system analysis and development module 4
TRANSCRIPT
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SYSTEM DEVELOPMENT
Introduction;Fulfilling the role of system development, a no. of diff. situations
arise, which must be understood to facilitate decisions on the
approach, strategy, technology & development. The user in the
business org has become more literate in terms of knowledge, use of
IT & its application in the mgt of business.
The problem of meeting the changing information needs is solved bykeeping the DB, & the knowledge base at Back end. There are a variety of
systems where system analysis would be required.
Data processing systems
TPSFunctional systems
Integrated systems enterprise mgt
The role of system analyst is a, business analyst, technology expert
& a consultant, giving a solution to the business needs of theinform. Requirement.
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Need for System Analysis;
System objective
System boundariesSystem importance
Nature of the system
Role of the system as an interface
Participation of user
Understanding of resource needs
Assessment feasibility
System Analysis;
Study of end-user information requirements that is needed beforethe design of a new inform system can be completed.
System Design;SD describe what a system should do to meet the inform needs
of users. The strategy specifies how the system will accomplish
the objectives
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System Analysis of the Existing System;
Understanding the existing systemUnderstanding the objectives achieved by the existing
system
Knowing whether the system is feasible in technically
& operationally
Evaluate the system for computerization & its
placement in the total MIS design
System Analysis of a new requirements;
Definition of the system & its objectives
Development of the system
Installation of the system & testing
Operations of the system
Review & evaluation
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INTRODUCTION
The details of the waterfall model vary but two
things remain constant there are boxes goingfrom left downward to the right and there are
arrow connecting each to its succesor.
Water fall model
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DEFINITION
The water fall model is a popular version of thesystem development lifecycle model for softwareengineering.
It is often considered the classic approach to thesystem development life cycle.
In order to design a good system, traditionally, thedevelopment have used the waterfall model.
This model describes a development method that is
linear and sequential. Waterfall development has distinct goals for each
phase of development.
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System Development Model;
We have 2 models for system development
1. Waterfall model (or) Linear sequential model
2. Spiral model Waterfall Model;
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Information needs
specifications
Analysis
System
design
Mission &
Goal
Process design
Testing
Implementation
Maintenance
WaterWaterfallfall modelmodel
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ADVANTAGES
It allows for departmentalization and managerial
control.
Each phase of department proceeds in strictorder without any overlapping.
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DISADVANTAGES
It doesnt allow for much reflection or
revision.
Once an application is in the testing stage, it isvery difficult to go back and change.
Something that was not well though out in the
concept stage.
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The RAD Model
Rapid application development is an incremental S/W development process
model that emphasizes an extremely short development cycle. The RAD
model is a high-speed adaptation of the linear sequential model in whichrapid development is achieved by using component-based construction.
If the requirement are well understood & project scope is constrained,
the RAD process enables a development team to create a fully functional system
within very short time period.
The RAD approach encompasses the following phases;
Business modelingThe information flow among businesses function is molded in a way that
answers the following questions:
1. What information drives the business processes/
2. What information is generated?
3. Who generates it?
4. where does the information go?5. Who rocess it
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Data Modeling;The information flow defined as part of the business modeling phase is
refined into a set of data objects that are needed to support the business.
The characterizes (called attributes) of the each object are identified & the
relationships b/w these objects defined
Process modeling;The data objects defined in the data modeling phase are transformed to
achieve the information flow necessary to implement a business function.Processing description are created for adding, modifying, deleting, or
retrieving a data object.
Application Generation;
RAD assumes the use of the 4th
generation techniques. Rather thancreating S/W using conventional 3rd generation programming languages the
RAD process works to reuse existing program components or create reusable
components. In all cases, automated tools are used to facilitate construction
of the S/W.
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Testing & Turnover;
Since the RAD process emphasize reuse, many of the program componenthave been tested. This re3dusede overall testing time. However, new
components must be tested & all interfaces must be fully exercised.
Advantages ofRAD modelTime constraints imposed on a RAD project demand scalable scope
Each major function to be completed in less than 3 months
Each major function can be addressed by a separate RAD team & then
integrated to form a whole
Disadvantages ofRAD model RAD requires sufficient human resources to create a right number
of RAD team
RAD require developers & customers for rapid-fire activates
Not all type of applications are appropriate for RAD
RAD is not appropriate when technical risks are high
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Business modeling
Data modeling
Process modeling
Testing & Turnover
Application generation
60 90 days
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PROTO TYPE
It typically involves user and developer
The developer interviews the user and develops an
initial system using a DBMS
The user works with the proto type and suggest
changes
Process will repeats until the user or developer is
satisfied
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Steps in system development by proto type:
System development initiated
Investigate and analyze problem sufficiently to develop workable solution
Develop prototype
Put proto type into operation
Refine and modify proto type
Complete component of system
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PROCESS OF PROTO TYPE
Initial interview
MIS designer user
Build initial proto type
New version
Use proto type
Modify proto type
Request changes
Eg: Proto type of an auto-mobile-----subsequent developments made
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PROCESS REPEATS UNTILL:
User is satisfied
Formal system is built by proto typeNeed for application is removed
Process never ends
ADVANTAGES:
Accessible than SDLC
Users wills and wishes are satisfied
Designed to be modified from the starting
Using case tools and DBMS error free code can be generated
Helps heavily in user interaction
DIS-ADVANTAGES :Several users involves
When the project will be finished?
