Product Requirements Document (PRD)

Change History

Version	Date	Author	Changes
1.0	2024-12-19	Engineering Team	Initial PRD creation
1.1	2024-12-19	Engineering Team	Added WebSocket and SSE requirements
1.2	2024-12-19	Engineering Team	Added OpenAPI documentation requirements

Overview

The [dummy-responder] is a configurable mock service designed to simulate various HTTP, WebSocket, and Server-Sent Events scenarios for testing and development workflows. The service enables development teams to test their applications against predictable, controllable backend responses without requiring complex setup or external dependencies.

Problem Statement

Development and QA teams frequently need to test applications against various backend scenarios including:

• Different HTTP response codes and content types
• Network delays and timeouts
• Intermittent failures and error conditions
• Real-time communication patterns (WebSocket, SSE)
• Load testing scenarios

Existing solutions are often:

• Overly complex for simple testing scenarios
• Require extensive configuration or external dependencies
• Lack real-time protocol support
• Don't provide adequate documentation or examples

Success Metrics

Metric	Target	Measurement
Adoption Rate	80% of development teams	Usage analytics, internal surveys
Time to First Test	< 5 minutes	User onboarding tracking
Documentation Quality	> 4.5/5 rating	Developer feedback surveys
Reliability	99.9% uptime	Service monitoring
Performance	< 10ms response time	Performance monitoring

Messaging

Primary Value Proposition: "Zero-configuration mock service that supports modern web protocols and provides instant testing capabilities for development teams."

Key Messages:

• For Development Teams: "Start testing immediately with no setup required"
• For QA Engineers: "Simulate any network condition or failure scenario"
• For DevOps Teams: "Container-ready with Kubernetes manifests included"

Timeline/Release Planning

Phase 1: Core HTTP Functionality ✅

• Duration: Completed
• Features: Basic HTTP responses, configurable status codes, delays, content types

Phase 2: Real-time Protocols ✅

• Duration: Completed
• Features: WebSocket support, Server-Sent Events, interactive examples

Phase 3: Documentation & Tooling ✅

• Duration: Completed
• Features: OpenAPI/Swagger integration, comprehensive documentation

Phase 4: Enhanced Features (Future)

• Duration: 2-4 weeks
• Features: Metrics endpoint, configuration files, rate limiting

Personas

Primary Persona: Backend Developer (Sarah)

• Role: Senior Backend Developer
• Goals: Quickly test API integrations, simulate various response scenarios
• Pain Points: Time-consuming mock service setup, limited configuration options
• Tech Stack: Go, Docker, Kubernetes, REST APIs

Secondary Persona: QA Engineer (Marcus)

• Role: Quality Assurance Engineer
• Goals: Test edge cases, simulate failure conditions, validate error handling
• Pain Points: Inconsistent test environments, difficulty reproducing issues
• Tech Stack: Postman, curl, automated testing frameworks

Tertiary Persona: DevOps Engineer (Lisa)

• Role: DevOps/Infrastructure Engineer
• Goals: Reliable testing infrastructure, easy deployment, monitoring
• Pain Points: Complex service dependencies, difficult troubleshooting
• Tech Stack: Kubernetes, Docker, CI/CD pipelines, monitoring tools

User Scenarios

Scenario 1: API Integration Testing (Sarah - Backend Developer)

Sarah is developing a new microservice that needs to integrate with a third-party payment API. She wants to test her error handling logic without making actual API calls or setting up complex mock servers.

Journey:

1. Sarah runs docker run -p 8080:8080 dummy-responder
2. She configures her application to point to http://localhost:8080
3. She tests various scenarios: curl "http://localhost:8080/?status=422&delay=3s"
4. She validates her application handles timeouts and error codes correctly
5. She integrates these tests into her CI/CD pipeline

Scenario 2: Frontend Real-time Features (Marcus - QA Engineer)

Marcus needs to test a new dashboard that displays real-time data via WebSocket connections and handles various connection states.

