Management Information
System
Thursday, October 15,
2015
CONCEPT OF SYSTEM ANALYSIS DESIGN (SAD), NEED FOR SYSTEM ANALYSIS
& DESIGN, THE PROCESS OF SAD, MIS AND SYSTEM ANALYSIS, SDLC
CONCEPT
System is defined as a
set of elements arranged in an orderly manner to accomplish an objective.
System is not a randomly arranged set. It is arranged with some logic governed
by rules, regulations, principles and policies. Such an arrangement is also influenced
by the objective the system desires to achieve. Systems are created to solve
problems. One can think of the systems approach as an organized way of dealing
with a problem. In this dynamic world, the subject system analysis and design
(SAD) mainly deals with the software development activities.
For example, if a
computer system is designed to perform commercial data processing, then the
elements will be data entry devices, a CPU, a disk, a memory, application
programs and a printer. If a computer is designed to achieve the objective of
design, engineering and drawing processing, then the elements will be the
graphic processor, and the languages suitable for engineering and design
applications, and plotters for drawing the output.
However, a clear statement
of objectives brings a precision and an order into the selection of elements
and their arrangements in the system. Any disorder would create a disturbance
in the system, affecting the accomplishment of the objectives.
If a system in any field
is analyzed. It will be observed that it has three basic parts, which are
organized in an orderly manner. These three parts are:
1. Input
2. Process
3. Output
A system may have single
input and multiple outputs or may have several inputs and outputs. All the systems
operate in an environment. The environment may influence the system in its
design and performance. When a system is designed to achieve certain
objectives, it automatically sets the boundaries for itself. The understanding
of boundaries of the system is essential to bring clarity in explaining the
system components and their arrangements.
A collection of
component that work together to realize some objectives forms a system. In a
system the different components are connected with each other and they are
interdependent. For example, human body represents a complete natural system.
We are also bound by many national systems such as political system, economic
system, educational system and so forth. The objective of the system demands
that some output is produced as a result of processing the suitable inputs. A
well designed system also includes an additional element referred to as
‘control’ that provides a feedback to achieve desired objectives of the system.
The system can be
classified in different categories based on the predictability of its output
and the degree of information exchange with the environment. A system is called
deterministic when the inputs, the process and outputs are known with
certainty. In a deterministic system, when the output can only be predicted in
probabilistic terms. The accounting system is a probabilistic one. A
deterministic system operates in a predictable manner while a probabilistic
system behavior is not predictable.
If a system is
functioning is separated from the environment, then the system does not have
any exchange with the environment nor is it influenced by the environmental
changes then it is called an open system. All kinds of accounting systems, for
example, cash, stocks, attendance of employees, are closed systems. Most of the
systems based on rules and principles are closed systems.
The systems which are
required to respond to changes in the environment such as marketing,
communication and forecasting are open systems. All open systems must have a
self-organizing ability and a sensitivity to absorb and adjust to the business
organization systems of manufacturing are closed systems.
The information system is a combination
of a person (the user of information), the hardware –software system is a
closed deterministic system but in combination with the user it is an open and
a probabilistic system.
Generally, the deterministic systems are
closed, and the probabilistic systems are open. The deterministic and the
closed systems are easy to computerize as they are based on facts and their
behavior can be predicted with certainty. A fixed deposit accounting system, an
invoicing system, and share accounting systems are examples of closed and
deterministic system.
The probabilistic system and the open
systems are complex in every aspect. Hence, they call for considerable amount
of checks and controls so that the system behavior on the performance can be
controlled. All such systems must ideally have self organizing corrective
system to keep the system going its desired path.
For example, the pricing
systems are probabilistic and open. They are to be so designed that the changes
in the taxes and duties, the purchase price and the supply positions are taken
care of, in the sales price computation. Since the pricing system operates
under the influence of the environment, it has to be designed with flexible
computing routines to determine the price. The building of self-organizing
processing routines to respond to the environmental influences is a complex
task both in terms of design and operations of the system.
