System requirements

Functional:

• User Registration and Authentication:
• Implement strong password hashing algorithms (e.g., bcrypt) for secure password storage.
• Integrate with social login providers (e.g., Google, Facebook) for a convenient user experience (optional).
• View Market Data:
• Allow users to filter and customize market data views (e.g., watchlists, specific exchanges).
• Integrate with charting libraries for advanced technical analysis tools.
• Display news feeds and economic data relevant to specific stocks or sectors.
• Place Orders:
• Allow users to specify order quantities and durations (e.g., Day Orders, Good Til Cancelled)
• Implement advanced order types like trailing stop-loss and iceberg orders (for sophisticated traders).
• Portfolio Management:
• Integrate with market data feeds to provide real-time portfolio valuation.
• Allow users to download transaction history and performance data in various formats (e.g., CSV, PDF).
• Offer basic portfolio rebalancing tools and investment strategy suggestions (optional).
• Real-Time Notifications:
• Allow users to customize notification preferences (e.g., email, SMS, in-app alerts) for different events.
• Integrate with communication platforms like web sockets for real-time push notifications with minimal latency.

Non-Functional:

• Performance:
• Define latency targets for order processing and market data updates (e.g., milliseconds for order execution).
• Implement performance monitoring tools and dashboards for continuous system optimization.
• Scalability:
• Design the system using message queues and asynchronous processing to handle high volumes of concurrent users.
• Utilize cloud-based infrastructure with auto-scaling capabilities to accommodate spikes in trading activity.
• Reliability:
• Implement redundant data storage across geographically distributed servers to ensure high availability.
• Design the system with disaster recovery plans in place to minimize downtime in case of outages.
• Security:
• Enforce secure communication protocols (e.g., HTTPS) for all data transmission.
• Implement multi-factor authentication (MFA) as a mandatory security layer for all user accounts.
• Regularly conduct security audits and penetration testing to identify and address vulnerabilities.
• Compliance:
• Integrate with KYC/AML verification services to comply with anti-money laundering regulations.
• Maintain detailed audit logs of all user activities and transactions for regulatory reporting purposes.
• Design the platform to be adaptable to future regulatory changes.

By elaborating on these requirements, we provide a clearer picture of the functionalities and performance expectations for the trading platform. This detailed breakdown helps guide the design and development process to ensure a user-friendly, secure, and reliable trading experience.

Capacity estimation

Estimate the scale of the system you are going to design...

API design

The real-time stock trading platform will require a well-defined set of APIs to facilitate communication between different components and potentially external applications. Here's a breakdown of some key expected APIs:

1. User Management APIs:

• Register User: Allows users to create new accounts with username, password, and other relevant information.
• Login User: Validates user credentials and provides authentication tokens for accessing other APIs.
• Get User Profile: Retrieves user information like account details, preferences, and settings.
• Update User Profile: Enables users to update their profile information.

2. Market Data APIs:

• Get Real-time Quotes: Provides real-time market data for specific stocks or indices, including price, volume, and change.
• Get Historical Data: Retrieves historical price data for a specified period.
• Get Order Book: Retrieves the current order book for a specific stock, showing buy and sell orders at different price levels.
• Subscribe to Market Data: Allows users to subscribe to real-time updates for specific stocks or market data feeds.

3. Order Management APIs:

• Place Order: Submits an order to buy or sell a security, specifying order type (market, limit, stop-loss, etc.), quantity, and price (if applicable).
• Cancel Order: Allows users to cancel an existing order before it's filled.
• Get Order Status: Retrieves the current status of an order (pending, filled, cancelled).
• Get Order History: Provides a list of past orders placed by the user.

4. Portfolio Management APIs:

• Get Portfolio Positions: Retrieves user's current holdings and their corresponding quantities and market values.
• Get Portfolio Performance: Provides performance metrics like total return, realized and unrealized P/L.
• Download Transaction History: Allows users to download a history of their transactions in a specified format.