Journey:

1. Marcus starts the [dummy-responder]: make run
2. He opens the WebSocket test page at http://localhost:8080/test-ws.html
3. He simulates connection drops and reconnection scenarios
4. He tests different message types and validates UI responses
5. He creates automated tests using the provided examples

Scenario 3: Load Testing Environment (Lisa - DevOps Engineer)

Lisa needs to set up a consistent testing environment for load testing the company's new API gateway with predictable backend responses.

Journey:

1. Lisa deploys dummy-responder to Kubernetes: kubectl apply -f k8s-example.yaml
2. She configures multiple instances with different response patterns
3. She runs load tests with k6 using the provided scripts
4. She monitors performance and adjusts configuration as needed
5. She documents the setup for other teams to use

Service Interactions

Primary Service	Secondary Service	Interaction Type	Trigger
dummy-responder	client-application	HTTP Response	HTTP request received
dummy-responder	websocket-client	WebSocket Message	WebSocket connection established
dummy-responder	sse-client	Server-Sent Event	SSE connection established
dummy-responder	logging-system	Log Entry	Any request processed
dummy-responder	monitoring-system	Metrics	Health check request

Requirement Specifications

Requirement ID	Actor	Action	System Response	Acceptance Criteria
HTTP-0001	Backend Developer	sends GET request to "/"	dummy-responder returns HTTP 200 with "Hello, World!"	Given service is running When GET / requested Then returns 200 OK And body contains "Hello, World!"
HTTP-0002	QA Engineer	sends request with "?status=404"	dummy-responder returns HTTP 404	Given service is running When request includes status=404 Then returns 404 Not Found
HTTP-0003	Developer	sends request with "?delay=2s"	dummy-responder waits 2 seconds then responds	Given service is running When request includes delay=2s Then response takes ~2 seconds And returns 200 OK
HTTP-0004	QA Engineer	sends request with "?content-type=json"	dummy-responder returns JSON response	Given service is running When request includes content-type=json Then response has Content-Type: application/json And body contains valid JSON
HTTP-0005	Developer	sends request with "?failure-rate=50"	dummy-responder returns error ~50% of time	Given service is running When multiple requests with failure-rate=50 Then ~50% return error status
WS-0001	Frontend Developer	establishes WebSocket connection to "/ws"	dummy-responder accepts WebSocket upgrade	Given service is running When WebSocket connection to /ws Then connection established And receives welcome message
WS-0002	Developer	sends WebSocket message "hello"	dummy-responder echoes "Echo: hello"	Given WebSocket connected When client sends "hello" Then receives "Echo: hello"
SSE-0001	Frontend Developer	connects to "/events" for SSE	dummy-responder starts event stream	Given service is running When GET /events with Accept: text/event-stream Then SSE connection established And periodic events received
DOC-0001	Any User	accesses "/swagger/"	dummy-responder serves Swagger UI	Given service is running When GET /swagger/ Then Swagger UI displayed And API endpoints documented
HEALTH-0001	DevOps Engineer	sends GET to "/health"	dummy-responder returns health status	Given service is running When GET /health Then returns 200 OK And JSON health status

User Stories/Features/Requirements

Core HTTP Features

• HTTP-001: As a developer, I want to receive configurable HTTP status codes so that I can test my error handling logic
• HTTP-002: As a QA engineer, I want to simulate network delays so that I can test timeout handling
• HTTP-003: As a developer, I want different content types (JSON, XML, HTML) so that I can test content parsing
• HTTP-004: As a tester, I want to simulate intermittent failures so that I can test retry logic

Real-time Protocol Features

• WS-001: As a frontend developer, I want WebSocket echo functionality so that I can test bidirectional communication
• WS-002: As a developer, I want WebSocket broadcast capabilities so that I can test multi-client scenarios
• SSE-001: As a frontend developer, I want Server-Sent Events so that I can test real-time data streaming