System
analysis
System analysis may be
understood as a process of collecting and interpreting facts, identifying
problems and using the information to recommend improvements in the system. In
other words system analysis means identification, understanding and examine the
system for achieving predetermined goals/objectives of the system. System
analysis is carried out with the following two objectives:-
1. To know how a system currently operates and
2. To identify the users requirements in the
proposed system
Basically, system analysis
is a detailed study of all important business aspects under consideration and
the existing system, and thus, the study becomes a basis for the proposed
system (may be a modified or an altogether new system). System analysis is
regarded as a logical process. The emphasis in this phase is an investigation
to know how the system is currently operating and to determine what must be
done to solve the problem.
System analysis is the
survey and planning of the project, the study and analysis of the existing
business and information system and the definition of business requirements.
System analysis involves two phases: study phase and definition phase.
Survey phase The purpose of the survey phase is to determine
the worthiness of the project and to create a plan to complete those projects,
deemed worthy. To accomplish the survey phase objectives, the system analyst
will work with the system owner, system users, IS manager and IS staff to:
o 1. Survey problems, opportunities and solutions
o 2. Negotiate project scope
o 3. Plan the project
o 4. Present the project
The system analysis
phase is very important in the total development efforts of a system. The user
may be aware of the problem but may not know how to solve it. During system
analysis, the developer (system designer) works with the user to develop a
logical model of the system. A system analyst, because of his technical
background, may move too quickly to program design to make the system
prematurely physical, which is not desirable and may affect the ultimate
success of the system. In order to avoid this, the system analyst must involve
the user at this stage to get complex information about the system. This can be
achieved if a logical model of the system is developed on the basis of detailed
study. Such a study (analysis) should be done by using various modern tools and
techniques, such as data flow diagrams, data dictionary, and rough description
of the relevant algorithm the final requirement of proposed information system.
System analysis is a process of collecting factual data,
understanding the process involved, identifying problems and recommending
feasible suggestion for improving the system functioning. This involves
studying the business processes, gathering operational data, understand the
information flow, finding out bottlenecks and evolving solutions for overcoming
the weakness of the system so as to achieve the organizational goals. System
analysis also includes subdividing of complex process involving the entire
system, identification of data store and manual process.
The major objectives of
system analysis are to find answers for each business process: what is being
done how is it being done, who is doing it, when is he doing it, why is it
being done and how can it be improved? It is more of a thinking process and
involves the creative skills of the system analyst. It attempts to give birth
to a new efficient system that satisfies the current needs of the user and has
scope for future growth within the organizational constraints. The result of
this process is a logical system design. System analysis is an interactive
process that continues until a preferred and acceptable solution emerges.
SYSTEM DESIGN
Based on the user
requirements and the detailed analysis of the existing system, the new system
must be designed. This is the phase of system designing. It is the most crucial
phase in the development of a system. The logical system design arrived at as a
result of system analysis is converted into physical system design. Normally,
the design proceeds in two stages:
PRELIMINARY OR GENERAL
DESIGN
In the preliminary or
general design, the features of the new system are specified. The costs of
implementing these features and the benefits to be derived are estimated. If
the project is still considered to be feasible (possible), we move to the
detailed design stage.
STRUCTURED OR DETAILED
DESIGN
In the detailed design
stage, computer oriented work begins in earnest. At this stage the design of
the system becomes more structured. Structure design is a blue print of a
computer system solution to a given problem having the same components and
inter-relationships among the same components as the original problem. Input,
output, databases, forms, codifications schemes and processing specifications
are drawn up in detail. In the design stage, the programming language and the
hardware and software platform in which the new system will run are also
decide.
The system design
involves:-
I. Defining precisely the required system output
II. Determining the data requirement for producing
the output
III. Determining the medium and format of files and
databases
IV. Devising processing methods and use of software
to produce output
V. Determine the methods of data capture data input
VI. Designing input forms
VII. Designing codification schemed
VIII. Detailed manual procedures
IX. Documenting the design
SYSTEM
ANALYSIS AND DESIGN
SAD, as performed by the
system analysts, seeks to understand what human need to analyze data input or
data flow systematically, process information in the context of a particular
business. Furthermore, system analysis and design is used to analyze, design
and implements in the support of users and the functioning of business that can
be accomplished through the use of computerized information system.
