info1409 2006/7 DMU 1 The story so far… Systems Analysis & Design Academic Year 2008/9 Lecture 10 Lecture 10
Dec 21, 2015
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The story so far…
Systems Analysis & DesignAcademic Year 2008/9
Lecture 10Lecture 10
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Lecture Objectives
This lecture is to review the work we have done so far in Lectures 1 to 9.
We will take a look at a ‘thumbnail sketch’ of the module content in order to
consolidate your learning.
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Lecture 1 – What is a system?
Lecture 1 introduced the idea of the components of a system.
Input/output Process Feedback and feed-forward (controls) System boundary
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Control in systems
Inputs Outputs
Process
Control
SystemBoundary
Environment
Feed-forward
Feed-back
Control flows
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We also considered Info systems
Information systems operate in terms of:
Goals ( the desired long/medium term outcomes)
Elements – (the required hardware & software)
Inputs – (the type and quantity of data)
Outputs – (the result of the processing operations)
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Lecture 2 –How businesses use Info systems
Lecture 2 examines modern information systems and how they provide for new types of business operations.
Information processing, also includes communication systems and the Internet.
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Impact of the Internet
Internet based commerce is called: e-commerce (electronic commerce) or I-
commerce (Internet commerce)
E-commerce includes 2 main sectorsB2C – Business to ConsumerB2B – Business to Business
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B2C (Business to Consumer)- Social Effects:
Using the Internet, purchasers can go on line to purchase an enormous variety of products and services
B2C commerce is changing traditional business models
Web designers create attractive sites that increase online sales.
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B2B (Business to Business) Social effects
B2B Allows companies to access the Global marketplace (online trading)
The volume of B2B transactions is much greater than that of B2C.
It enables instant information about market prices and availability.
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Consumer to Consumer
C2C - Another innovation is the fact that the Internet can also be used to provide ‘on line auctions’ (Web based providers like EBay form the link between buyers and sellers of all types of personal possessions)
This has proved to be a growth area – there are many on line auctions, but EBay is the most well known.
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Lecture 3 – Systems Development
Lecture 3 introduces the idea of the Systems Development Life cycle
The ‘waterfall’ model is the traditional way to represent structured analysis and design.
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INFO1409 Systems Analysis SDLC L05.ppt
© Copyright De Montfort University 2000All Rights Reserved
Traditional Life Cycle
SystemsInvestigation
SystemsAnalysis
SystemsDesign
SystemsImplementation
Support &Maintenance
FeasibilityStudy
ProjectSelection
“Waterfall” Approach
May have iterations butthese are very costly
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Lecture 4 – User requirements
Lecture 4 looks at the way systems begin from a system request
It explores the reasons for the request and the influences which give rise to it.
It then discusses the preliminary investigation stage of the SDLC
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Systems requests can be the result of both internal and external factors
Page 51 Shelley et al
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Lecture 5 - feasibility
Lecture 5 looks at Feasibility
It explains the different types of feasibility and the reasons for feasibility studies.
The following slide illustrates this:
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Lecture 6 –the systems analyst
Lecture 6 looks at the work of the systems Analyst
It explains the necessary skills and activities that a systems analyst needs to use.
It looks at information gathering techniques used in analysis.
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Activities
Step 2 : Define the Project Scope and Constraints
Determining the project scope means defining the specific boundaries or extent of the project
Some analysts find it helpful to determine the scope by creating a list for example:
MUST DOSHOULD DOCOULD DOWON’T DO
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Step 3 -Perform Fact finding
Fact finding involves various techniques and may consume several hours, days or weeks
Fact finding involves the following: examining organisational charts, conducting interviews, reviewing documentation, observing operations, and conduct a user survey.
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An interview is the primary method of obtaining information (shelley et al p69)
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Lecture 7 –Requirements modelling
Lecture 7 looks at modelling the system to the requirements of the organisation and the user.
It introduces JAD and RAD and OO methodologies.
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(1) Systems Analysis Phase 1 –Requirements modeling
Requirements modelling begins the process
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(2) Joint Application Development
Joint application development (JAD) is a popular fact finding technique that brings users into the development process as active participants.
P93 Shelley et al
Users have a vital stake in the information system and so should participate fully in the development process
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The four phases of the RAD model
Notice the continuous interaction between user design and construction
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Object Oriented methods
This module will expand our understanding of O.O methodology.
Lecture 8 will focus on how CASE tools and Unified Modelling language are part of object oriented analysis concepts.
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Lecture 8 - CASE,UML and OO
Lecture 8 discusses the use of CASE tools
It explains how Unified modelling language is used in Object Oriented methodology.
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Use Case Diagrams
During requirements modelling analysts and users work together to model the system functions
A Use Case diagram visually represents the interaction between Users and the Information system
Use Case diagrams can be drawn freehand, or using Case tools.
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In this diagram the Actor is a customer and the Use Case is a credit validation performed by the system.
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Lecture 9 – Events and Use Case diagrams
Lecture 9 gives advice on identifying and recording the Events that happen in the business process
It gives examples and hints on translating the Events into Use Case diagrams.
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Events Table: hotel booking
Event Trigger
Source
Use Case
Response
Destination
Customermakes booking
customer enquiry
customer
create new booking
room booking confirm-ation
customer and clerk
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Answers1. Customer contacts the hotel for a free
room
2. Clerk checks room availability
3. Customer gives name and address
4. Customer pays deposit
5. Clerk updates system to show room booked
6. Customer rings to order flowers
7. Customer turns up
8. Clerk find room number and gives key
9. Clerk records room as occupied10. Customer leaves
11. Bill calculated
12. Customer pays bill
13 Clerk records room empty and customer paid.
Customer Makes Booking
Customer Orders service
Customer Checks in
Customer Checks out
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Drawing your Use Case
Create new booking
Booking Clerk
Customer
Remember this is just a fragment!!
Illustration