Chapter 11 - Managing Systems Implementation

Learning Objectives

• Explain quality assurance and three techniques to improve the finished product
• Outline application development
• Apply structured development
• Apply object-oriented development
• Apply agile development
• Explain coding
• Explain unit, integration, and system testing
• Differentiate between program, system, operations, and user documentation
• Explain the role of online documentation
• Describe the five tasks involved in system installation

1. Quality Assurance (QA)

• Companies in a competitive environment are intensely concerned with product/service quality
• Objective: avoid problems, or identify them as early as possible
• Poor quality can result from:
  • Inaccurate requirements
  • Design problems and coding errors
  • Faulty documentation and ineffective testing

เหมือน QC ในโรงงาน — ถ้าพบ bug ตั้งแต่ต้น ค่าซ่อมถูกกว่าพบตอนส่งมอบ

1.1 Software Engineering

• Application of engineering principles to the creation of complex, long-lived applications
• Software Engineering Institute (SEI) at Carnegie Mellon University
  • Provides quality standards and suggested procedures

1.2 Capability Maturity Model (CMM)

• Aims to improve software quality, reduce development time, and cut costs
• Has 5 maturity levels:

CMM เหมือน belt ใน Judo — ระดับขาว (Initial) ถึงระดับดำ (Optimizing) ยิ่งระดับสูง กระบวนการยิ่งมีระเบียบ

1.3 Systems Engineering

• Builds upon software engineering
• Includes other parts of the overall system: hardware, networks, interfaces

1.4 ISO Standards

• International Organization for Standardization (ISO): establishes internationally recognized quality standards
• ISO 9000-3:2004: provides a QA framework for developing and maintaining software
• ISO standards can be:
  • Specified when purchasing software
  • Used to guide in-house software development efforts

2. Application Development

• Definition: process of constructing the programs and code modules that serve as the building blocks of an information system
• Objective: translate the design into program/code modules that function properly
• Development options: Structured analysis, Object-Oriented (O-O) analysis, Agile methods

เหมือนการก่อสร้างบ้าน — design เสร็จแล้วต้องแปลงแบบเป็นอิฐ คาน หลังคา (modules) ที่ทำงานร่วมกันได้จริง

2.1 Reviewing the Systems Design

Tasks involved in creating systems design:

• Break down complex business operations using Functional Decomposition Diagrams (FDDs)
• Create Data Flow Diagrams (DFDs)
• Develop an object-oriented model of the new system
• Select a development strategy
• Design the user interface
• Construct Entity-Relationship Diagrams (ERDs)
• Consider an overall system architecture

2.2 Application Development Tasks (Traditional)

• Plan: Overall Planning
• Develop: Design → Code → Test → Document (individual modules)
• Test: Integration Testing → System Testing
• Document: Final Documentation

2.3 Agile Methods

#FinalExam ถาม Definition ของ Agile (ต้องมีคำว่า iterative)

• Objective: create a system through an iterative process of planning, designing, coding, and testing

Flow: Concept → Preparation → Release Planning → Iteration → Acceptance Tests → Release

• Loops back for new iterations and new user stories

2.4 Systems Development Tools

• Entity-Relationship Diagrams (ERDs): show interaction among system entities/objects
• Flowcharts: represent logical rules and interactions graphically
• Pseudocode: describes program actions implementable in any language
• Decision tables and decision trees: model business logic for an information system

Example — Sales Promotion Policy (Pseudocode)

IF customer is a preferred customer, and
    IF customer orders more than $1,000 then
        Apply a 5% discount, and
        IF customer uses our charge card, then
            Apply an additional 5% discount
    ELSE
        Award a $25 bonus coupon
ELSE
    Award a $5 bonus coupon

Example — Decision Tree (same policy)

Preferred customer?
├── Y → Ordered more than $1,000?
│        ├── Y → Used our charge card?
│        │        ├── Y → 5% discount + additional 5% discount
│        │        └── N → 5% discount only
│        └── N → $25 bonus coupon
└── N → $5 bonus coupon

3. Structured Development

เหมือนการ decompose function ใหญ่ใน Swift ออกเป็น smaller functions — แต่ละ module ทำหน้าที่เดียว

3.1 Partitioning

• System is broken down into subsystems and modules

3.2 Structure Charts

• Display program modules and relationships
• A module is represented by a rectangle
• Types of modules:
  • Control module: higher-level module (the "boss")
  • Subordinate module: lower-level modules (the "workers")
  • Library module: reusable code (double-sided box)

3.3 Structure Chart Notation

3.4 Cohesion and Coupling

• Cohesion: measures a module's scope and processing characteristics
  • A module that performs a single function has high cohesion ✅
  • High cohesion = good design
• Coupling: describes the degree of interdependence among modules
  • Loosely coupled: modules are independent ✅ (preferred)
  • Tightly coupled: one module is linked to internal logic of another ❌ (avoid)

Cohesion เหมือน Single Responsibility Principle ใน iOS — ViewController ที่ทำแค่ display ไม่ยุ่งกับ networking ถือว่า highly cohesive
Coupling เหมือนการที่ View ต้อง import Model โดยตรง — ถ้า tightly coupled แก้ Model ทีนึง View พัง

3.5 Drawing a Structure Chart (3 Steps)

1. Review DFDs
2. Identify program modules and relationships
3. Add couples, loops, and conditions

• After drawing: ensure consistency with all previous documentation

4. Object-Oriented Development (O-O)

4.1 Characteristics

• Individual object instances belong to classes with similar characteristics
• Relationships described using class diagrams
  • Include class attributes and methods
• Object-relationship diagrams provide an overview of object interaction

