Design the system architecture to support a last minute ticket sales app. We want to launch a mobile app that lets us sell last minute(day of) tickets to nearby events(concerts, sporting events, etc.). Ask the candidate to start by identifying the major components of the architecture.
To design the architecture for a last minute ticket sales app, we would need to consider the following major components:
Mobile app: This is the user-facing component of the system that allows users to browse and purchase tickets to nearby events on their mobile devices.
Event database: This component stores information about the various events that are available for ticket purchase, including details such as the event name, location, date, and time.
Ticket inventory database: This component maintains a record of the available tickets for each event, as well as the corresponding price and any other relevant details.
Payment processing: This component handles the payment processing for ticket purchases, including the secure transmission of payment information and the processing of payment transactions.
Push notifications: This component allows the system to send push notifications to users who have purchased tickets, providing them with updates on the status of their ticket purchase and any other relevant information.
Geolocation: This component uses the user's device's GPS capabilities to determine their location and provide them with a list of nearby events.
User accounts: This component manages user accounts and provides users with the ability to securely log in and manage their account details, including the ability to purchase and manage tickets.
Can you show me the main components in a flow chart?
Sure, here is a simple flow chart that shows the main components of a last minute ticket sales app:
+-----------------+
| |
| Mobile App |
| |
+-----------------+
|
|
v
+----------------+ | +----------------+
| | | | |
| Event Database | | | Ticket Inventory|
| | | | Database |
+----------------+ | +----------------+
|
|
v
+----------------+ | +----------------+
| | | | |
| Payment | | | Push Notifications|
| Processing | | | |
| | | +----------------+
+----------------+ |
|
|
v
+----------------+ |
| | |
| Geolocation | |
| | |
+----------------+ |
|
|
v
+----------------+ |
| | |
| User Accounts | |
| | |
+----------------+ |
|
|
v
+-----------------+
| |
| Ticket Purchase |
| Confirmation |
| |
+-----------------+
In this flow chart, the mobile app is the main entry point for users, who can use it to browse and purchase tickets to nearby events. The event and ticket inventory databases provide information about the available events and tickets, while the payment processing component handles the payment processing for ticket purchases. The push notifications component allows the system to send notifications to users, and the geolocation component uses the user's location to provide them with a list of nearby events. Finally, the user accounts component manages user accounts and provides users with the ability to log in and manage their tickets.
What technologies should we consider for the event database considering the requirements?
To meet the requirements of a last minute ticket sales app, the event database should be able to store and manage a large amount of information about various events, including details such as the event name, location, date, and time. It should also be able to quickly retrieve and serve this information to the mobile app in real-time.
One technology that could be considered for the event database is a scalable, high-performance database system such as a distributed NoSQL database. NoSQL databases are designed to store and manage large amounts of data, and are particularly well-suited for real-time data retrieval. This would allow the database to quickly serve the necessary information to the mobile app, ensuring that users can access the latest information about nearby events.
Other technologies that could be considered for the event database include traditional relational database management systems (RDBMS) and cloud-based database services, such as Amazon DynamoDB or Google Cloud Firestore. These technologies offer similar capabilities and could also be used to support the requirements of the last minute ticket sales app.
How would you handle displaying a large amount of tickets?
To handle the display of a large amount of tickets in a last minute ticket sales app, there are a few different approaches that could be taken.
One approach would be to implement pagination, which allows the app to display the tickets in smaller, manageable chunks or "pages". The app could then provide users with the ability to navigate between these pages, allowing them to view and purchase tickets as needed.
Another approach would be to use filters and sorting options to allow users to narrow down the list of available tickets. For example, the app could provide users with the ability to filter tickets by event type, location, price, or other relevant criteria. This would allow users to quickly find the tickets they are interested in, without having to browse through a large number of irrelevant tickets.
Another approach that could be used is to implement "lazy loading", which allows the app to only load a small number of tickets initially, and then load additional tickets as the user scrolls down the list. This allows the app to display a large number of tickets without overloading the user's device or network connection.
