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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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Components of an Information system

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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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Six of the main reasons for Systems requests

P51 Shelley et al

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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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We will examine each of these in turn in the following slides

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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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Definition of a CASE environment by Carnegie Mellon

From Shelley et al

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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

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Recommended Reading

The set text for this module isSystems Analysis & DesignShelley Cashman & Rosenblatt (6th or 7th Ed)Thomson Course Technology (2006)ISBN 0-619-25510-2Your reading should also be

supplemented by the other references listed at the end of lectures.