Messenger

Messenger is a relational database design for modern messaging applications. It provides a practical schema to build both one-to-one and group chat systems with support for common messaging workflows.

If you use this project in production or for learning, feel free to share your implementation.

What This Repository Includes

• messenger.sql: SQL schema for a messaging platform.
• Messenger.mwb: MySQL Workbench model file for visual schema design.
• Messenger.png: ER-style diagram preview of the schema.

Documentation

• ARCHITECTURE.md: Table domains, relationships, and design notes.
• AGENTS.md: Cross-agent development rules for this repository.
• CLAUDE.md: Claude-specific implementation guidance.
• .github/copilot-instructions.md: Copilot-specific coding guidance.
• docs/AGENTIC_DEVELOPMENT.md: AI-assisted development workflow.
• docs/NODE_EXPRESS_TYPESCRIPT_POSTGRES_SOCKET.md: Node.js + Express + TypeScript + PostgreSQL + Socket.IO implementation guide.
• docs/GO_POSTGRES_SOCKET.md: Go + PostgreSQL + WebSocket implementation guide.
• CONTRIBUTING.md: Contribution and pull request expectations.

Prompt Pack

• .github/prompts/node-express-typescript-postgres-socket.prompt.md: Generate a full Node.js backend scaffold.
• .github/prompts/go-postgres-socket.prompt.md: Generate a full Go backend scaffold.
• .github/prompts/dual-backend-roadmap.prompt.md: Generate a phased delivery roadmap for both stacks.

Core Capabilities

• One-to-one conversation support.
• Group chat support.
• Message persistence and relational integrity.
• Attachment/gallery table support for media messages.
• Device access modeling improvements from previous versions.

Platform Flow

flowchart LR
	A[User Registration] --> B[User Verification]
	B --> C[Device Registration]
	C --> D[Access Token Issued]
	D --> E[Contact Sync]
	E --> F[Conversation Creation]
	F --> G[Participant Join]
	G --> H[Message Send]
	H --> I[Attachment Save]
	H --> J[Activity Log]
	H --> K[Moderation Checks]
	K --> L[Report or Block]

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Quick Start

1. Import messenger.sql into your MySQL-compatible database.
2. Open Messenger.mwb in MySQL Workbench if you want to inspect or extend the model visually.
3. Connect your API/service layer to this schema and implement your messaging logic.

Suggested Use Cases

• Mobile chat backend foundations.
• SaaS communication modules.
• Prototyping chat APIs.
• Learning relational modeling for messaging apps.
• Dating app real-time chat and trust/safety messaging.

Use Case Library

Core Messaging Use Cases

• One-to-one direct messaging.
• Group conversation messaging.
• Message history retrieval by conversation.
• Multi-media messaging using attachments.
• Soft delete behavior for user-visible message cleanup.
• Conversation hide/delete per user.

Identity and Access Use Cases

• Phone and email based account registration.
• User verification with temporary verification codes.
• Multi-device registration per user.
• Token issuance and token revocation modeling.
• Device-level session tracking.

Contact and Network Use Cases

• Contact import and synchronization.
• User-to-contact linking for personalized contact books.
• Contact-based conversation bootstrapping.

Moderation and Safety Use Cases

• Blocking a user in a conversation context.
• Reporting users or conversation participants.
• Tracking moderation status from pending to resolved.

Product and Engagement Use Cases

• Activity feed generation for app events.
• Auditing major messaging actions.
• Push-ready architecture through device token storage.

SaaS Collaboration Use Cases

• Team workspace channels for project or department communication.
• Tenant-style customer support chat between users and account teams.
• Internal incident and operations communication rooms.
• Secure conversation audit trails for compliance review.
• Multi-device employee messaging with controlled token access.

Dating App Integration Use Cases

• Match-to-chat activation after a successful match event.
• One-to-one private messaging between matched users.
• Media sharing inside match conversations.
• User report and block flows for trust and safety.
• Soft-delete and hide-conversation behavior for privacy expectations.
• Activity logging for abuse detection and moderation analytics.

Engineering and Learning Use Cases

• API-first chat backend prototyping.
• Database design interviews and exercises.
• Proof-of-concept schema for startup MVPs.
• Foundation schema for a larger microservice split.

Use Case to Table Mapping

graph TD
	U1[Account Signup] --> T1[users]
	U1 --> T2[user_verification]
	U2[Contact Sync] --> T3[contacts]
	U2 --> T4[user_contact]
	U3[Create Conversation] --> T5[conversation]
	U3 --> T6[participants]
	U4[Send Message] --> T7[messages]
	U4 --> T8[attachments]
	U5[Delete Message for User] --> T9[deleted_messages]
	U6[Hide Conversation for User] --> T10[deleted_conversations]
	U7[Block or Report User] --> T11[block_list]
	U7 --> T12[reports]
	U8[Session Access] --> T13[devices]
	U8 --> T14[access]
	U9[Track User Event] --> T15[activities]
	U10[SaaS Workspace Channel Chat] --> T5
	U10 --> T6
	U10 --> T7
	U11[Dating Match Chat] --> T5
	U11 --> T6
	U11 --> T7
	U11 --> T11
	U11 --> T12

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Dating App Integration Blueprint

flowchart LR
    M[Match Service Emits Match Event] --> C[Create Conversation]
    C --> P[Insert Two Participants]
    P --> X[Enable Socket Room]
    X --> Y[Allow Message and Attachment Events]
    Y --> Z[Trust and Safety Checks]
    Z --> R[Report or Block if Needed]

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Need Help Building an App or API?

For implementation support, contact hi@crew.lk or visit Crew. Crew is an open innovation house based in Sri Lanka.

Version History

Based on git commit history:

1.0.4 (2020-09-14)

Added a unique index on participants(conversation_id, user_id). Commit: d41bb71

1.0.3 (2020-01-11)

Added attachment table support for message galleries. Commit: 4f83420

1.0.2 (2018-02-03)

Fix for issue #4. Commit: f45a282

1.0.1 (2015-11-25)

Updated access-to-device relationship to one-to-one. Commits: ffea804, 936038e

1.0.0 (2015-05-28)

Initial release. Commit: 2c2b89f