5. Notification APIs:

• Subscribe to Notifications: Enables users to subscribe to real-time notifications for order updates, price alerts, and market events.
• Send Notification: (Internal API) Used by other components to trigger notifications based on specific events (e.g., order execution, price threshold reached).

Security Considerations:

• All APIs should be authenticated using secure tokens obtained through user login.
• Implement rate limiting to prevent abuse and ensure system stability under high load.
• Validate and sanitize user input to prevent security vulnerabilities like injection attacks.

Additional APIs:

• Depending on platform features, additional APIs might be needed for functionalities like:
• Managing watchlists
• Accessing news feeds and economic data
• Integrating with external charting tools (optional)

By defining a well-structured set of APIs, we ensure clear communication between different components and enable potential integration with external applications. Remember, this is a high-level overview, and specific API details like request parameters and response formats will be defined during the development process.

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

High-level design

here's a high-level design for the real-time stock trading platform, identifying the key components needed for a complete end-to-end solution:

User Interface (UI):

• Provides a user-friendly interface for users to interact with the platform.
• Allows users to search for stocks, view market data, place orders, manage portfolios, and receive notifications.
• Ensures a responsive and secure user experience.

User Management Service:

• Handles user registration, login, and authentication.
• Stores user information securely.
• Integrates with KYC/AML verification services for compliance.

Market Data Service:

• Retrieves real-time market data from exchanges and financial data providers.
• Provides users with stock quotes, order book depth, historical data, and news feeds.
• Utilizes message queues and caching mechanisms for efficient data delivery.

Order Management System (OMS):

• Processes user orders for buying and selling stocks.
• Integrates with the Risk Management component to evaluate risk before order execution.
• Routes orders to the appropriate exchange or execution venue.
• Manages order lifecycles (placement, modification, cancellation, and execution).

Trade Execution Engine:

• Executes orders in the market by interacting with exchanges or other execution venues.
• Ensures best execution practices to get users the best possible price.
• Handles order rejections and partial fills.

Risk Management Service:

• Evaluates potential risks associated with user orders based on pre-defined risk limits and user profiles.
• May consider factors like portfolio exposure, margin usage, and order size.
• Can reject orders that exceed risk thresholds or suggest alternative strategies.

Portfolio Management Service:

• Tracks user holdings and calculates portfolio performance.
• Provides users with real-time updates on their portfolio value and P/L.
• Offers functionalities like transaction history download and basic portfolio rebalancing tools (optional).

Notification Service:

• Sends real-time notifications to users about order executions, price alerts, and important market events.
• Utilizes push notifications and email to ensure timely delivery.
• Allows users to customize notification preferences.

Compliance Service:

• Ensures adherence to all relevant financial regulations (KYC, AML, etc.).
• Manages audit logs for user activity and transactions for reporting purposes.
• May integrate with external compliance services for regulatory checks.

Data Storage:

• Stores user data, market data, order history, and other platform information securely.
• Utilizes a scalable and reliable database solution to handle high data volumes.
• May implement data redundancy across geographically distributed servers for high availability.

Administration Console:

• Provides an interface for administrators to monitor system health, manage user accounts, and configure platform settings.
• Allows for risk parameter adjustments and user management.

Communication Interfaces:

• APIs for communication between different components within the platform.
• May include APIs for external integrations with charting tools or news feeds (optional).

Security Measures:

• Secure communication protocols (HTTPS) for all data transmission.
• Encryption of sensitive user data at rest and in transit.
• Regular security audits and penetration testing to identify and address vulnerabilities.
• User access controls and multi-factor authentication (MFA) for added security.

This high-level design provides a comprehensive overview of the key components needed for a real-time stock trading platform. Each component can be further elaborated on during the detailed design phase, defining specific functionalities, data structures, and communication protocols. By having a well-defined architecture, you can ensure a robust, secure, and scalable platform that meets the demands of modern stock trading.

Request flows

Here is the sequence diagram for Search Stock and Get Current Price

Here is the sequence diagram for Placing an Order

Here is the sequence diagram for Getting Order Confirmation

Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...

Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...

Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.

Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?