Analysis and Design Phases

1
Analysis and Design Phases

• Taken from the Software Development textbook
• Chapter 3
• M. Sanchez

2
How much do you know?

• Information Systems?
• Types of Information Systems? Their purpose?
• Goals?
• Objectives?
• Mission statement?

3
The purpose of information systems

• Serves organisations
• Aims and objectives directly related to the IS
• A mission statement describes the organisations
  reason for existence, its focus and direction
• Organisations are groups of people working
  together towards a common goal
• The operational objectives determine the size and
  type of IS
• Operational goals concerned with the efficiency
  and effectiveness of the operations of the
  organisation

4
Have you learned?

• Analysis and Design worksheetQuestion 1-5

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The purpose of information systems

• An information system can aid in the achievement
  of an efficient operation of an organisation
• An IS can reduce
• the cost of processes in the production of
  services and goods
• Amount of effort taken by staff
• Time taken to complete essential activities
• An IS can aid in the achievement of an effective
  operation of an organisation (better quality
  products and services)

6
Problems in organisations

• Two types of problems
• An immediate problem that prevents a product or
  service being provided adequately.
• A person can have an idea that will enable the
  aims and objectives to be better achieved.
• An information system analysis has to be
  undertaken when problems arise.

7
Other Change Factors

• These factors often impose limitations and
  constrains on the design of the new system too
• What other factors do you think would prompt for
  a change in IS?

8
Factors

• Technical
• Economic
• Social and organisational
• Legal and financial
• Security and access factors
• Health and safety

9
Technical Factors

• Many transactions need to be processed each
  day.Examples
• TAB betting system
• Stock market systems
• Banking systems
• Reliability
• Robustness
• Size of the network
• Local processing
• Type and amount of data
• Legacy systems
• Maintainability
• Usability

• Reliability
• Few breakdowns
• The equipment will need to have redundancy built
  in (Fault tolerant systems)

• Robustnes
• Operate in different physical conditions

• Network size
• Mainframe as a server if too many nodes.
• System needs to be scalable

Local processing If amount of processing small
then only terminals could be required.

• data
• Software and hardware will vary depending on the
  type of data

Legacy systems Keeping the old systems

• Maintainability
• Grow according to organisations changing needs
• Changes to hardware and software should be easily
  implemented

Usability Easy to use and simple to navigate
and straightforward
10
Economic Factors

• Initial cost in the selection of a designfor a
  system
• Ongoing cost
• Equipment upgrades and repairs
• Cost of training and paying staff to run the
  system

11
Social and Organisational Factors

• The needs of the user determine much of the
  design of an IS
• The design should concentrate on the users needs
  rather than the processing and storage
  requirements

12
Legal and Financial Factors

• In financial systems, the legal and accounting
  requirements can affect the way the system
  operates and its design.
• There is a growing need for organisations to be
  able to communicate online (e-commerce)
• There are also various legal requirements
  covering accounting and privacy matters. Back up
  and archiving procedures and equipment need to be
  taken into account.

13
Security and Access Factors

• Logon names and passwords
• Encryption
• Biometric security
• Keeping logs of activities
• Surveillance cameras
• Keys for locks
• Smart cards
• RFID transponders
• guards

14
Security and Access Factors

• Backup Security
• A standard four week backup plan
• Daily tape backups (reused each week)
• Separate weekly tape backups reused monthly)
• A monthly tape backup kept as permanent record

15
Security and Access Factors

• Disaster Recovery Plans include
• Emergency power supply
• Emergency procedures in case of fire, storms or
  natural disasters
• Plans for replacement of or access to other
  computers and equipment
• Procedures for restoring the data from backups
  stored in a safe place
• Testing of the recovery procedures similar to a
  fire drill

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Social Factors

• All IS exist within a social context.
• Considerations
• Language
• Audience
• Purpose
• Each organisation has its own culture that
  affects the design of IS and the flow of data and
  information.

