CM5151001 Business Systems Analysis, Design and Construction BSADC

1
CM515100-1 Business Systems Analysis, Design
and ConstructionBSADC

• Week 2

2
What is a System?
3
What is a System?

• A group or combination of interrelated,
  interdependent or interacting elements forming a
  collective entity.
• A functionally related group of elements.
• Systems occur in the natural and man made worlds.

4
Types of Systems?

• Natural Systems
• Stellar systems - Galaxies, Solar Systems
• Biological systems - Blood, Nerves, Lymph
• What others?
• Man Made Systems
• Manufacturing systems - cars, food,
• Financial systems - budgets, accounts
• Administration - Government
• Social Systems - society

5
What are we interested in?

• Systems in organisations that can be analysed and
  modelled.
• This is not a new phenomenon - manual, clerical
  systems
• However, today we expect that these systems can
  be improved by automation through computing.

6
The Automated System Components 1

• Computer Hardware
• processor, disks, workstations, printers,
  scanners
• Computer Software
• operating systems, applications
• Data and information
• stored, processed
• Procedures
• instructions, methods, practices

7
The Automated System Components 2

• People
• Designers
• Programmers
• System Operators
• Those who provide input
• Those who provide output
• Those who use the output
• There are no automated systems without people

8
Types of Automated Information Systems 1

• By application
• Manufacturing
• Accounting and Finance
• Personnel
• Military
• Command and control
• Computers are everywhere in business

9
Types of Automated Information Systems 2

• By Broad Class, for example
• Data and processing systems
• usually payroll - lots of standard transactions
• Office Support Systems
• Word processing, Email, DTP
• Decision Support Systems
• Spreadsheets, Executive systems
• Expert systems and Artificial intelligence

10
Final thoughts on Systems

• Computer Information Systems have radically
  changed the way we live and work
• The systems in place today are sophisticated and
  technically intricate
• They have complex structures
• They are complex because they model complex
  systems and situations
• Hence the need for systems analysis

11
What is a Analysis?
12
What is a Analysis?

• Analysis
• The division of a physical or abstract whole into
  its constituent parts...........
• to define, examine or determine their....
• nature, proportion, function or relationship.

13
From our point of view 1

• Analysis - understanding
• The study of a problem prior to taking some
  action - T. DeMarco.
• Understanding the essential underlying nature of
  an activity (activities)
• Building a model of the activity as it is now in
  writing and/or graphically

14
From our point of view 2

• Analysis - improving
• Determining how an activity might be made more
  efficient
• firstly without computing
• secondly with computing
• Building a model the activity that incorporates
  the proposed improvements
• Determining what is achievable

15
In summary

• We can say that systems analysis is
• The analysis of processes and information systems
  in organisations.........
• which may lead to the development of computer
  based systems........
• to augment or replace existing systems, manual or
  primitive computer systems.
• Systems Analysts role is to give clarity to
  complex situations

16
From this to that?
17
Who does analysis?

• Systems Analysts
• System Designers
• Programmers
• Management
• Auditors
• Operational staff
• USER - but who is the user?

18
Who is the User?

• User can be defined in three broad classes
• The System Owner
• The System User
• The Hands-on User

19
The System Owner?

• Commissions the Systems
• Finances development
• Formally accepts the system
• May be an
• individual,
• committee or
• Board of Directors

20
The System User?

• Holds the knowledge of the new requirements
• Knows what is acceptable in terms of performance
  and serviceability
• likely to be departmental manager or supervisor
• has a general familiarity with the operation
• driven by budget considerations

21
The Hands-on User?

• Uses the new system - face to face
• Has to adapt to changes brought about by the new
  system
• always has a local and hands-on view
• carries out a the function of the system
• has a physical view

22
The Systems Analyst

• Just like Dilbert
• Investigator
• Diplomat
• Innovator
• Communicator
• Project leader

23
Methodology, Methods, Tools and Techniques
24
Aims and Objectives

• Aim To give you an understanding of
  methodologies, methods, tools and techniques
• Objectives After studying this weeks material
  you should be able to describe
• Software development methodologies
• Methods, tools and techniques used in a
  methodology
• The Software Development Life Cycle - SDLC

25
Developing Software

• Software Projects vary in size and complexity
• Database for a sports club 1 or 2 people
• Payroll system 10 to 20
• Inventory System 30 to 40
• Microsoft Office 1000s
• Without a coordinated approach to development -
  chaos would ensue

26
Approaches to building a home

• Buy a plot of land
• Get it built, how?
• Do it yourself, or
• Get a builder, or
• Get an architect
• Move in
• Which approach above is more likely to get you
  the home you want?

