Problem Statement
Design a chat messaging system with a unique "read-once" delivery mechanism. A sender can dispatch a single message to multiple specified recipients simultaneously. However, unlike a traditional group chat, each recipient receives an independent copy of the message.
Core Requirements
- Multi-Recipient Send: A sender must be able to send the same message to multiple distinct recipients in a single operation.
- Single View Enforcement: Each recipient must be able to view their copy of the message only one time.
- Ephemeral Messages: Immediately after a recipient views their message, that specific copy must be permanently deleted or rendered inaccessible to them.
- Recipient Isolation: The act of one recipient reading their message must not, under any circumstances, affect the availability or state of any other recipient's copy of the same message.
- Robust Delivery: The system must reliably support message delivery to online recipients, queue messages for offline recipients, handle retries, and scale to accommodate large-scale traffic volumes.
Design Considerations
Please describe your approach for the following aspects:
- APIs: Define the necessary interfaces for sending and receiving messages.
- Data Model: Outline the schema for storing messages, recipients, and read states.
- High-Level Architecture: Present a block diagram and explain the major components and their interactions.
- Message Fan-out Strategy: Detail how a single sender's message is distributed to multiple individual recipient queues or storage locations.
- Read-Once Enforcement: Explain the mechanisms to guarantee that a message is viewed only once per recipient.
- Deletion and Retention Behavior: Describe how messages are deleted post-read and any retention policies for unread messages.
- Scaling, Load Balancing, and Partitioning: Discuss strategies for horizontal scaling, distributing load, and partitioning data to handle high traffic.
- Failure Handling and Consistency Tradeoffs: Address how the system handles component failures and the consistency guarantees provided, especially concerning the read-once property.
AI interview prep
Core dilemma
Ensuring strict 'exactly once read' semantics for each individual recipient's copy of a message, while simultaneously handling large-scale fan-out, asynchronous delivery, and atomic deletion across a distributed system.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Problem Statement
Design a chat messaging system with a unique "read-once" delivery mechanism. A sender can dispatch a single message to multiple specified recipients simultaneously. However, unlike a traditional group chat, each recipient receives an independent copy of the message.
Core Requirements
- Multi-Recipient Send: A sender must be able to send the same message to multiple distinct recipients in a single operation.
- Single View Enforcement: Each recipient must be able to view their copy of the message only one time.
- Ephemeral Messages: Immediately after a recipient views their message, that specific copy must be permanently deleted or rendered inaccessible to them.
- Recipient Isolation: The act of one recipient reading their message must not, under any circumstances, affect the availability or state of any other recipient's copy of the same message.
- Robust Delivery: The system must reliably support message delivery to online recipients, queue messages for offline recipients, handle retries, and scale to accommodate large-scale traffic volumes.
Design Considerations
Please describe your approach for the following aspects:
- APIs: Define the necessary interfaces for sending and receiving messages.
- Data Model: Outline the schema for storing messages, recipients, and read states.
- High-Level Architecture: Present a block diagram and explain the major components and their interactions.
- Message Fan-out Strategy: Detail how a single sender's message is distributed to multiple individual recipient queues or storage locations.
- Read-Once Enforcement: Explain the mechanisms to guarantee that a message is viewed only once per recipient.
- Deletion and Retention Behavior: Describe how messages are deleted post-read and any retention policies for unread messages.
- Scaling, Load Balancing, and Partitioning: Discuss strategies for horizontal scaling, distributing load, and partitioning data to handle high traffic.
- Failure Handling and Consistency Tradeoffs: Address how the system handles component failures and the consistency guarantees provided, especially concerning the read-once property.