# ChatterBox: Real-time Team Messaging Platform ## Problem Statement Design a scalable, real-time team messaging platform similar to Slack, called ChatterBox. Users should be able to create teams, join channels within those teams, send direct messages to other users, share files, and search through message history. The system needs to handle a large number of concurrent users and messages with low latency. ## Core Requirements (Functional) * **User Management:** User registration, login, profile management. * **Team Creation & Management:** Users can create teams and add/remove members. * **Channel Creation & Management:** Within a team, users can create public and private channels. * **Messaging:** * Sending and receiving text messages in channels and direct messages. * Real-time message delivery. * Message editing and deletion (with appropriate permissions). * Message threading (replies to messages). * **File Sharing:** Users can upload and download files within channels and direct messages. * **Search:** Users can search for messages based on keywords, users, and channels. * **Presence:** Indicate user online/offline status. * **Notifications:** Desktop and mobile push notifications for new messages and mentions. ## Non-Functional Requirements * **Scale:** The system should be able to handle a large number of concurrent users and messages. * **Latency:** Message delivery should be near real-time (target: < 200ms for 95th percentile). * **Availability:** The system should be highly available (target: 99.9% uptime). * **Reliability:** Messages should be reliably delivered, even in the face of network failures. * **Security:** Messages should be encrypted in transit and at rest. Access control should be enforced. ## Key Features to Design 1. **Message Routing & Delivery:** How will messages be routed from sender to recipients in real-time? 2. **Data Storage:** What database(s) will be used to store messages, users, teams, and channels? Consider the trade-offs between relational and NoSQL databases. 3. **Real-time Communication:** How will real-time communication be implemented (e.g., WebSockets, Server-Sent Events)? 4. **Search Indexing:** How will messages be indexed for efficient search? 5. **File Storage:** How will files be stored and served? 6. **Scalability & Fault Tolerance:** How will the system be scaled to handle increasing load and ensure high availability? ## Expected Traffic/Scale Numbers * **Daily Active Users (DAU):** 10 million * **Monthly Active Users (MAU):** 50 million * **Average Messages per User per Day:** 50 * **Peak Concurrent Users:** 2 million * **Average Message Size:** 1KB * **Average File Size:** 5MB * **Read/Write Ratio:** 8:2 (Reads are more frequent than writes) * **Retention Policy:** Store message history for at least 1 year. * **Number of Teams:** 500,000 * **Average Channels per Team:** 20

ScalabilityReal-timeDatabaseWebSocketsCachingMessage QueueSearchPrivateBYOP

35-45 min

Start Design

HLDHard