Requirements

Let's refine our Live Auction Platform, envisioned for high-stakes scenarios like IPL and EPL player auctions. We're aiming to build a robust, scalable, and thread-safe system capable of handling concurrent bidding from numerous participants. Imagine the intense pressure of a live auction – every bid, every update, must be processed swiftly and accurately. Incorrect bid placement, delays, or inconsistencies in displaying auction state can significantly impact the fairness and excitement of the event. This platform needs to manage multiple auctions concurrently, each with its own set of participants, items, and rules. The auction process involves displaying item details, accepting bids, determining the winning bidder, and updating the auction status in real-time. Furthermore, the system must handle edge cases such as invalid bids, network latency, and potential race conditions. # Requirements ## Functional Requirements 1. **Auction Creation and Management:** * Ability to create new auctions with specific parameters: * Auction ID (unique identifier) * Item Description (e.g., Player Name, Team) * Base Price * Auction Start Time * Auction End Time * Currency * Increment Amount (minimum bid increase) * Auction Type (e.g., Highest Bid, Sealed Bid) * Ability to schedule and start/stop auctions. * Support for different auction types (e.g., English Auction, Sealed Bid Auction). Each type should have different bidding rules and winning criteria. * Administrative interface to monitor and manage ongoing auctions. 2. **Bidding Functionality:** * Participants can place bids on items being auctioned. * The system validates bids based on auction rules (e.g., minimum increment, bid amount greater than current highest bid). * Support concurrent bidding from multiple participants. * Provide real-time feedback to participants on the status of their bids (accepted, rejected, outbid). * Implement a bidding strategy that can be customized based on the type of auction (e.g., a proxy bidding strategy for automatically increasing bids). 3. **Auction State Management:** * Maintain a consistent and up-to-date state of each auction, including: * Current highest bid * Highest bidder * Remaining time * List of all bids (for auditing purposes) * Provide real-time updates to all participants on the auction state. * Persist auction state to prevent data loss in case of system failure (consider simple file persistence for this LLD). 4. **User Management:** * Register and authenticate users. * Assign roles to users (e.g., bidder, administrator). * Manage user profiles and preferences. 5. **Notifications:** * Notify participants when they are outbid. * Notify the winning bidder at the end of the auction. * Notify administrators of any errors or anomalies. ## Non-Functional Requirements 1. **Thread Safety:** The system must be thread-safe to handle concurrent bidding from multiple participants without data corruption or race conditions. Pay close attention to synchronization and locking mechanisms. 2. **Extensibility:** The system should be designed to easily accommodate new auction types, bidding strategies, and notification methods without requiring significant code changes. Design Patterns are key here. 3. **Modularity:** The system should be divided into well-defined modules with clear interfaces to promote code reuse and maintainability. This makes testing easier. 4. **Testability:** The system should be designed to facilitate unit testing and integration testing. Favor dependency injection to mock dependencies for testing. 5. **Concurrency:** The auction engine should handle a large number of concurrent bids efficiently. Use appropriate data structures and algorithms to minimize contention. 6. **Real-time Updates:** The system should provide real-time updates to participants with minimal latency. Consider using a push-based mechanism (e.g., WebSockets - abstract this). 7. **Fault Tolerance:** The system should be resilient to failures and able to recover from errors gracefully. Implement appropriate error handling and logging mechanisms. For this LLD, focus on in-memory recovery; persistence is secondary. ## Core Entities 1. **Auction:** Represents a single auction event. Key attributes include: `auctionId`, `item`, `basePrice`, `startTime`, `endTime`, `auctionType`, `currentHighestBid`, `currentHighestBidder`. It is responsible for managing bids, determining the winner, and updating the auction state. The different `AuctionType` will need different winning conditions. 2. **Bid:** Represents a bid placed by a participant. Key attributes include: `bidderId`, `amount`, `timestamp`. Bid objects should be immutable. 3. **Participant:** Represents a user participating in the auction. Key attributes include: `userId`, `name`, `email`. 4. **Item:** Represents the item being auctioned. Key attributes include: `itemId`, `description`, `imageUrl`. 5. **AuctionEngine:** Orchestrates the auction process, managing multiple auctions, processing bids, and updating auction states. This is the core component. 6. **BidValidator:** Validates bids based on the auction rules. This encapsulates bidding logic (e.g., minimum increment, bid amount). This uses the Strategy Pattern to handle different bid validation logic depending on Auction Type. 7. **AuctionState:** Represents the current state of the auction. It is an immutable snapshot. 8. **NotificationService:** Sends notifications to participants and administrators. This can be extended easily.

Design Live Auction platform for IPL / EPL.

Requirements

Interview Simulation

Functional Requirements

💡 Interview Tip

Non-Functional Requirements

Core Entity Identification

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