Overall, there are a number of different approaches that could be taken to handle the display of a large number of tickets in a last minute ticket sales app, and the best approach will depend on the specific requirements and constraints of the app.
How do you notify the customers that an event is on sale? What complexity does this introduce in the design?
To notify customers that an event is on sale in a last minute ticket sales app, one approach would be to use push notifications. Push notifications are messages that are sent directly to a user's mobile device, and can be used to alert users to a variety of different events, including the availability of new tickets.
To implement push notifications, the app would need to be configured to receive and handle push notifications from a push notification server. The server would be responsible for sending the notifications to the app, and the app would be responsible for displaying the notifications to the user.
The complexity introduced by push notifications in the design of the app would primarily revolve around the implementation and management of the push notification server, as well as the integration of the push notification functionality into the app itself. This would require careful planning and coordination to ensure that the push notifications are delivered reliably and in a timely manner.
Additionally, the use of push notifications would also require the app to collect and manage user preferences for push notifications, as well as provide users with the ability to opt-in or opt-out of receiving push notifications. This would add an additional layer of complexity to the design, as it would require the app to provide user-facing controls for managing push notification preferences.
How do you protect your service from overselling the tickets?
To protect a last minute ticket sales app from overselling tickets, there are a few different approaches that could be taken.
One approach would be to implement strict controls on the availability of tickets in the ticket inventory database. This would involve maintaining a record of the total number of tickets available for each event, as well as the number of tickets that have been sold. The app could then be configured to only allow users to purchase tickets if there are still available tickets in the inventory.
Another approach would be to implement a real-time synchronization mechanism between the ticket inventory database and the payment processing component. This would ensure that the payment processing component is always aware of the latest ticket availability information, and can prevent users from purchasing tickets that are no longer available.
Finally, the app could also implement a queueing system for ticket purchases. This would allow users to place a "hold" on tickets that are currently unavailable, and then automatically purchase the tickets when they become available. This would prevent overselling, while also providing a fair and transparent mechanism for users to purchase tickets.
Overall, there are a number of different approaches that could be taken to protect a last minute ticket sales app from overselling tickets, and the best approach will depend on the specific requirements and constraints of the app.
What user experience would you provide if a user tries to buy a ticket and gets an error from backend?
If a user tries to buy a ticket and gets an error from the backend, it is important to provide a clear and user-friendly experience that helps the user understand what went wrong and what they can do to resolve the issue.
One approach to providing a good user experience in this situation would be to display an error message to the user that clearly explains the issue and provides them with specific instructions for how to resolve it. For example, if the issue is due to an issue with the payment processing, the error message could provide the user with details about the payment issue and provide them with instructions for how to update their payment information.
Another important aspect of providing a good user experience in this situation would be to make sure that the error message is displayed in a clear and concise manner, without overwhelming the user with unnecessary information. Additionally, it would be important to provide the user with clear instructions for how to resolve the issue, and to make sure that the instructions are easy to follow.
Overall, the key to providing a good user experience in the case of a backend error is to provide the user with clear and concise information about the issue, as well as easy-to-follow instructions for how to resolve it. This will help to ensure that the user is able to quickly and easily resolve the issue and continue with their ticket purchase.
What if it's a Taylor Swift concert? How do we handle such a sudden rush of users?
If there is a sudden rush of users trying to purchase tickets for a Taylor Swift concert, it is important to have a system in place that can handle the increased demand. This will require a scalable and high-performance architecture that can quickly and reliably process a large number of requests from users.
One approach to handling a sudden rush of users for a Taylor Swift concert would be to implement a distributed system architecture, using a combination of load balancers, caching, and other techniques to distribute the workload across multiple servers and reduce the response time for users. This would allow the system to handle a large number of concurrent users without slowing down or becoming unresponsive.
