Requirements

Let's refine our restaurant application for malls. Malls present a unique challenge: high foot traffic, variable demand surges (lunch rush, movie dismissals), and impatient customers who might wander off to another establishment if the wait is too long. The goal is to design a robust and efficient waiting queue system that minimizes customer wait times and maximizes restaurant table utilization. This system needs to handle the complexities of parties of different sizes, table configurations, and customer preferences (e.g., booth vs. table, near window). We need to optimize the assignment of customers to tables to avoid wasting seating capacity and maintain a smooth flow of customers through the restaurant. Furthermore, we need to manage customer expectations by providing accurate wait time estimates and timely updates. # Requirements ## Functional Requirements 1. **Waiting Queue Management:** * Customers can join the waiting queue with their party size and any preferences (e.g., booth, high chair). * Customers can optionally provide a contact number to receive SMS updates when their table is ready. * The system should track the customer's position in the queue and estimated wait time. * Customers can check their wait time and position in the queue via a kiosk or app. * Restaurant staff can manually add, remove, or re-prioritize customers in the queue (e.g., VIP customers). * The system should support different queue management strategies (e.g., First-In-First-Out (FIFO), priority-based on party size). * The system must handle "no-shows" (customers who don't respond when their table is ready) efficiently, after a reasonable grace period. * Support dynamic updates to the estimated wait time based on real-time factors (e.g., table turnover rate, kitchen delays). * Support pre-booking for a time slot, effectively adding the customer to the waitlist for the selected time. 2. **Table Management:** * Define table configurations (number of seats, location, type - booth, high-top, etc.). * Track table availability status (available, occupied, dirty, reserved). * Support combining multiple tables to accommodate larger parties. * The system should automatically suggest the best table(s) for a given party size, considering customer preferences and table availability. * Track the time each table has been occupied to estimate table turnover rates. 3. **Table Assignment:** * Automatically assign tables to waiting customers based on party size, customer preferences, and table availability. * Support manual table assignment by restaurant staff. * Notify customers (via SMS or in-app notification) when their table is ready. * Provide a grace period for customers to claim their table before it is offered to the next customer in the queue. 4. **Reporting and Analytics:** * Generate reports on average wait times, table turnover rates, and customer no-show rates. * Provide insights into peak demand periods to optimize staffing and table configurations. * Track customer preferences to improve table assignment strategies. ## Non-Functional Requirements 1. **Thread Safety:** The waiting queue and table management systems must be thread-safe to handle concurrent requests from multiple users and restaurant staff. Consider synchronization mechanisms (locks, concurrent data structures) to prevent race conditions and ensure data consistency. 2. **Extensibility:** The system should be designed to accommodate future features and changes, such as: * Integration with online reservation systems. * Support for different notification channels (e.g., email, push notifications). * More sophisticated queue management strategies. * Integration with kitchen display systems (KDS) to track food preparation times. * Support for loyalty programs and personalized customer experiences. 3. **Modularity:** The system should be divided into well-defined modules with clear interfaces to promote code reusability and maintainability. Use interfaces to define contracts between modules and abstract away implementation details. 4. **Testability:** The code should be designed to be easily testable using unit tests and integration tests. Employ dependency injection to facilitate mocking and stubbing of dependencies during testing. 5. **Performance:** The system should be able to handle a large number of concurrent requests with minimal latency. Optimize data structures and algorithms to minimize processing time. Although low latency is desired, focus on algorithmic efficiency first. 6. **Scalability:** While we aren't building a distributed system, the class design should permit scaling within a single JVM process or migrating to a distributed architecture later if needed. (e.g. use interfaces.) ## Core Entities 1. **Customer:** Represents a customer waiting for a table. Attributes include: * `partySize`: The number of people in the customer's party. * `preferences`: A list of customer preferences (e.g., booth, high chair). * `contactNumber`: The customer's phone number for SMS notifications. * `joinTime`: The time the customer joined the waiting queue. * `status`: The current status of the customer (e.g., WAITING, NOTIFIED, SEATED, NO_SHOW). * `customerId`: Unique ID for customer object. 2. **Table:** Represents a table in the restaurant. Attributes include: * `tableId`: Unique identifier for the table. * `capacity`: The number of seats at the table. * `location`: The location of the table in the restaurant (e.g., near window, in corner). * `type`: The type of table (e.g., booth, high-top, regular). * `status`: The current status of the table (e.g., AVAILABLE, OCCUPIED, DIRTY, RESERVED). 3. **WaitingQueue:** Manages the queue of waiting customers. * `customers`: A data structure to store the waiting customers (e.g., a synchronized queue or list). * `queueManagementStrategy`: The strategy used to manage the queue (e.g., FIFO, priority-based). * Methods for adding customers to the queue, removing customers from the queue, and retrieving the next customer to be seated. 4. **TableManager:** Manages the tables in the restaurant. * `tables`: A data structure to store the tables (e.g., a list or map). * Methods for adding tables, removing tables, updating table status, and finding suitable tables for a given party size. 5. **NotificationService:** Sends notifications to customers (e.g., SMS notifications when their table is ready). This can be an interface to allow for different notification providers (e.g., Twilio, AWS SNS). 6. **QueueManagementStrategy:** An interface defining the strategy for managing the waiting queue. Implementations could include `FIFOQueueStrategy`, `PriorityQueueStrategy`, etc. 7. **Reservation:** Represent a pre-booked time slot. Attributes include: * `time`: Time slot for the reservation. * `customer`: The customer associated with reservation.

Design application for restaurant / malls to efficiently handle waiting queue and optimizely assign the table.

Requirements

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