Installing a system
without proper planning leads to great user dissatisfaction and frequently
causes the system to fall into disuse. System analysis and design lends
structure to the analysis and design of information systems, a costly endeavor
that might otherwise have been done in a haphazard way. It can be thought of as
a series of processes systematically undertaken to improve a business through
the use of computerized information system. SAD involves working with current
and eventual users of information system to support them in working with
technologies in an organizational setting.
THE
NEED FOR SYSTEM ANALYSIS
When you are asked to
computerized a system, it is necessary to analyze the system from different
angles. The analysis of the system is the basic necessity for an efficient
system design. The need for analysis stems from the following point of view:-
System objective: it is
necessary to define the system objectives. Many a times, it is observed that
the systems are historically in operation and have lost their main purpose of
achievement of the objectives. The users of the system and the personnel
involved are not in a position to define the objectives. Since you are going to
develop a computer based system, it is necessary to redefine or reset the
objectives as a reference point in context of current business requirement.
System boundaries: it is
necessary to establish the system boundaries which would define the scope and
the coverage of the system. This helps to short out and understand the
functional boundaries in the system, and the people involved in the system. It
also helps to identify the inputs and the outputs of the various subsystems,
covering the entire system.
System importance: it is
necessary to understand the importance of the system in the organization. This
would help the designer to decide the design feature of the system. It would be
possible then to position the system in relation to the other systems for
deciding the design, strategy and development.
Nature of the system:
the analysis of the system will help the system designer to conclude whether
the system is closed type or an open, and a deterministic or a probabilistic.
Such an understanding of the system is necessary prior to design the process to
ensure the necessary design architecture.
Role of the system as an
interface: the system, many a times, acts as an interface to the other systems.
It is necessary to understand the existing role of the system, as an interface,
to safeguard the interests of the other systems. Any modification or changes
made should not affect the functioning or the objectives of the other system.
Participation of the
user: the strategic purpose of the analysis of the people to a new development.
System analysis process provides a sense of participation to the people. This
helps in breaking the resistance to the new development and it also then
ensures the commitment to the new development and it also then ensures the
commitment to the new system.
Understanding of
resource needs: the analysis of the system helps in defining the resource
requirement in terms of hardware and software. Hence, if any additional
resources are required, this would mean an investment from the point of view of
return on such investment. If the return on such investment from the point of
view of return on such an investment. If the return on the investment is not
attractive, the management may drop the project.
Assessment of
feasibility (practicability): the analysis of the system helps to
establish the feasibility from different angles. The system should satisfy the
technical economic and operational feasibility. Many a time, the systems are
feasible from the technical and economic point of view, but they may be
infeasible from the operational point of view. The assessment of feasibility
will have the investment and the system designer’s time. It would also save the
embracement to the system designer as he is viewed as the key figure in such
project.
MIS AND SYSTEM ANALYSIS
System analysis plays
central role in the development of the MIS. Since the MIS is a corporation of
the various systems, a systematic approach in its development helps in
achieving the objective of the MIS. Each system within the MIS plays a role
which contributes to the accomplishment of the MIS objective.
The tools of the system
analysis and the method of development enforce a discipline on the designer to
follow the steps strictly as stipulated. The possibility of a mistake or an
inadvertence is almost ruled out. The system analysis with its structural
analysis and design approach ensures an appropriate coverage of the subsystems.
The data entities and attributes are considered completely keeping in view the
needs of the systems in question and their interface with other systems.
The systems analysis
begins with the output design which itself ensures that the information needs
are considered and displayed in the appropriate report or screen format; the
subsequent design steps are taken to fulfill these needs.
The MIS may call for an
open system design. In such a case while making the systems analysis and
design, the aspect of open system design is considered and necessary
modification are introduced in the designed the information system.
The user’s application
in the system development ensures the attention to the smaller details in the
design. The users actively come out with their requirements automatically
ensuring that the users are met more precisely.
The systems analysis and
designs, as a tool of the MIS development, helps in streamlining the procedures
of the company to the current needs of the business and information objectives.
New transactio0ns, new documents, new procedures are brought in to make the
system more efficient before it is designed.