Un capability of analyst
No predefined targets
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SPIRAL MODEL
Spiral model proposed by Boehm
1. It is evolutionary S/W process model2. Spiral have couple of iterative in nature of prototyping with the controlled
& systematic aspects of the linear sequential model
3. It provides the potential for rapid development of incremental versions of
the software
4. During early iteration, the incremental release might be paper model orprototype
5. In later iterations increasingly complete versions of the engineered system
are produced
Spiral model dividing into no. of framework activities, also called task
Regions. Spiral model guiding the risk levels in the projects
Spiral model that contains six task regions;1. Customer communication
2. Planning
3. Risk analysis
4. Engineering
5. Construction & release6. Customer evaluation
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Data Flow Diagram
A graphical system model that shows all of
the main requirements for an information
system: inputs, outputs, processes and datastorage
They are primarily used in the systems
development process.
A data flow diagram is often the diagram of
choice for modern entities.
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Context Diagram
A DFD that summarizes all processing activity
within the system in single process symbol.
Describes highest level view of a systemAll external agents and all data flows into and out
of a system are shown in the diagram
The whole system is represented as one process
The data flows that pass between the externalentities and the system.
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Purpose
To identify and examine the interface between the externalentities and the system.
For ExampleA Context Data Flow Diagram for PayrollProcessing
shows a context diagram for a Payroll Processing that
interacts with 5 agents: Employee, Management,Government Agencies, Human Resources, Timekeeping.
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Symbols used in Context
DiagramA square represents an external data
source or data destination.
A Vowel indicates a internal entity or
transformation process.
A line with an arrow indicates the
direction of the flow of data.
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Guidelines for drawing a Context
Diagram
List potential external entities (people,
places). Look for entities that
G
ive data to the system without explainingthe process that creates that data
Take data from the system withoutexplaining what it does with that data
Establish what flows are sent to and from thesystem from the external entities
Draw the context diagram
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Structured systems Analysis & Design [SSAD]
Symbols;
Flow of data process of Storage of Entity
Transforming Data Data
Example;
Customer ProcessCustomer
order
Order acceptance
Product data
Customer data
Customer
order
Order
acceptance
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Computer Systems Design;
Input Design
Output Design
Processing Design Data Specifications
Procedure Design
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MIS & Systems Analysis
Systems analysis plays a central role in the development of the MIS
MIS lies in the information needs of the various personnel in the org
across all levels of the mgt
The MIS development process largely relies on the SAD as a source of
the scientific development
The modern MIS largely depends on how these technologies are
blended with the main systems
The SA begins with the O/P design
The SA with its structural analysis ensures an appropriate coverage of
the sub-systems
MIS methodology may be the conventional design of data, DB & file
approach
MIS may call for an open system design
Systematic approach in development helps in achieving the objectives
of the MIS
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BUSINESS PROCESS REENGINEERING [BPR]
BPR is a methodology for introducing a fundamental change in
specific business process & usually supported by an IS.Business Process;
A business process is a collection of activities that
--- takes one or more kinds of I/P
--- create an O/P of value to the customers
BPR combines a strategy of promoting business innovation with a strategyof making major improvements to business processes, so that a company can
Become a much stronger & more successful competitor in the marketplace.
Restructuring & transforming a business process by a fundamental
rethinking & redesign to achieve dramatic improvements in the cost,
quality, & speed.
Example; Order Mgt
Proposal Commitment ConfigurationCredit
checkingdelivery
BillingCollections
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Duties & Responsibilities of DBA
Design of the conceptual & physical
schemas
Security &A
uthorization Data availability
Recovery the data from failure
Database tuning
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Definition of System Analyst
A system analyst is the person who selects andconfigures computer systems for anorganization or business.
The analyst must understand the generalobjectives of the business, as well as whateach individual user's job requires.
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ROLES OF SYSTEM ANALYST
Change Agent
Investigator and Monitor
Architect
Psychologist
Salesperson
MotivatorPolitician
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Change Agent
The analyst may be viewed as an agent of change.
Investigator and MonitorIn defining a problem a analyst pieces
together the information gathered to determine
why the present system does not work well andwhat changes we correct the problem.
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ArchitectThe architect s primary function as liaison
between the clients abstract design requirements and
contractor detailed building plan may be compare to analysts
role as liaison between the users logical design requirements
in details and physical system design.
PsychologistThe analyst plays the role of a psychologist in
the way he/she reaches people, interprets their thoughts,
assesses their behavior and draws conclusions from these
interactions.
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SalespersonThe analyst is also playing a role as a sales
persons.
Motivator
A candidate system must be well designed
and acceptable to the user. The analysts roles as
a motivator becomes obvious during the first few
weeks after implementation.
Politician
Related to the role of motivator is that of
politician.
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RESPONSIBILTIES OF
SYSTEM ANALYST
Assists current or potential application users in identifying and describing
problems or opportunities that might be addressed either:a) by implementing a new (automated or manual) system, or
b) by changing an existing application system.
Investigates such problems and opportunities to determine the feasibility of asystem solution.
Analyzes users business requirements in detail.
Assists and guides prospective users of a proposed new or changed system in:
a) quantifying the benefits of having the system, and
b) assessing the impact of the system on their organization and on theoperation of their business. Obtains rough estimates of the cost of operatingand maintaining a proposed new or changed system.
Assists the project manager in identifying the resources needed to implementa new system:
a) the cost of developing or changing the system,
b) the duration of a project to do so.
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Deciding whether to proceed with the implementation.
Prepares, in consultation with users, implementers and
operations representatives, the acceptance test plan for
any new or changed system.
Assists the users in preparing for the installation and
start-up of any new system being implemented.
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Ditties & Responsibilities of DB Designer
Identifying the data to be stored in the DB &for choosing appropriate structures to represent& store this data
DB designer to comm. With all prospectiveDB users
In many cases, the designers are on the staff
of the DBA
DB designers typically interact with each
potential group of users