Example: Fitness Center O-O diagram

• EMPLOYEE (superclass) → MANAGER, OFFICE STAFF, INSTRUCTOR (subclasses)
• INSTRUCTOR teaches FITNESS-CLASS
• STUDENT takes FITNESS-CLASS
• REGISTRATION RECORD adds STUDENT, generates roster for FITNESS-CLASS

4.2 Implementation

• Objective: translate object methods into program code modules
• Determine what event or message will trigger each module
• O-O Cohesion & Coupling:
  • Classes should be as loosely coupled as possible
  • An object's methods should be loosely coupled and highly cohesive

5. Agile Development

• Highly iterative process
• Development team is in constant communication with the primary user (customer)
• Based on quick, nimble development that easily adapts to change
• Focuses on: small teams, intense communication, rapid development iterations

5.1 Extreme Programming (XP)

• Uses pair programming:
  • Two programmers work on the same task on the same computer
  • One programs while the other watches (and catches errors)
• Test-Driven Development (TDD):
  • Focuses on end results from the beginning
  • Prevents programmers from straying from goals
• User stories: short, simple requirements definitions written by the customer

Pair programming เหมือน navigator + driver ใน rally — คนขับ code คนนั่งข้างๆ คอย review real-time

5.2 Iterations and Releases

• Teams develop release plans
• User stories are implemented in a series of iteration cycles
  • An iteration planning meeting is held at the beginning of each cycle
  • Cycles continue until all user stories are implemented, tested, and accepted

6. Coding

• Definition: turning program logic into specific instructions
• Transform program logic into code statements
• Common programming languages: Visual Basic, Python, Java, HTML/XML, JavaScript, Swift
• Integrated Development Environment (IDE):
  • Makes it easier to program interactive software
  • Provides editing, compiling, debugging in one tool

Swift + Xcode = language + IDE — เหมือนกัน แค่ IDE ต่างกันตาม language

7. Testing

7.1 Pre-Testing Steps

• Program is compiled using a CASE tool or language compiler → detects syntax errors
• Desk checking: programmer manually traces through code → spots logic errors
• Structured walkthrough / Code review: team reviews code together

7.2 Testing Levels

Unit Testing

• Testing of an individual program or module
• Aims to identify and eliminate:
  • Execution errors: program crashes or does not run
  • Logic errors: program runs but produces wrong output
• Test data should contain both accurate AND erroneous data

Unit Testing เหมือน XCTest ใน Xcode — ทดสอบแต่ละ function แยกกัน

Integration Testing

• Testing two or more programs that depend on each other
• Ensures programs work together properly

System Testing

• Final test of the entire system
• Includes acceptance tests: key to user and management approval

8. Documentation

• Describes an information system and helps users, managers, and IT staff interact with it

User documentation เหมือน README.md หรือ App Store "What's New" — เขียนให้คนไม่รู้ technical เข้าใจได้

9. Installation

9.1 Presenting Test Results to Management

After system testing is complete, present:

• Description of test results
• Status of all required documentation
• Summary of input from users who participated
• Detailed time schedules, cost estimates, and staffing requirements

9.2 Installation Tasks

1. Prepare separate operational and test environments
2. Perform system changeover
3. Perform data conversion
4. Carry out post-implementation tasks

9.3 Operational vs. Test Environments

• A separate test environment is necessary to maintain security, integrity, and protect the operational environment
• Changes move from test → operational only when authorized

เหมือน staging server vs production server ใน DevOps — ห้าม push to production โดยไม่ผ่าน staging

9.4 System Changeover Methods

Definition: putting the new information system online and retiring the old system

Direct Cutover

• Switch from old to new immediately when new system becomes operational
• Least expensive changeover method
• IT only maintains one system at a time
• Risk: HIGH — no fallback if new system fails

Parallel Operation

• Both old and new systems operate fully for a specified period
• Advantage: lower risk — old system acts as backup
• Disadvantage: not practical if old and new systems are incompatible
• Cost: HIGH

Pilot Operation

• Implements the complete new system at a selected location (pilot site)
• Pilot site uses the new system first → reduces risk of widespread failure
• Less expensive than parallel operation
• Risk: MEDIUM

Phased Operation

• Implements the new system in stages/modules
• Combines direct cutover and parallel operation
• Only part of the system is given to all users at a time
• Risk of errors limited to the implemented module only
• Less expensive than full parallel operation
• Risk: MEDIUM

Risk vs. Cost Summary

9.5 Data Conversion

• Definition: process in which existing data is loaded onto a new system
• Strategies:
  • Automate the conversion process if possible
  • Old systems may export data in ASCII or ODBC (Open Database Connectivity)
  • If no standard format → develop a custom extraction program
• Security & Controls during conversion:
  • Maintain strict input controls
  • Ensure system control measures protect data from unauthorized access
  • Ensure error-free data is fed into the new system

9.6 Training

Training Plan

• Identify who should receive training and what training is required
• Observe the organization to determine how the system will support operations
• Main groups for training:
  • Users
  • Managers
  • IT Staff

Training Methods

Training Tips

• Train people in groups, with separate programs for distinct groups
• Select the most effective place to conduct training
• Provide learning by hearing, seeing, and doing
• Rely on previous trainees to help new ones
• Effective training is interactive, self-paced, and multimedia-based

Online Training

• Sophisticated training systems offer interactive sessions
• Include a reference section in training materials
• Conduct a full-scale test or simulation after training is complete

9.7 Post-Implementation Tasks

• Prepare a post-implementation evaluation: assesses overall quality of the new system
• Deliver a final report to management: marks the end of systems development work
  • Includes final system documentation
  • Describes any future system enhancements already identified
  • Details project costs

Summary