The SAD exercise
considers testing the feasibility of the system as an important step. This
step, many a times, saves the implementation of inefficient systems. Sometimes
it forces the management and analysts to look into the requirement and its
genuineness. The MIS development process largely relies on the systems analysis
and design as a source of the scientific development of the MIS.
The development of the
MIS in today advance information technology and internet, web environment is a
challenge. The nature of the system analysis has undergone a change, while the
core process of the analysis and development has remained the same.
The system analysis is
not restricted to the data-process-output. It also covers the technologies
which enables the process feasible. The subject now covers the analysis of
interfacing and supports the technologies and it’s fitting into a chosen
hardware-software platforms for a core system development. The MIS largely
depends on how these technologies are bladed with the main system. The system
architecture of the MIS is now different due to the high tech involvement of
the data capture, communication, and processing technologies. The trend is
towards more swift data capture and making it available in the fastest possible
time leaving its usage to the user.
The development
methodology may be the predictable design of data, databases and file approach
or object oriented analysis and design approach. The MIS design is same, the
difference is in the development cycle time, quality of information efficiency
of design and the case of maintenance of the system.
REQUIREMENT DETERMINATION
It is also termed as a
part of software requirement specification (SRS); it is the starting point of
the system development activity. This activity is considered as the most difficult
and also the most error prone activity because of the communication gap between
the user and the developer. This may be because the user usually does not
understand the users problem and application area. The requirement
determination is a means of translating the ideas given by the user, into a
formal document, and thus to bridge the communication gap. A good SRS provides
the following benefits:-
·
1. It bridges the communication gap between the user and the
developer by acting as a basis of agreement between the two parties.
·
2. It reduces the development cost by overcoming errors and
misunderstandings early in the development.
·
3. It becomes a basis of reference for validation of the final
product and thus acts as a benchmark.
Requirement
determination consists of three activities namely requirement anticipation,
requirement investigation and requirement specification. A requirement
anticipation activity includes the past experience of the analysis, when
influence the study. They may force the likelihood of certain problems or
features and requirements for a new system. Thus, the background of the
analysts to know what to ask or which aspects to investigate can be useful in
at the system investigation. Requirement investigation is at the centre of
system analysis. In this, the existing system is studied and documented for
further analysis. Various methods like fact-finding techniques are used for the
investigation are analyzed to determine requirement specification, which is the
description of the features for a proposed system.
Requirement
determination, in fact, is to learn and collect the information about:-
1. The basic process
2. The data which is used or produced during the process
3. The various constraints in terms of time and volume of work and
4. The performance controls used in the system.
UNDERSTAND
THE PROCESS
Process understanding
can be acquired, if the information is collected regarding:-
1. The purpose of the business activity
2. The steps which and
where they are performed
3. The persons
performing them, and
4. The frequency, time and user of the resulting information
Identify
data used and information generated
Next to process
understanding, an information analyst should find out what data is used to
perform each activity.
Determine
frequency, timing and volume.
Information should also
be collected to know how often the activity is repeated and volume of items to
be handled. Similarly, timing does affect the way analysts evaluate certain
steps in carrying out an activity, in other words, timing, frequency and volume
of activities are important facts to collect.
Know
the performance controls
System controls enable analysts
to understand how business functions can be maintained in an acceptable manner.
In order to understand
the business operations of the organizations and thus to know the existing
system and information requirement for the new system and information analyst
collects the information and then makes an analysis of the collected
information by using certain analysis tools.
Strategies for requirement determination
In order to collect
information so as to study the existing system and to determine information
requirement, there are different strategies, which could be used for the
purpose. These strategies are discussed below:-
Interview: the interview
is a face-to-face method used for collecting the required data. In this method,
a person (the interviewer) asks question from the other person being
interviewed. The interview may be formal or informal and the question asked may
be structured or unstructured. The interview is the oldest and the most often
used device for gathering information about an existing system.
Because of time required
for interviewing and the inability of the users to explain the system in
detail, other methods are also used to gather information. Interviewing is
regarded as an art and it is important that analysts must be trained in the art
of successful interviewing. This is also important because of the fact that the
success of an interviewer and on his or her preparation for interview.
Questionnaire: a
questionnaire is a term used for almost any tool that has questions to which
individual respond. The use of questionnaires allows analysts to collects
information about various aspects of a system from a large number of persons.