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Health and Safety Factors

• Ergonomics arrangements
• The use of voice recognition and voice production
  software
• Use of robots and computer-controlled equipment
  in dirty and dangerous situations

18
Organisational Requirements

• Many organisational factors can cause problems
• Number and location of branches
• Types and conditions of buildings
• Need to travel
• Telecommunicating

19
Have you learned?

• Analysis and Design worksheet
• Question 6

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Defining the Problem

• Exact problem has to be defined
• A preliminary investigation is performed
• The original problem is put in a negative form as
  it describes why a solution needs to be found.
• Positive problem statements describe what needs
  to be done to fix the problem (It implies the
  goal/s to be achieved).
• How do you think we can find the causes of the
  problem?

21
How much have you learned?

• Analysis and Design worksheet
• Answer questions 7a, 7b and 7c

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Possible solutions

• A feasibility study of the proposed solutions
  should be carried out.
• Is the solution worthwhile?
• Is the solution practical?
• Three aspects to consider in the feasibility
  analysis are
• Operational feasibility
• Technical feasibility
• Economic feasibility

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Possible solutions

• Operational Feasibility
• Whether a project can be put into place.
• How will people be affected.
• Whether unintentional effects may occur as a
  consequence of the change
• Legal and ethical issues are addressed
• Effects on employment
• Implementation schedules

24
Possible solutions

• Technical Feasibility
• Characteristics of the required hardware and
  software
• Scalability for future needs
• Reliability of the equipment
• Whether the resources to operate the system exist
• Availability of components

25
Possible solutions

• Economic Feasibility
• If the new system is a good investment.
• It will be feasible if benefits are more
  important than the costs of installing, planning,
  purchasing and building it.
• The cost elements evaluated may include
• Personnel
• Software licensing
• Training
• Development of custom-software
• Cost of hardware

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Choosing a solution

• A decision will be made based on the study
• A feasibility report will be written presenting
  the consequences and benefits of the proposed
  solutions and the reasons for the final choice.
• When the decision is made to proceed with the IS,
  limits and constrains are set on the system. It
  can include
• Money available
• Time line of the project
• Limitations of the changes within the
  organisation
• Links between the new and old system

27
Case study

• Ceep Kool case study

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Analysis Phase

• A detailed analysis of the old system is the
  basis for the design of the new one.
• A logical design contains
• The broad aims and objectives of the new system
• Major system components description
• It is the basis of the physical design stage

29
Analysis Phase

• A development team is selected, generally the
  Information System Department, user managers and
  potential system users.
• The team is lead by a professional system analyst
• Data is gathered using a number of techniques
  and analysed using a range of tools that will
  specify the data used, the information produced
  and the processes used to transform data into
  information.

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Data Collection Techniques

• It will come from documents and people associated
  with the IS, and people not directly linked to
  the IS Customers and senior management.
• Interviews
• Observation
• Surveys
• Collection of documents and files
• Research into similar and replacement systems

31
How much have you learned?

• Answer questions 8 and 9

32
Tools used to describe IS

• Two types of data are collected from the IS for
  the analysis
• Application data
• Background data
• Once collected, background data needs to be
  processed and manipulated by the development team
  to produce information.

33
Tools used to describe IS

• The system analyst uses a number of tools to
  focus on three aspects of the system
• Logical operations involving data/information and
  the movement of data/information
• The processing of data into information
• The relationship between physical components of
  the information system.

34
Tools used to describe IS

• Tools for analysing and documenting the logical
  operations of an IS are
• CD
• DFD
• Data dictionaries

35
Tools used to describe IS

• Tools for analysing and documenting the
  processing of data and information are
• Flowcharts
• Decision tables
• Decision trees
• Grid charts
• Structured English
• IPO charts
• Processing centre descriptions

36
Tools used to describe IS

• Tools for analysing and documenting the
  relationship between the physical components of
  an IS, both hardware and software, are
• Hierarchy charts
• Structure charts
• System flowcharts