Requirements gathering (functional and non-functional) in HLD - Architecture Diagram

System Overview - Requirements gathering (functional and non-functional)

This system helps teams collect and organize requirements for software projects. It supports capturing both functional needs (what the system should do) and non-functional needs (how the system should perform or behave).

Key requirements include easy input of requirements, categorization, and clear visibility for stakeholders.

Architecture Diagram

User
  |
  v
Web Interface
  |
  v
API Server
  |
  v
Requirements Database
  |
  v
Notification Service
  |
  v
Stakeholder Dashboard

Components

User

actor

Person who inputs or reviews requirements

Web Interface

frontend

Allows users to enter and view requirements

API Server

service

Processes requests and manages business logic

Requirements Database

database

Stores all functional and non-functional requirements

Notification Service

service

Sends alerts to stakeholders about updates

Stakeholder Dashboard

frontend

Displays organized requirements and status to stakeholders

Request Flow - 6 Hops

User → Web Interface

Web Interface → API Server

API Server → Requirements Database

API Server → Notification Service

Notification Service → Stakeholder Dashboard

Stakeholder Dashboard → User

Failure Scenario

Component Fails:Requirements Database

Impact:New requirements cannot be saved; existing data is inaccessible

Mitigation:Use database replication and backups; cache recent requirements for read-only access

Architecture Quiz - 3 Questions

Which component stores the functional and non-functional requirements?

A Requirements Database

B Notification Service

C API Server

D Stakeholder Dashboard

Design Principle

This architecture separates concerns by using dedicated components for user interaction, processing, storage, and notifications. It ensures scalability and clear responsibility boundaries, which helps manage both functional and non-functional requirements effectively.

Practice

1. Which of the following best describes a functional requirement in system design?

easy

A. A usability guideline for user interface design

B. A quality that defines how fast the system should respond

C. A security measure to protect user data

D. A feature that defines what the system should do

Solution

1. Step 1: Understand functional requirements

   Functional requirements specify the actions or features the system must perform, such as user login or data processing.

2. Step 2: Differentiate from non-functional requirements

   Non-functional requirements describe qualities like speed, security, or usability, not specific features.

3. Final Answer:

   A feature that defines what the system should do -> Option D

4. Quick Check:

   Functional = What system does [OK]

Hint: Functional = what system does; Non-functional = how well [OK]

Common Mistakes:

• Confusing functional with non-functional requirements
• Thinking security is a functional requirement
• Mixing usability with system features

2. Which of the following is a correct example of a non-functional requirement?

easy

A. The system shall respond to user requests within 2 seconds

B. The system shall provide a search feature

C. The system shall store user profiles

D. The system shall allow users to reset their password

Solution

1. Step 1: Identify non-functional requirements

   Non-functional requirements describe system qualities like performance, reliability, or security.

2. Step 2: Match options to definitions

   The system shall respond to user requests within 2 seconds specifies response time, a performance metric, which is non-functional. Others describe features (functional).

3. Final Answer:

   The system shall respond to user requests within 2 seconds -> Option A

4. Quick Check:

   Non-functional = system qualities [OK]

Hint: Look for qualities like speed or security for non-functional [OK]

Common Mistakes:

• Choosing features as non-functional requirements
• Ignoring time or performance constraints
• Confusing functional and non-functional examples

3. Given these requirements:

• The system must allow users to upload files.
• Uploads must complete within 5 seconds.
• The system must support 1000 concurrent uploads.

Which of these is a functional requirement?

medium

A. Uploads must complete within 5 seconds

B. The system must support 1000 concurrent uploads

C. The system must allow users to upload files

D. The system must ensure uploaded files are available 99.9% of the time

Solution

1. Step 1: Identify functional requirements

   Functional requirements describe what the system does, such as allowing file uploads.

2. Step 2: Analyze each option

   A is performance (non-functional). B is capacity/scalability (non-functional). D is availability (non-functional).

3. Final Answer:

   The system must allow users to upload files -> Option C

4. Quick Check:

   Functional = system features [OK]

Hint: Features = functional; qualities like speed = non-functional [OK]

Common Mistakes:

• Selecting performance, capacity, or availability as functional
• Confusing capacity constraints as functional
• Ignoring direct feature statements

4. A system requirement states: "The system shall handle 1000 requests per second." Which type of requirement is this and what is wrong if it is listed as functional?

medium

A. Functional; it describes a feature, so it's correct

B. Non-functional; it describes performance, so listing as functional is incorrect

C. Functional; it describes user behavior, so it's correct

D. Non-functional; it describes security, so listing as functional is incorrect

Solution

1. Step 1: Identify requirement type

   Handling 1000 requests per second is about performance, a non-functional quality.

2. Step 2: Explain why listing as functional is wrong

   Functional requirements describe features, not performance metrics. Mislabeling causes confusion in design and testing.

3. Final Answer:

   Non-functional; it describes performance, so listing as functional is incorrect -> Option B

4. Quick Check:

   Performance = non-functional [OK]

Hint: Performance metrics are non-functional, not features [OK]

Common Mistakes:

• Calling performance a functional requirement
• Confusing user behavior with system qualities
• Ignoring the impact of mislabeling requirements

5. You are gathering requirements for a new messaging app. Which combination below correctly pairs functional and non-functional requirements?

hard

A. Users can send messages; messages must be delivered within 1 second

B. Messages must be encrypted; users can create profiles

C. The app must support dark mode; users can block contacts

D. The app must be available 24/7; Messages must be delivered with 99.99% reliability

Solution

1. Step 1: Identify functional requirements in options

   Functional requirements describe features like sending messages or creating profiles.

2. Step 2: Identify non-functional requirements in options

   Non-functional requirements describe qualities like speed, availability, or security.

3. Step 3: Analyze each option pair

   Users can send messages; messages must be delivered within 1 second pairs sending messages (functional) with delivery speed (non-functional). Others mix two functional or two non-functional requirements incorrectly.

4. Final Answer:

   Users can send messages; messages must be delivered within 1 second -> Option A

5. Quick Check:

   Functional + Non-functional = Users can send messages; messages must be delivered within 1 second [OK]

Hint: Functional = features; Non-functional = qualities like speed or availability [OK]

Common Mistakes:

• Mixing two functional or two non-functional requirements
• Confusing UI features with system qualities
• Ignoring delivery time as non-functional