Another approach would be to implement a real-time synchronization mechanism between the ticket inventory database and the payment processing component. This would ensure that the payment processing component is always aware of the latest ticket availability information, and can prevent users from purchasing tickets that are no longer available.
Additionally, the app could also implement a queueing system for ticket purchases, which would allow users to place a "hold" on tickets that are currently unavailable and then automatically purchase the tickets when they become available. This would prevent overselling and provide a fair and transparent mechanism for users to purchase tickets.
Overall, there are a number of different approaches that could be taken to handle a sudden rush of users for a Taylor Swift concert, and the best approach will depend on the specific requirements and constraints of the app.
Can you go into detail about how one would implement a distributed system architecture? What specific technologies would you use?
To implement a distributed system architecture for a last minute ticket sales app, there are a few different technologies and approaches that could be used.
One approach would be to use a load balancer to distribute incoming requests from users across multiple server instances. This would allow the system to handle a large number of concurrent users without overloading any individual server.
Another approach would be to use a distributed cache, such as Redis or Memcached, to store frequently accessed data, such as the list of available tickets for each event. This would allow the app to quickly retrieve this information from the cache, reducing the response time for users and improving the overall performance of the app.
Another technology that could be used in a distributed system architecture is a distributed database, such as MongoDB or Cassandra. This would allow the app to store and manage its data across multiple server instances, providing increased scalability and performance.
Overall, there are a number of different technologies and approaches that could be used to implement a distributed system architecture for a last minute ticket sales app. The specific technologies and approaches that are used will depend on the specific requirements and constraints of the app.
Because users will want to get through the ticket-buying process as quickly as possible, how could payment information be saved for future purchases?
To allow users to quickly complete the ticket-buying process for future purchases, the app could implement a feature that allows users to save their payment information for future use.
One approach to implementing this feature would be to provide users with the option to save their payment information when they make their first ticket purchase. The app could then securely store this information in the user's account, allowing them to easily access and use it for future purchases.
Another approach would be to use a third-party payment processing service, such as PayPal or Stripe, which provides users with the option to securely save their payment information for future use. This would allow users to quickly and easily make future ticket purchases without having to re-enter their payment information.
Overall, there are a number of different approaches that could be taken to allow users to quickly and easily complete the ticket-buying process for future purchases. The specific approach that is used will depend on the specific requirements and constraints of the app.
Could we show users how many others are viewing a ticket to incentivize purchases? How could this be done?
To incentivize ticket purchases, the app could show users how many other users are currently viewing a particular ticket. This could be done by implementing a real-time tracking mechanism that allows the app to track the number of users who are currently viewing each ticket, and then displaying this information to users as they browse the available tickets.
To implement this feature, the app would need to maintain a real-time record of the number of users who are currently viewing each ticket. This could be done using a distributed cache, such as Redis or Memcached, which allows the app to quickly and efficiently store and retrieve this information.
When a user views a particular ticket, the app could then retrieve the current number of users who are viewing that ticket from the cache, and display this information to the user. This would provide users with a sense of the level of interest in the ticket, and could incentivize them to make a purchase if they see that a large number of other users are also viewing the ticket.
Overall, showing users how many others are viewing a particular ticket could be a useful way to incentivize ticket purchases, and could be implemented using a real-time tracking mechanism and a distributed cache.
Are there ethical reasons not to do this
There could be some ethical concerns around showing users how many others are viewing a particular ticket, as it could potentially create a sense of urgency or pressure for users to make a purchase. This could lead to users making impulsive or irrational decisions, and could potentially result in them overspending or purchasing tickets that they may not have otherwise considered.
Additionally, showing users how many others are viewing a particular ticket could also create a competitive or confrontational atmosphere, which could be unpleasant for users and could potentially lead to conflict.
Overall, while showing users how many others are viewing a particular ticket could potentially be a useful way to incentivize ticket purchases, it is important to consider the potential ethical implications of this approach and to carefully weigh the potential benefits against the potential drawbacks.
