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ACS-1803 Introduction to Information Systems

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ACS-1803 Introduction to Information Systems Instructor: Kerry Augustine The Development of Information Systems Lecture Outline 14 ACS-1803 Introduction to ... – PowerPoint PPT presentation

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Title: ACS-1803 Introduction to Information Systems


1
ACS-1803Introduction to Information Systems
  • Instructor Kerry Augustine

The Development of Information Systems Lecture
Outline 14
2
Principles and Learning Objectives
  • Understand the process used by organizations to
    manage the development of information systems
  • Describe each major phase of the system
    development life cycle systems identification,
    selection, and planning system analysis system
    design system implementation and system
    maintenance
  • Understand the factors involved in building a
    system in-house, along with situations in which
    it is not feasible

3
Systems Development
p. 354 - 392
4
Systems Development
- sometimes, a system that is needed by a
business is not available as a 'canned' system
which can be bought and installed - such a
system must be custom-built either by systems
developers in-house or by external consultants
5
System Development Life Cycle L
  • usually a system is developed in specific SDLC
    stages
  • 1. Systems Investigation
  • a) Problem Definition
  • b) Feasibility Study
  • 2. System Analysis
  • 3. System Design
  • a) General Design
  • b) Detailed Design
  • 4. System Development (Building)
  • 5. System Implementation
  • 6. System Maintenance
  • Stages not necessarily linear

6
System Development Life Cycle
  • Systems investigation
  • Identifies problems and opportunities and
    considers them in light of business goals
  • Systems analysis
  • Studies existing systems and work processes to
    identify strengths, weaknesses, and opportunities
    for improvement
  • Systems design
  • Defines how the information system will do what
    it must do to obtain the problems solution

7
System Development Life Cycle
  • Systems development
  • Creates or acquires various system components
    detailed in systems design, builds/assembles for
    implementation.
  • Systems implementation
  • Places new or modified system into operation
  • Systems maintenance and review
  • Ensures the system operates as intended
  • Modifies the system so that it continues to meet
    changing business needs

8
System Development Life Cycle L
  • usually a system is developed in specific SDLC
    stages
  • 1. Systems Investigation
  • a) Problem Definition
  • b) Feasibility Study
  • 2. System Analysis
  • 3. System Design
  • a) General Design
  • b) Detailed Design
  • 4. System Development (Building)
  • 5. System Implementation
  • 6. System Maintenance

9
System Development Life Cycle L
  • Systems Investigation
  • ltshould we really develop a new system?gt
  • - identify problems with the current system and
    opportunities for improvement
  • why do we want a new system?
  • do initial feasibility study for the proposed
    system L
  • - financial feasibility (is available)
  • - technical feasibility (is equipment available)
  • - operational feasibility (will people be able to
    work with new system)
  • if we determine that a new system is feasible,
    we go on to the next stages

10
Systems Investigation
System Identification A process used to identify
opportunities for developing systems projects to
solve problems. This process varies greatly from
organization to organization
Selection The process of applying evaluation
criteria to possible projects to select those
that are critical to enabling the organizations
mission, goals, and objectives
Systems Planning Developing formal plans for
creating the information systems project
selected. Some organizations call their periodic
process of identification, selection, and
planning Information Systems Planning (ISP)
11
Systems Investigation
Criteria for evaluating and selecting a systems
project
12
System Development Life Cycle L
  • usually a system is developed in specific SDLC
    stages
  • 1. Systems Investigation
  • a) Problem Definition
  • b) Feasibility Study
  • 2. System Analysis
  • 3. System Design
  • a) General Design
  • b) Detailed Design
  • 4. System Development (Building)
  • 5. System Implementation
  • 6. System Maintenance

13
System Development Life Cycle
  • System Analysis L
  • - analyze the current information system (manual
    or computerized), in terms of data, processing
    and information flow, and user input/output
  • - ask where are problems with the current system
    or what other reasons are there to develop a new
    system
  • we get an idea of WHAT will be required of the
    new system in terms of data, processing, and user
    interfaces we document this in detail