27
Is Developing Software the same?

• This what it is all about (avoiding)

28
What is Methodology?

• Methodology is
• A formalised approach to software development
• a set of sequential stages
• Each stage has methods, tools, techniques and
  techniques associated with it
• A specification of how systems will be developed
• There are many different methodologies

29
Spiral Model
Evaluate alternatives, identify, resolve risks
Cumulative cost
Progress through steps
Determine objectives, alternatives, constraints
Risk Analysis
Risk Analysis
Operational Prototype
Risk Analysis
Prototype 3
Prototype 2
Risk Analysis
Prototype 1
Commitment Partition
Simulations Models, Benchmarks
Requirements plan Lifecycle plan
Concept of operation
Software requirements
Requirements Validation
Development plan
Software product design
review
Integration and test plan
Code
Design validation and verification
Unit test
Acceptance test
Integration test
Implementation
Plan next phases
Develop, verify next-level product
30
V Model
Project Initiation
Requirements specification
Product phase out
Evolution
Acceptance testing
Detailed requirements specification
Specification
Verified System
Architectural software design
System Integration test
Integrated software
Design
Software Integration test
Detailed software design
QA
QA
Debugged Modules
Module Design
Code Unit test
31
Soft Systems Methodology
action to improve situation
1
7
Problem situation
problem situation expressed
desirable and feasible changes
2
6
5
compare models and real world
root definitions
3
REAL WORLD

• SYSTEMS WORLD

conceptual models
4
32
Waterfall Model
System Feasibility - Validation
Software plans requirements - Validation
Product Design - Verification
Detailed Design - Verification
Code - Unit test
Integration - Product verification
Implementation - System test
Operations Maintenance - Revalidation
33

• There is a whole module on this at level 3
• We will focus on the SDLC

34
System Development Life Cycle
35
Categorising Methodologies

• Data centred methodology
• Focus on how to structure the contents of data
  stores
• Process centred methodology
• Represents how a business system operates
• Documents he processes and how data moves between
  them
• Object oriented methodology
• Attempts to balance the focus between data and
  process

36
What will you study?

• Structured Systems Analysis using the SDLC
• Process Methodology
• Data Flow Diagrams
• Entity Relationship Diagrams
• Entity Life History
• Entity/Event Matrices
• Dont worry about these terms for now

37
Structured Analysis in more detail

• What is Structured Analysis?
• A set of tools to build a model of the system
• A set of techniques to use the models
• A way of avoiding communication problems
• Why is it needed?
• Systems today can be huge - it is impossible to
  write a single specification for the whole system
• Structured analysis enable the system to be
  broken down into smaller mini-systems

38
The need for methodology in more detail

• Establishes a style procedure
• the way a system is developed from new, or the
  way an existing system is enhanced or amended
• Establishes a consistency of approach
• a list of activities needed
• an order for the activities required
• Establishes Management Control
• milestones, checkpoints
• Encourages quality of product

39
Formal Methodologies

• The most common used in government and large
  organisations
• Structured Systems Analysis and Design
  Methodology - SSADM
• There are many more methodologies

40
Methods, Tools and Techniques

• Investigation Methods
• Observation
• Examination of documents
• Interviews
• Questionnaires
• Diagramming Techniques
• Data Flow Diagrams
• Entity Relationship Diagrams
• Entity Life History
• Entity/Event Matrices

41
Feasibility Report Stage

• The feasibility study is your end of semester
  assignment
• The feasibility report will bring together many
  of the Methods, Tools and Techniques
• More about the feasibility study/report later in
  the semester

42
Remember This

• This what it is all about (avoiding)

43
Self study this week

• Essential Reading
• Read Mastering Systems Analysis and Design -
  pages 6 to 15
• Do exercises 1.7.1 to 1.7.10
• http//www.cems.uwe.ac.uk/tdrewry/Lifecycl.htm
• More help
• http//www.umsl.edu/sauterv/analysis/analysis_lin
  ks.html
• http//blogs.ittoolbox.com/pm/minimalit/archives/w
  hat-is-a-system-22699

44
Workshop this Week

• Video The Great IT Horror Story

45
Next week Week 3

• An introduction to investigation methods