The questionnaire may give more reliable data than other fact-finding
techniques. Also the wide distribution ensures greater uncertainty for
responses. The questionnaire survey also helps in saving time as compared to
interviews. The analysts should know the advantages and disadvantages of
structured as well as unstructured questionnaires must be tested and modified
as per the background and experience of the respondents.
Record review: record
review is also known as review of documentation. Its main purpose is to
establish quantitative information regarding volumes, frequencies, trends,
ratios, etc. in record review; analysts examine information that has been
recorded about the system and its users. Records/documents may include written
policy manuals, regulations and standard operating procedures used by the
organization as a guide for managers and other employees. Procedures, manuals
and forms are useful sources for the analysts to study the existing system.
Observation: another
information gathering tool used in system studies is observation. It is the
process of recognizing and noticing people, objects and occurrences to obtain
information. Observation allows analysis to get information. This is difficult
to obtain by any other fact finding method. This approach is most useful when
analysts need to actually observe the way documents are handled, Processes are
carried out and weather specific steps are actually followed. As an observer,
the analyst follows a set of rules. While making observations, he/she is more
likely to listen than talk.
The analysis usually use
a combination of all these approached to study an existing system as any one
approach may not be sufficient for electing information requirement of the
system.
SUMMARY
System analysis is a
detailed study of all important business aspects of a future system, as well as
existing system. Thus, the study becomes a basis for a proposed system. In this
process of system analysis, emphasis is placed on ‘what must be done to solve
the problem’. The final product of system analysis is a set of system
requirement of a proposed information system. Requirement determination, which
is an important activity of system analysis, is a means of translating the
ideas given by the users into a formal document. System analysis ensures that
the system analyst understands the user’s requirements in a clear way and thus
reduces the communication gap between the user and the developer. It reduces
the development cost by overcoming errors and misunderstandings early in the
development and becomes a basis for reference for validation of the final
product.
In order to study the
existing system and to determine information requirements, there are several
strategies which could be used for the purpose. These strategies may include
interviews, questionnaires, record reviews and observation. As any one may not
be sufficient for electing information requirements of the system, the analysis
usually use a combination of all these strategies.
System analysis is
carried out with the help of certain tools. The main tools, which are used for
analyzing and documenting the system specification, are data flow diagram, data
dictionary, structured English, decision trees and decisions tables.
The main objectives of
the system design are to produce system specifications which can then be
converted into an information system for use in the organization. However, the
system design is a creative activity and is considered to evolve through two
different levels of design, i.e. conceptual and detailed design. The conceptual
design which is also called feasibility design sets the direction for the MIS
project and provides performance requirements. The output of the conceptual
design i.e. performance specifications are taken as an input to the detailed
design to produce system specifications. The system specifications thus
generated are handled over to the computer programmer for translating into a
physical information system.
The system
specifications, called detailed system design or logical system design provide
all details of inputs, outputs, file, database controls and procedures. For
ensuring an effective, efficient and successful MIS, the system analysts must
not rush through this phase, rather each and every step must be undertaken very
carefully to prepare a detailed system design.
SYSTEM DEVELOPMENT LIFE CYCLE
System developement life
cycle is an organizational process of developing and maintaining systems. It
helps in establishing a system project plan, because it gives overall list of
processes and sub-processes required for developing a system. System development
life cycle means combination of various activities. In other words we can say
that various activities put together are referred as system development life
cycle. In the System Analysis and Design terminology, the system development
life cycle also means software development life cycle. Following are the
different phases of system development life cycle:
Preliminary study
1. Feasibility study
2. Detailed system study
3. System analysis
4. System design
5. Coding
6. Testing
7. Implementation
8. Maintenance
PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE
Let us now describe the
different phases and related activities of system development life cycle.