14
System Analysis
  • We now look at analysis in more detail
  • After the preliminary investigation, if the
    system proposal is found to be feasible, a
    detailed analysis is carried out
  • For the current system
  • For the requirements of the new system

15
Systems Analysis (contd)
  • - A systems analyst can use different ways of
    gathering the information on system features and
    requirements L
  • Current system documentation
  • Sampling outputs and input forms from current
    system
  • Observation apprenticing with a user
    videotaping people using the system
  • Administering questionnaires
  • Interviewing users

16
Systems Analysis (contd)
17
Systems Analysis (contd)
  • Collecting System Requirements (Traditional)
  • A combination of methods are used
  • Interviews discussions with stakeholders (i.e.
    users)
  • Questionnaires surveys to assess use and
    attitudes
  • Observations watch process and systems use
  • Document Analysis reviewing current documents
  • Collecting System Requirements (Alternative)
  • A combination of traditional methods are used
  • Critical Success Factors (CSFs) a process of
    interviewing, recoding, analyzing and merging
    factors defined as critical by personnel at all
    levels of an organization
  • Joint Application Design (JAD) - a method that
    brings together users and analysts in a room to
    define requirements. This method greatly reduces
    design time

18
Systems Analysis - Critical Success Factors
19
Systems Analysis - Joint Application Design
  • JAD is a special type of a group meeting in which
    all (most) users meet with an analyst at the same
    time
  • Users jointly define and agree upon system
    requirements or design dramatically reducing the
    design time

20
Documenting System Requirements MC
  • What has been discovered through the above
    techniques needs to be documented adequately
  • Can use English descriptions, but then will need
    to use structured diagrams
  • Might use traditional diagrams (data flow diagram
    and program structure chart)
  • OR, may model entire system as a set of
    interacting objects (OO object-oriented)

21
System Analysis Modeling Organizational Data
The Entity Relationship Diagram (ERD) A tool used
to identify the relationships between entities to
assist in developing applications and databases
22
Two Ways of Diagramming for Analysis and Design
MC
  • 1. The Traditional Structured way
  • Data and programs designed separately
  • For data entity-relationship diagrams
  • For programs
  • Start with data flow diagram in analysis
  • This becomes the program structure chart in design

23
The Data Flow Diagram DFD
  • Uses only 4 symbols
  • square (external entity)
  • Curved arrow (data flow)
  • Open ended rectangle (data store)
  • Circle (process)

24
Data Flow Diagrams (DFDs)
  • Data flow diagram (DFD) is a picture of the
    movement of data between external entities and
    the processes and data stores within a system

25
Two Ways of Diagramming for Analysis and Design
MC
  • 2. The object-oriented way of doing analysis and
    design
  • Data and programs encapsulated in structures
    called OBJECTS
  • There are prescribed diagrams for analysis and
    design which are part of the Unified Modeling
    language (UML)

26
An Object
  • a structure that has BOTH attributes (variables,
    properties) and programs (methods) that act on
    these properties
  • in an object, the attributes and programs are
    encapsulated

27
Example a Customer Object
  • - attributes customerNo., name, address,
    phoneNo. creditLimit
  • - programs acceptCustomer() assignCreditLimit(ye
    arlyEarnings)
  • deleteCustomer(customerNo)

28
Object-Oriented Analysis and Design
  • We will see what diagrams are used for a new
    system, as part of the Unified Modelling Language
    (UML)
  • Use case diagrams
  • What is needed in the new system is derived from
    what we will use the system for
  • Object class diagrams
  • - What main items will we keep data on?

29
Prescribed Diagrams
  • When developing a new system in the object
    oriented way, the system development team uses
    specific diagrams in the Unified Modeling
    Language (UML)
  • - use case diagrams (how system will be used)
  • - object class diagrams (database files)
  • - Sequence diagrams (order of processing)
  • From these diagrams we will know how to set up
    our database and how to write the programs for
    the new system.

