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System Design: Fulfillment Truck Routing and Inventory
Scenario
Design a software system for a large e-commerce fulfillment center to manage truck routes and the movement of containers and inventory both within and across facilities.
The system must support:
- Inbound trucks: Delivering pallets and containers to a fulfillment center.
- Outbound trucks: Picking up containers for delivery to other facilities or last-mile hubs.
- Container movement: Containers (e.g., totes, pallets) holding inventory items move between dock doors, staging areas, and storage locations.
Functional Requirements
- Shipment Management: Create and manage inbound and outbound loads, including lists of containers and planned arrival/departure windows.
- Dock Door Assignment: Assign trucks to specific dock doors and time slots, with the ability to detect and resolve conflicts.
- Route Planning: Given a set of stops (facilities/docks) and time windows, generate a feasible route sequence. The system must also support re-planning when conditions change (e.g., delays, cancellations).
- Container Tracking: Provide end-to-end tracking of container state, including its current location (facility + zone), status (e.g., created, staged, loaded, in-transit, received), and a summary of its contents.
- Inventory Correctness: Prevent double-allocation of containers or inventory items. Implement mechanisms to reconcile discrepancies when scans disagree or events arrive late/out of order.
- APIs/UI: Offer interfaces for dispatchers to view routes, dock door schedules, and container statuses, and for operators to scan containers.
Non-Functional Requirements
- High Availability: For critical operational workflows such as dock door assignment and scan updates.
- Low Latency: Near real-time updates for scan events.
- Auditability: Maintain a full history of all container movements and changes.
- Scalability: Support multiple warehouses/facilities.
- Security: Implement permissions and access control.
Constraints and Assumptions
- The system will handle many scan events per minute.
- It must operate across multiple facilities.
- Network partitions are expected to occur.
- Scan devices may buffer events during connectivity issues.
Deliverables
Your design should cover:
- High-level architecture (services, data stores, messaging components).
- Core data model (key entities and their relationships).
- Key APIs and events.
- Consistency strategy (e.g., idempotency, event ordering, deduplication).
- Routing and optimization approach (e.g., exact vs. heuristic, what metrics are optimized).
- Observability and failure handling mechanisms.
AI interview prep
Core dilemma
Orchestrating complex, real-time physical logistics (trucks, containers, dock doors) with high-volume event processing, distributed inventory state management, and dynamic routing optimization, all while ensuring data consistency and operational resilience.
Mid-level signals3
Senior signals5
Red flags5
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
System Design: Fulfillment Truck Routing and Inventory
Scenario
Design a software system for a large e-commerce fulfillment center to manage truck routes and the movement of containers and inventory both within and across facilities.
The system must support:
- Inbound trucks: Delivering pallets and containers to a fulfillment center.
- Outbound trucks: Picking up containers for delivery to other facilities or last-mile hubs.
- Container movement: Containers (e.g., totes, pallets) holding inventory items move between dock doors, staging areas, and storage locations.
Functional Requirements
- Shipment Management: Create and manage inbound and outbound loads, including lists of containers and planned arrival/departure windows.
- Dock Door Assignment: Assign trucks to specific dock doors and time slots, with the ability to detect and resolve conflicts.
- Route Planning: Given a set of stops (facilities/docks) and time windows, generate a feasible route sequence. The system must also support re-planning when conditions change (e.g., delays, cancellations).
- Container Tracking: Provide end-to-end tracking of container state, including its current location (facility + zone), status (e.g., created, staged, loaded, in-transit, received), and a summary of its contents.
- Inventory Correctness: Prevent double-allocation of containers or inventory items. Implement mechanisms to reconcile discrepancies when scans disagree or events arrive late/out of order.
- APIs/UI: Offer interfaces for dispatchers to view routes, dock door schedules, and container statuses, and for operators to scan containers.
Non-Functional Requirements
- High Availability: For critical operational workflows such as dock door assignment and scan updates.
- Low Latency: Near real-time updates for scan events.
- Auditability: Maintain a full history of all container movements and changes.
- Scalability: Support multiple warehouses/facilities.
- Security: Implement permissions and access control.
Constraints and Assumptions
- The system will handle many scan events per minute.
- It must operate across multiple facilities.
- Network partitions are expected to occur.
- Scan devices may buffer events during connectivity issues.
Deliverables
Your design should cover:
- High-level architecture (services, data stores, messaging components).
- Core data model (key entities and their relationships).
- Key APIs and events.
- Consistency strategy (e.g., idempotency, event ordering, deduplication).
- Routing and optimization approach (e.g., exact vs. heuristic, what metrics are optimized).
- Observability and failure handling mechanisms.