(a) Preliminary System Study
Preliminary system study
is the first stage of system development life cycle. This is a brief
investigation of the system under consideration and gives a clear picture of
what actually the physical system is? In practice, the initial system study
involves the preparation of a ‘System Proposal’ which lists the Problem
Definition, Objectives of the Study, Terms of reference for Study, Constraints,
and Expected benefits of the new system, etc. in the light of the user
requirements. The system proposal is prepared by the System Analyst (who studies
the system) and places it before the user management. The management may accept
the proposal and the cycle proceeds to the next stage. The management may also
reject the proposal or request some modifications in the proposal. In summary,
we would say that system study phase passes through the following steps:
· l problem identification and project
initiation
· l background analysis
· l inference or findings (system proposal)
(b) Feasibility Study
In case the system
proposal is acceptable to the management, the next phase is to examine the
feasibility of the system. The feasibility study is basically the test of the
proposed system in the light of its workability, meeting user’s requirements,
effective use of resources and of course, the cost effectiveness. These are
categorized as technical, operational, economic and schedule feasibility. The
main goal of feasibility study is not to solve the problem but to achieve the
scope. In the process of feasibility study, the cost and benefits are estimated
with greater accuracy to find the Return on Investment (ROI). This also defines
the resources needed to complete the detailed investigation. The result is a
feasibility report submitted to the management. This may be accepted or
accepted with modifications or rejected. The system cycle proceeds only if the
management accepts it.
Feasibility
is a measure of how beneficial the development of an information system would
be to an organization. Feasibility analysis is the activity by which the
feasibility is measured. Feasibility study is a preliminary study which
investigates the information needs of prospective users and determines the
resource requirements, costs, benefits and feasibility of a proposed project.
The data is first collected for the feasibility study. Later on, the findings
of the study are formalized in a written report that includes preliminary
specifications and a development plan for the proposed system. If the
management approves these recommendations of the report the development process
can continue.
Types of feasibility
The goal of feasibility
study is to evaluate alternative systems and to propose the most feasible and
desirable system for development. The feasibility of a proposed system can be
evaluated in four major categories:
a) Technical
feasibility: It is a measure of a
technology’s suitability to the application being designed or the technology’s
ability to work with other technologies. It measures the practicality of a
specified technical solution.
b) Economic feasibility: It is the measure of the cost effectiveness of a
project. It is also known as cost benefit analysis.
c) Operational
feasibility: It is a measure of how
comfortable the management and users are with the technology.
d) Schedule feasibility: It is a measure of how reasonable the project
schedule is.
(c) Detailed System Study
The detailed
investigation of the system is carried out in accordance with the objectives of
the proposed system. This involves detailed study of various operations
performed by a system and their relationships within and outside the system.
During this process, data are collected on the available files, decision points
and transactions handled by the present system. Interviews, on-site observation
and questionnaire are the tools used for detailed system study. Using the
following steps it becomes easy to draw the exact boundary of the new system
under consideration:
· Keeping in view the problems and new
requirements
· Workout the pros and cons including new
areas of the system
All the data and the
findings must be documented in the form of detailed data flow diagrams (DFDs),
data dictionary, logical data structures and miniature specification. The main
points to be discussed in this stage are:
·
1. Specification of what
the new system is to accomplish based on the user requirements.
·
2. Functional hierarchy
showing the functions to be performed by the new system and their relationship
with each other
·
3. Functional network,
which are similar to function hierarchy but they highlight the functions which
are common to more than one procedure.
·
4. List
of attributes of the entities – these are the data items which need to be held
about each entity (record)
(d) System Analysis
Systems analysis is a
process of collecting factual data, understand the processes involved,
identifying problems and recommending feasible suggestions for improving the
system functioning. This involves studying the business processes, gathering
operational data, understand the information flow, finding out bottlenecks and
evolving solutions for overcoming the weaknesses of the system so as to achieve
the organizational goals. System Analysis also includes subdividing of complex process
involving the entire system, identification of data store and manual processes.
The major objectives of systems analysis are to find answers for each business
process: What is being done How is it being done, who is doing it, When is he
doing it, Why is it being done and How can it be improved? It is more of a
thinking process and involves the creative skills of the System Analyst. It
attempts to give birth to a new efficient system that satisfies the current
needs of the user and has scope for future growth within the organizational
constraints. The result of this process is a logical system design. Systems
analysis is an iterative process that continues until a preferred and
acceptable solution emerges.
