Systems Analysis CSCI 308

1
Systems AnalysisCSCI 308

• Instructor Stan Schuyler
• Lecture 2
• The Context (Domain) of Systems Analysis and
  Design

2
Topic Outline

• Terminology concepts interspersed
• Brief History the evolution of SAD
• SAD Systems Analysis and Design
• What does a disciplined approach mean?
• What is
• data-centricity?
• process-centricity?
• SAD on SAD What models are used to describe
  Systems Development?
• Working on Teams

3
Systems Analysis and Design

• What is a Domain?
• Domain Subject Area Taxonomy Relationships
• Taxonomy hierarchical list of categories (e.g.
  an outline)
• Relationships described dependencies,
  inheritance
• Subject Area Usually a Type of Business Problem
• Finance / Accounting
• Supply/ Distribution/ Logistics
• Production/Operations
• Etc.
• Relationships Organizational Objectives
• SCOPE of Problem/Solution
• Timing (timeliness)
• BUDGET / COST
• More Relationships Culture of the organization

4
History of SAD

• Domain of Military Organizations
• War motivated military science across the ages
• World War II Expanded Military Science
  applications
• Encryption/Decryption Technology
• Radar and fire control systems
• ACBMS (Safeguard) Development in the 1950s
• Bell Labs Codifies Total Systems Development
  (TSD) in the early 1960s
• Applied to the domain of NASA Space Programs
• Used for Large Scale Software Systems
• The methodology was Process-Centric
• That means ?Activity Focused
• Functional Decomposition

5
Process Centric (Functional Decomposition)

• Function A ()
• Function A1()
• Function A2 ()
• Generic Function Z()
• Function A3()
• Fcn A31()
• Fcn A32()
• Function A4()
• Function B()

output
outputs
6
History (cont)

• Problems
• Process (activity) emphasis missed many target
  system requirements related to data requirements
• Solutions - Sequencing and flow unique to
  designers framework, difficult for newcomers to
  learn.
• Data-Centric Methods introduced in the 1980s
• Work products
• What is produced (output)
• What is consumed (input)
• States and Relationships Specified
• Object Oriented Design

7
Transition Data Flow Diagram1
1. Wikipedia, Data flow diagram ,
en.wikipedia.org/wiki/Data_flow_diagram,
downloaded 8/23/09.
8
Work Product (Data) Centric Model
9
Standardized Data Flow Diagram ibid
ibid. Wikipedia, Data flow diagram ,
en.wikipedia.org/wiki/Data_flow_diagram,
downloaded 8/23/09.
10
Enhanced Std. Data Flow Diagram ibid
ibid. Wikipedia, Data flow diagram ,
en.wikipedia.org/wiki/Data_flow_diagram,
downloaded 8/23/09.
11
Approaches Compared
What data does the system produce?
ltMeta-datagt describing output and/or input
formats is constantly changing
12
What do we Mean A Disciplined Approach

• Methodologies
• A multi-discipline, multi-step approach to the
  analysis, design, and delivery of an IS
• Techniques
• Procedures that, when followed, increase the
  utility of analysis work products (accuracy,
  scope, and clarity)
• What and How to Observe?
• What and How to Measure?
• How to Analyze (Qualitative, Quantitative)
• Inference
• Synthesis
• Tools
• Usually computer automated techniques
• Low Tech Word, Excel
• Higher Tech CASE

13
Define System

• A System is a
• Set of people and procedures (possibly automated
  components), organized in such a way as to
  accomplish a set of stated objectives.
• Analysis means
• To examine a situation, circumstance, or event
  and decompose it into its components and
  dependencies in order to identify problems or
  opportunities for improvement.
• To identify and categorize elements, components
  and relations observable in a situation.
• To synthesize the whole from the modeled
  components

14
Systems Analysis and Design

• Definition of SAD Textbook
• A structured process that is employed in the
  development of information systems
• Systems analysis activities
• Systems design activities
• Definition of Your SAD Professor
• An analysis framework that contains a pattern of
  questions and modeling techniques that are used
  to produce work products necessary to change a
  system
• Produce a Problem Statement Description
• Produce a External System I/O Requirements
  Description
• Produce a System Architecture Description
• Produce a High-level Design Description

15
Meta-Process

• System Analysis, Design and Development is a
  Domain that can be studied like any other problem
  space.
• To describe it you need to use language
• A process to describe a process a Meta Process
• SDLC Systems Development Life Cycle
• It is a meta-process
• TSD (Bell Labs) is a meta-process
• Often referred to as a Waterfall Model of
  Systems Development
• SDLC
• Composed of a common set of phases and activities
  that serve to structure and guide the development
  process

16
SDLC Model (aka. the Waterfall Model)
Your Textbook
17
Figure 1-6. WHY? Look at the relative cost of
fixing an error in a development project!
18
There is Always a Situation and Circumstance
within which we work
Problem Solution State Network
19
The Business of Business

• Most business operations are conducted by Systems
  (people, procedures )
• Most Systems Development Work is accomplished by
• Multiples of individuals
• Assigned to teams
• Organized in functional business function units
  in such as way as to
• And this fact is the basis for Assignment 3B
• A few words about Assignment 3B
• The Profile Download

20
Supporting Terminology Definitions
21
A Hierarchy of Terms

• What is Data?
• Symbols or signs
• Something that stands for something else that
  people can perceive and produce.
• Data
• symbols in a form a computer can input, process
  and output
• What is Information?
• symbols in a form that allow people to share
  meaning it is symbols or signs that have been
  interpreted to mean something else.
• What is Knowledge?
• Information (meaning) that explains the how?
  and why? of something else.

22
Then What is?

• What is Information Technology?
• Technology (hardware, software, connectivity)
  that can be configured into a system to process
  and transport data, representative of symbols and
  signs that people interpret, effectively.
• Oracle Database Components
• What is an Information System?
• A system that is organized to process data,
  representative of meaning units shared , in
  ways compatible with and meaningful to a
  community, to achieve a specified set of
  objectives.
• The classroom is an Information System

23
And What are?

• An Information Management System?
• An information system designed to enter, edit,
  coordinate, and produce data and information to
  achieve the designated, shared, objectives of a
  specific organization, organization type, or
  team.
• SAP
• CASE
• A Knowledge Management System?
• An information systems designed to enter, edit,
  coordinate, and make inferences as to how and why
  data interpreted as information are related in a
  specific domain
• Expert Systems, Artificial Intelligence

24
Other Related Terms (signs)?

• What is a Learning Set
• Learn how you learn
• Information that reveals how you discover
  knowledge
• What is Problem Solving
• A process of questioning to resolve or improve a
  situation
• A process of discerning causation from symptoms
  of problems to formulate one or more problem
  statements
• A process of formulating one or more solutions
  from a set of problem statements

25
SDLC Terminology Clarifications

• Preliminary investigation phase
• Identification and selection of a development
  project
• Initiation of a preliminary investigation to
  determine project feasibility
• Formation of a project team
• Development of the project plan

26
Overview of Phases and Activities

• Analysis Phase
• Study of the organizations processes,
  procedures, and systems
• Logical Design Phase
• Revise and refine the logical model ? ???
• Implementation independent

27
Overview of Phases and Activities

• Physical Design Phase
• Convert logical model into physical model
• Implementation specific
• Implementation Phase
• Installation of the actual physical system
• End user training
• Maintenance Phase
• Detailed modifications to the new system
• Cycle through all the above phases