SYSTEM DESIGN MIDTERM

Process Modeling

Graphical representation of processes that capture, manipulate, store, and distribute data within a system and its environment.

Data Flow Diagram (DFD)

A diagram used to show how data flows through an information system and how it is processed

Process Model

Another term for DFD because it focuses on the movement of data between processes.

Data Flow

Represents data in motion (moving from one part of the system to another).
👉 Example: customer order, report, database query

Data Store

A place where data is stored.
👉 Example: database, file folder, notebook

Process

Actions performed on data to transform, store, or distribute it.

Source/Sink (External Entity)

The origin or destination of data outside the system.
👉 Example: customer, bank, other system

Context Diagram

The highest-level DFD that shows the entire system as a single process (Process 0).

Level-0 Diagram (Top-Level DFD)

Breaks down the system into major processes.

Level-1 / Level-2 Diagram

Shows further detailed decomposition of processes.

Primitive DFD

The lowest level where processes can no longer be broken down.

Functional Decomposition

The process of breaking a system into smaller and more detailed processes step-by-step.

External Entity

Same as source/sink; entities outside the system boundary.

System Boundary

The limit that separates the system from external entities.

Input ≠ Output Rule

Inputs to a process must be different from outputs.

Unique Naming Rule

All elements in a DFD must have unique names.

Deliverables of Process Modeling

Context DFD

Decomposed DFDs

Component Descriptions

Context DFD

Overview of the system

Decomposed DFDs

Detailed diagrams of processes

Component Descriptions

Explanation of each DFD element