two types of Real Time systems. They are :
• Hard Real Time Systems which guarantee that critical tasks
are completed on time.

• Soft Real Time Systems which are less restrictive type of
real time systems
where a critical real time task gets priority over other tasks,
and retains the priority until it completes them. Systems that
control scientific experiments, medical imaging systems,
industrial control systems and some display systems are real
time systems.

For making a successful system, the following principles should
be followed:
(1) Both customers and developers should be involved for
accuracy in the information.
(2) A problem solving approach should be adopted. The classic
problem solving approach is as follows:
a) Study, understand the problem and its context
b) Define the requirements of a solution
c) Identify candidate solutions and select the best solution

d) Design and implement the solution
e) Observe and evaluate the solution’s impact and
refine the solution accordingly.
(3) Phases and activities should be established.
(4) For consistent development of a system, some
standards should be established.
These standards are:
Documentation standards: It should be an ongoing activity
during the system development life cycle.

Quality Standards: Checks should be established at every
phase for ensuring that the output of every phase meets the
business and technology expectations.
Automated Tool standards: Hardware and software platforms
should be finalized for the development of Information system.
Automated tool standards prescribe technology that will be
used to develop and maintain information systems and to
ensure consistency, completeness, and quality.

(5) Development of information system should be considered as
capital investment: The developer of an information system
should think about several solutions of a particular problem and
every solution should be evaluated for cost-effectiveness and
risk management. Cost-effectiveness is defined as the result
obtained by striking a balance between the cost of developing
and operating an information system and the benefits derived
from that system. Risk management is defined as the process of
identifying, evaluating and controlling what might go wrong in a
project before it becomes a threat to the successful completion
of the project or implementation of the information system.

(6) Divide and Conquer approach is the way of making a
complex problem easier. In this approach, the larger problem
(System) is divided into smaller problems (Subsystem).
(7) For development of a successful system, the system should
be designed for growth and change. When the System is
implemented, it enters the operations and support stage of Life
Cycle.

PHASES OF SDLC
SDLC consists of mainly seven steps. These are:
1. Project identification and Selection
2. Project Initiation and Planning
3. System Analysis (Requirement)
4. System Design
5. System Development
6. System Testing
7. System Implement and Evaluation
8. System Maintenance

1. Project Identification and Selection: The first phase in the
SDLC is called project identification and selection. In this phase,
the user identifies the need for a new or improved system. In
large organizations, this identification may be part of a systems
planning process. Information requirements of the organization
as a whole are examined, and projects to meet these
requirements are proactively identified. The organization’s
information system requirements may result from requests to
deal with problem in current system’s procedures, from the
desire to perform additional tasks, or from the realization that
information technology could be used to capitalize on an existing
opportunity.

2. Project Initiation and Planning: The second phase is project
initiation and planning. The problems that are identified should
be investigated and a decision to implement the information
system or not for the organization should be taken. A critical step
at this point is determining the scope of the proposed system.
The project leader and initial team of system analysts also
produce a specific plan for the proposed project, which the team
will follow using the 33 remaining SDLC steps. Now, this
baseline project plan customizes the standardized SDLC and
specifies the time and resources needed for its execution.

3. System Analysis:
Analysis is the next phase. During this phase, the analysis has
several sub-phases. The first is requirements determination. In
this sub-phase, analysts work with users to determine the
expectations of users from the proposed system.

In this phase, feasibility study of the proposed system is also
performed. Various types of feasibilities are:
• Technical feasibility
• Economic feasibility
• Behavioral feasibility
• Operational feasibility
• Legal feasibility
• Time feasibility.

4. System Design: After analysis phase is complete, design of the
system begins. The design consists of logical and physical design of
the system. The fourth and fifth phases are devoted to design of the
new and enhanced system. During design, you and the other analysts
convert the description of the recommended alternative solution into
logical and then physical system specifications.
Logical Design:
Logical design is not tied to any specific hardware and systems
software platform. Theoretically, the system could be implemented on
any hardware and systems software. The idea is to make sure that the
system functions as intended. Logical design concentrates on the
business aspects of the system.

Physical Design
In physical design, the logical design is turned into physical or technical
specifications. For example, you must convert diagrams that map the
origin, flow, and processing of data in a system into a structured systems
design that can then be broken down into smaller and smaller units
known as modules for conversion to instruction written in a programming
language. You design various parts of the system to perform the physical
operations necessary to facilitate data capture, processing, and
information output. During the physical design, the analyst team decides
the programming language in which the computer instructions will be
written in, which database system and file structure will be used for the
data, the platform that will be used and the network environment under
which the system will be run. Example are -: DFD,ER Diagram , Class
Diagram , Module etc.

7. Implementation
During implementation, you turn system specification into working system that is tested
and put into use. Implementation includes coding, testing and installation.
During coding, programmers write programs that make up the system. During testing,
programmers and analysts tests the individual programs and the entire system in order
to find and correct errors. During installation, the new system becomes a part of the
daily activities of the organization. Application is installed or loaded, on existing or
new hardware and users are introduced to new system and trained.
Installation of the system can be done in the following three ways:
• Direct conversion: In this type of conversion, the software is directly installed at user’s
site.
• Parallel conversion: In this type of conversion, both the old and new systems are run
in parallel for some time. After monitoring the new system for a reasonable period of
time and if it is performing well, then, the new system is implemented replacing the old
one.
• Phased conversion: In this type of conversion, the system is installed module by
module.

8. Maintenance
The final phase is maintenance. When a system is operating in an organization,
users sometimes find problems with how it works and often think of better ways
to perform its functions. Also, the organization’s requirements with respect to
the system change with time. During maintenance, programmers make the
changes that users ask for and modify the system to reflect and support
changing business conditions. These changes are necessary to keep the system
running and useful. Maintenance is not separate phase but a repetition of the
other lifecycle phases required to study and implement the needed changes.
Thus, maintenance is an overlay to the life cycle rather than a separate phase.
The amount of time and effort devoted to maintenance depends a great deal
on the performance of the previous phase of life cycle.

Maintenance is of three types:
Corrective maintenance: In this type, the errors that creep into the system are
removed. Hence the name corrective maintenance.
Adaptive maintenance: It is done to adapt with the changing external factors.
For example, if the government rules change regarding the Dearness
Allowance from 52% to 58%, then the changes have to be made in the
Information System to adapt with the changing scenario.
Perfective maintenance: This is done to satisfy the users’ requirements to make
the system more and more perfect. The SDLC is a highly linked set of phases
where output of one phase serves as input to the subsequent phase.
Throughout the systems development life cycle, the systems development
project needs to be carefully planned and managed.

PROJECT REPORT
The following items should be included in the Project Report:

Software Development Skills and SDLC

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