(e) System Design
Based on the user
requirements and the detailed analysis of the existing system, the new system
must be designed. This is the phase of system designing. It is the most crucial
phase in the developments of a system. The logical system design arrived at as
a result of systems analysis is converted into physical system design.
Normally, the design proceeds in two stages:
·
1. Preliminary
or General Design
·
2. Structured
or Detailed Design
Preliminary or General
Design: In the preliminary
or general design, the features of the new system are specified. The costs of
implementing these features and the benefits to be derived are estimated. If
the project is still considered to be feasible, we move to the detailed design
stage.
Structured or Detailed
Design: In the detailed
design stage, computer oriented work begins in earnest. At this stage, the
design of the system becomes more structured. Structure design is a blue print
of a computer system solution to a given problem having the same components and
inter-relationships among the same components as the original problem. Input,
output, databases, forms, codification schemes and processing specifications
are drawn up in detail. In the design stage, the programming language and the
hardware and software platform in which the new system will run are also
decided. There are several tools and techniques used for describing the system
design of the system. These tools and techniques are:
·
1. Flowchart
·
2. Data
flow diagram (DFD)
·
3. Data
dictionary
·
4. Structured
English
·
5. Decision
table
·
6. Decision
tree
The system design
involves:
1. Defining precisely the required system output
2. Determining the data requirement for producing
the output
3. Determining the medium and format of files and
databases
4. Devising processing methods and use of software
to produce output
5. . Determine the methods of data capture and data
input
6. Designing Input forms
7. Designing Codification Schemes
8. Detailed manual procedures
9. Documenting the Design
The
business application system demands designing of systems suitable to the
application in project. The major steps involved in the design are the
following:
Input Design Input design is defined as the input requirement
specification as per a format required. Input design begins long before the
data arrives at the device. The analyst will have to design source documents,
input screens and methods and procedures for getting the data into the
computer.
Output Design – The design of the output is based on the
requirement of the user –manager, customer etc. The output formats have to very
friendly to the user. Therefore the designer has to ensure the appropriateness
of the output format.
Development – When the design and its methodology are
approved, the system is developed using appropriate business models. The
development has to be in accordance to a given standard. The norms have to be
strictly adhered to.
Testing Exhaustive and thorough testing must be
conducted to ascertain whether the system produces the right results. Testing
is time consuming: Test data must be carefully prepared, results reviewed and
corrections made in the system. In some instances, parts of the system may have
to be redesigned. Testing an information system can be broken down into three
types of activities: unit testing, system testing and acceptance test. Unit
testing or program testing consists of testing each program separately in the
system. The purpose of such testing is to guarantee that programs are error
free, but this goal is realistically impossible. Instead, testing should be
viewed as a means of locating errors in programs, focusing on finding all ways
to make a program fail. Once pinpointed, problems can be corrected. System
testing tests the functioning of the information system as a whole. It tries to
determine if discrete modules will function together as planned and whether
discrepancies exist between the way the system actually works and the way it
was conceived. Among the areas examined are performance time, capacity for file
storage and handling peak loads, recovery and restart capabilities and manual
procedures. Acceptance testing provides the final certification that the system
is ready to be used in a production setting. Systems tests are evaluated by
users and reviewed by management. When all parties are satisfied that the new
system meets their standards, the system is formally accepted for installation.
(f) Coding
The system design needs
to be implemented to make it a workable system. This demands the coding of
design into computer understandable language, i.e., programming language. This
is also called the programming phase in which the programmer converts the program
specifications into computer instructions, which we refer to as programs. It is
an important stage where the defined procedures are transformed into control
specifications by the help of a computer language. The programs coordinate the
data movements and control the entire process in a system. It is generally felt
that the programs must be modular in nature. This helps in fast development,
maintenance and future changes, if required.
(g) Testing
Before actually
implementing the new system into operation, a test run of the system is done
for removing the bugs, if any. It is an important phase of a successful system.
