SYSTEM DESIGN FINALS

Design Phase

The stage in SDLC that transforms business needs (what) into system solutions (how).

System Specifications

The final compiled document of all design outputs, used for approval before implementation

Custom Development (In-House)

Building the system internally to fully match requirements.

Packaged Software

Pre-built software purchased and adapted to the organization

Outsourcing

Hiring an external vendor to develop the system.

Time and Materials Contract

Pay based on time and expenses.

Fixed-Price Contract

Predefined cost for specific requirements.

Value-Added Contract

Vendor earns based on system benefits.

Alternative Matrix

A comparison table used to evaluate system options based on feasibility (technical, economic, organizational)

Architecture Design

Blueprint showing how software, hardware, and data are distributed.

System Architect

Expert who designs integrated systems that meet requirements.

Hardware

Physical devices (clients, servers, network).

Software

Programs and logic.

Data Storage

Databases and files.

Application Logic

Core system processes.

Presentation Logic

User interface display.

Data Access Logic

Data retrieval methods.

Client-Server Architecture

Tasks divided between client and server.

Server-Based Architecture

All processing handled by the server.

Mobile Application Architecture

Designed for mobile environments.

Two-Tier

Client + Server

Three-Tier

Client + App Server + Database Server

N-Tier

Multiple specialized layers

Virtualization

Creating virtual versions of hardware resources.

Cloud Computing

Delivering IT services over the internet.

Elasticity

Ability to scale resources up or down.

Cloud Deployment Models

Public, Private, Hybrid.

Operational Requirements

System environment and maintainability.

Performance Requirements

Speed, capacity, reliability.

Security Requirements

Protection, access control, encryption.

Cultural/Political Requirements

Localization, legal compliance.

Hardware and Software Specification

Document listing required system technologies.

User Interface Design

Designing interaction between users and system.

Navigation Mechanism

How users move through the system.

Input Mechanism

How data is entered.

Output Mechanism

How information is displayed.

Usability

Ease of use and learning.

Layout

Organized screen structure.

Consistency

Uniform design elements.

Aesthetics

Visual appeal and readability.

Content Awareness

Users know their location in the system.

Minimize User Effort

Reduce clicks and actions.

Personas

Fictional user profiles.

Use Scenarios

Steps users take to complete tasks.

Logical DFD

Shows what the system does (no technology).

Physical DFD

Shows how the system works (includes technology).

Structure Chart

Diagram showing program hierarchy and module relationships.

Program Specification

Detailed description of a module (inputs, outputs, logic).

Pseudocode

Language-independent representation of program logic.

Event-Driven Programming

Code executes in response to events (clicks, inputs).

Data Storage

Process of storing data for retrieval and analysis.

Flat File

Simple file, no relationships.

Hierarchical Database

Tree structure.

Network Database

Complex relationships.

Relational Database

Table-based (most common).

RDBMS

Relational database system (e.g., SQL-based).

NoSQL

Non-relational database (flexible structure).

Cloud Database

Hosted online database

Integrity

Accuracy of data

Consistency

Same data across system.

Security

Protection from unauthorized access

Availability

Accessible when needed.

Efficiency

Fast performance

Logical ERD

Business-level design.

Physical ERD

Technical implementation.

Entities

Tables

Attributes

Columns

Relationships

Foreign Keys

Normalization

Remove redundancy.

Denormalization

Improve performance.

Partitioning

Split large tables.

Efficient Data Types

Use minimal storage.

Index

Data structure that speeds up data retrieval.

Database Size Formula

Size = Number of Records × Size per Record