30
Use Case Diagram for Video Rental Store
31
Class Diagram for withdrawal of cash, normal
flow
32
Sequence Diagram for withdrawal of cash, normal
flow
1. Insert card Enter password, Enter kind Enter
amount, Take cash, Take card cancel,Terminate,
Continue
Create Transaction Transaction complete
Display main screen unreadable card
message, request password, request kind, request
amount, canceled message, eject card, failure
message, dispense cash, request take cash request
continuation, print receipt, request take
card bad account message, bad bank account message
Transaction succeed Transaction failed account
o.k. bad account, bad password, bad bank code
Verify account, process transaction
33
Design of other system components
  • The UML diagrams helped us to design the database
    and programs for the new system
  • We also have to design menus, input screens,
    output screens, reports, system controls,
    hardware and telecommunication plans,
    organizational aspects

34
System Development Life Cycle L
  • usually a system is developed in specific SDLC
    stages
  • 1. Systems Investigation
  • a) Problem Definition
  • b) Feasibility Study
  • 2. System Analysis
  • 3. System Design
  • a) General Design
  • b) Detailed Design
  • 4. System Development (Building)
  • 5. System Implementation
  • 6. System Maintenance

35
System Development Life Cycle
36
System Design MC
  • Detailed design for
  • Database
  • Programs
  • Menu, input, output screens, reports
  • Controls
  • Hardware telecomm
  • Organizational aspects

37
System Design - Designing Forms and Reports
Forms - a business document with predefined data
and places to fill in information that is used
for system input
Reports a system output that contains only
predefined data usually in a tabular format (see
below)
38
System Design - Designing Interfaces and Dialogues
User Interface Example Govt of Alberta
39
System Design - Designing Databases and Files
40
After system design, L
  • Programmers code programs that belong to each
    object class
  • Programs are tested and loaded onto disk
  • Database personnel set up the database on the
    disk of the server
  • System is implemented
  • Users are trained
  • System is in regular use

41
System Development Life Cycle L
  • usually a system is developed in specific SDLC
    stages
  • 1. Systems Investigation
  • a) Problem Definition
  • b) Feasibility Study
  • 2. System Analysis
  • 3. System Design
  • a) General Design
  • b) Detailed Design
  • 4. System Development (Building)
  • 5. System Implementation
  • 6. System Maintenance

42
System Development Life Cycle
43
System Implementation Programming and Testing
Software Programming creating the instructions
from the programming logic design using a variety
of programming languages often assisted by
language editors
Software Testing a series of tests designed to
identify errors and validate logic in parallel
with programming. There are multiple types of
testing (see below)
44
System Implementation System Conversion
Conversion Approaches the process of taking
information from an old system to populate a new
system. This is accomplished through manual
and/or automated methods
45
System Implementation System Documentation
System Documentation The collection of materials
produced with an information system to support
the ongoing operation and development
  • Documentation Types
  • User and reference guides step-by-step
    instructions for using the system features and
    functions
  • User training and tutorials manuals and
    exercises designed to educate users and build
    competence in system use. These training manuals
    and tutorials can be supported by a database that
    utilizes realistic data
  • Installation procedures and trouble-shooting
    suggestions manuals and procedures designed to
    support technical personnel in installing and
    problem solving during system operation

46
System Implementation System Training
Training Approaches the processes used to
educate users in new business processes and
system features and functions with the goal of
building competence to ensure operational success
(see possible methods below)
47
System Maintenance - Maintenance Types
System Maintenance The process by which a system
is kept in working order and minor enhancements
are completed. Some types of system maintenance
are shown below
48
Needs for Alternatives to Internal Systems
Building
Often it is not feasible to consider building an
information system internally. Below are four
situations that discourage the idea of internal
development
Limited IS Staff Limited IS Skill Sets IS
Staff is Overworked Problem IS Performance
The IS organization does not have the
capability to build the system itself The IS
organization does not have personnel with the
correct skill sets to build the system Current
IS organization staff demands and priorities make
it impossible to build a system The IS
organization does not have the appropriate
performance level to build a system
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