After codifying the whole programs of the system, a test plan should be
developed and run on a given set of test data. The output of the test run
should match the expected results. Sometimes, system testing is considered a
part of implementation process. Using the test data following test run are
carried out:
·
1. Program
test
·
2. System
test
Program test: When the
programs have been coded, compiled and brought to working conditions, they must
be individually tested with the prepared test data. Any undesirable happening
must be noted and debugged (error corrections)
System Test: After
carrying out the program test for each of the programs of the system and errors
removed, then system test is done. At this stage the test is done on actual
data. The complete system is executed on the actual data. At each stage of the
execution, the results or output of the system is analyzed. During the result
analysis, it may be found that the outputs are not matching the expected output
of the system. In such case, the errors in the particular programs are
identified and are fixed and further tested for the expected output.
When it is ensured that
the system is running error-free, the users are called with their own actual
data so that the system could be shown running as per their requirements.
(h) Implementation
After having the user
acceptance of the new system developed, the implementation phase begins.
Implementation is the stage of a project during which theory is turned into
practice. The major steps involved in this phase are:
·
1. Acquisition and Installation of Hardware and Software
·
2. Conversion
·
3. User Training
·
4. Documentation
The hardware and the
relevant software required for running the system must be made fully
operational before implementation. The conversion is also one of the most
critical and expensive activities in the system development life cycle. The
data from the old system needs to be converted to operate in the new format of
the new system. The database needs to be setup with security and recovery
procedures fully defined.
During this phase, all
the programs of the system are loaded onto the user’s computer. After loading
the system, training of the user starts. Main topics of such type of training
are:
· How to execute the package
· How to enter the data
· How to process the data (processing details)
· How to take out the reports
After the users are
trained about the computerized system, working has to shift from manual to
computerized working. The process is called ‘Changeover’. The following strategies
are followed for changeover of the system.
(I) Direct
Changeover: This is the
complete replacement of the old system by the new system. It is a risky
approach and requires comprehensive system testing and training.
(ii) Parallel
run: In parallel run both the systems, i.e., computerized and manual,
are executed simultaneously for certain defined period. The same data is
processed by both the systems. This strategy is less risky but more expensive
because of the following:
ü Manual results can be compared with the results
of the computerized system. The operational work is doubled.
ü Failure of the computerized system at the early
stage does not affect the working of the organization, because the manual
system continues to work, as it used to do.
(iii) Pilot run: In this type of run, the new system is run
with the data from one or more of the previous periods for the whole or part of
the system. The results are compared with the old system results. It is less
expensive and risky than parallel run approach. This strategy builds the
confidence and the errors are traced easily without affecting the operations.
The documentation of the system is also one of the most important activities in
the system development life cycle. This ensures the continuity of the system.
There are generally two types of documentation prepared for any system. These
are:
ü User or Operator Documentation
ü System Documentation
The user documentation
is a complete description of the system from the user’s point of view detailing
how to use or operate the system. It also includes the major error messages
likely to be encountered by the users. The system documentation contains the
details of system design, programs, their coding, system flow, data dictionary,
process description, etc. This helps to understand the system and permit
changes to be made in the existing system to satisfy new user needs.
(I) Maintenance
Maintenance is necessary
to eliminate errors in the system during its working life and to tune the
system to any variations in its working environments. It has been seen that
there are always some errors found in the systems that must be noted and corrected.
It also means the review of the system from time to time. The review of the
system is done for:
o knowing the full capabilities of the system
o knowing the required changes or the additional
requirements
o Studying the performance.
After the system has
been fine-tuned, it will need to be maintained while it is in production to
correct errors, meet requirements or improve processing efficiency.
Once a system is fully
implemented and is being used in business operations, the maintenance function
begins. Systems maintenance is the monitoring, or necessary improvements. For
example, the implementation of a new system usually results in the phenomenon
known as the learning curve. Personnel who operate and use the system will make
mistake simply because they are familiar with it. Though such errors usually
diminish as experience is gained with a new system, they do point out areas
where a system may be improved.
Maintenance is also
necessary for other failures and problems that arise during the operation of a
system. End-users and information systems personnel then perform a
troubleshooting function to determine the causes of and solutions to such
problems.
Maintenance also
includes making modifications to an established system due to changes in the business
organizations, and new e-business and e-commerce initiatives may require major
changes to current business systems.
If a major change to a
system is needed, a new project may have to be set up to carry out the change.
The new project will then proceed through all the above life cycle phases.
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