Documentation & Usability

• DOC-001: As any user, I want interactive API documentation so that I can understand available endpoints
• DOC-002: As a developer, I want comprehensive examples so that I can quickly integrate the service
• DOC-003: As a new user, I want clear getting-started guides so that I can be productive immediately

Deployment & Operations

• DEPLOY-001: As a DevOps engineer, I want Docker containers so that I can deploy consistently across environments
• DEPLOY-002: As a platform engineer, I want Kubernetes manifests so that I can deploy to clusters
• DEPLOY-003: As an operator, I want health check endpoints so that I can monitor service status

Performance & Reliability

• PERF-001: As a load tester, I want high throughput (>1000 req/s) so that I can stress test my applications
• PERF-002: As a developer, I want low latency (<10ms) so that tests run quickly
• REL-001: As a user, I want graceful shutdown so that active connections are handled properly

Gherkin Scenarios (Ready-to-Use)

HTTP Response Configuration

Feature: Configurable HTTP Responses

  Scenario: Developer configures custom status code
    Given the [dummy-responder] service is running on port 8080
    And the service is healthy
    When a Developer sends GET request to "/?status=201"
    Then the response status code is 201
    And the response is received within 100ms

  Scenario: QA Engineer simulates network delay
    Given the [dummy-responder] service is running
    When a QA Engineer sends GET request to "/?delay=2s&status=200"
    Then the response takes approximately 2 seconds
    And the response status code is 200
    And the response body contains "Hello, World!"

  Scenario: Developer tests JSON responses  
    Given the [dummy-responder] service is running
    When a Developer sends GET request to "/?content-type=json"
    Then the response Content-Type header is "application/json"
    And the response body contains valid JSON
    And the JSON contains a timestamp field

WebSocket Communication

Feature: WebSocket Communication

  Scenario: Frontend Developer establishes WebSocket connection
    Given the [dummy-responder] service is running
    When a Frontend Developer connects to WebSocket endpoint "/ws"
    Then the WebSocket connection is established successfully
    And the client receives a welcome message
    And the connection remains open for bidirectional communication

  Scenario: Developer tests WebSocket message echo
    Given a WebSocket connection is established to "/ws"  
    When the Developer sends message "test message"
    Then the server responds with "Echo: test message"
    And the response is received within 100ms

Server-Sent Events

Feature: Server-Sent Events

  Scenario: Frontend Developer subscribes to event stream
    Given the [dummy-responder] service is running
    When a Frontend Developer sends GET to "/events" with Accept header "text/event-stream"
    Then an SSE connection is established
    And periodic events are received every 5 seconds  
    And each event contains timestamp and message data
    And the connection supports automatic reconnection

Documentation and API Discovery

Feature: API Documentation

  Scenario: User accesses interactive API documentation
    Given the [dummy-responder] service is running  
    When any User navigates to "/swagger/"
    Then the Swagger UI interface is displayed
    And all HTTP endpoints are documented with examples
    And the user can test endpoints directly from the interface
    And response schemas are clearly defined

Designs

System Architecture

API Response Flow

Open Issues

Technical Considerations

1. Rate Limiting: Should we implement built-in rate limiting to prevent DoS scenarios?
2. Metrics Endpoint: Do we need Prometheus metrics for production monitoring?
3. Configuration Files: Should we support YAML/JSON configuration in addition to parameters?
4. Authentication: Is basic auth needed for production deployments?

Product Decisions

1. Versioning Strategy: How should we handle API versioning for future enhancements?
2. Multi-instance Support: Should we support clustering for high-availability scenarios?
3. Plugin Architecture: Is extensibility through plugins a future requirement?

Operational Questions

1. Log Aggregation: What's the preferred logging format for enterprise environments?
2. Security Scanning: What security compliance requirements must we meet?
3. Performance Benchmarking: What are the realistic performance targets for production use?

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Document Status: Living document, updated with each release Next Review: Quarterly review with development and product teams Feedback: Submit issues and feature requests via GitHub issues