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MAD II · Celery, queues, webhooks & SSE

19 questions · 51.5 marks · 4 papers

Answer key

Indian Institute of Technology Madras

BS Degree Programme · Examination & Study Paper

Modern Application Development II

Celery, queues, webhooks & SSE

Official Paper

Examination Instructions & Guidelines

Solve on notebook/paper first before checking solutions.
MCQ: Exactly 1 option is correct. Negative marking applies.
MSQ: One or more options correct. Select all to score.
Scientific calculator allowed for all calculations.
Official answer key is sealed at the end of this sheet.

End Term · 31 Aug 2025 (FN)End Term

Q1MCQ2 Marks·Choose one option
Asked 2 times Key ↓
In a message queue system, if the consumer is slower than the producer, what is likely to occur first?
1. AMessages will be dropped
2. BThe producer will block until the consumer is ready
3. CMessages will accumulate in the queue
4. DThe consumer will speed up automatically
Q2MSQ2 Marks·Choose all correct options
Asked 2 times Key ↓
Which of the following is/are the potential benefits of using a message broker?
1. AA message broker allows two servers in a network to directly communicate with each other, without an intermediary.
2. BA message broker makes the network scalable for adding more servers to the network.
3. CA message broker can be used for batch processing of messages.
4. DA message broker is not suited in case of traffic spikes, as messages are retained in the queue until processed.
Q3MSQ2 Marks·Choose all correct options
Asked 3 times Key ↓
Which statements about webhooks are correct?
1. AThey enable real-time data delivery
2. BThey require polling from the client
3. CThey use HTTP POST requests typically
4. DThey're designed for server-to-server communication
Q4MCQ3 Marks·Choose one option
Asked 2 times Key ↓
A popular e-commerce platform needs to notify multiple third-party services (inventory management, email marketing, analytics) whenever a customer places an order. The development team is considering different approaches to handle these notifications. Scenario: When an order is placed, the system needs to: ● Update inventory levels in an external warehouse system ● Send a welcome email through a third-party email service ● Log analytics data to an external tracking service ● Update customer loyalty points in a CRM system Which of the following statements about using webhooks for this scenario is MOST accurate?
1. AWebhooks are not suitable for this use case because they require the e- commerce platform to continuously poll each third-party service to check if they're ready to receive data, which would create unnecessary network overhead.
2. BWebhooks provide an ideal solution as they allow the e-commerce platform to push real-time notifications to all subscribed third-party services immediately when an order is placed, eliminating the need for these services to repeatedly poll for updates.
3. CWebhooks should be avoided in this scenario because they operate synchronously, meaning the customer's order placement would be delayed until all third-party services have successfully processed their notifications.
4. DWebhooks are primarily designed for read-only operations and cannot handle complex data payloads like order information, making them unsuitable for e-commerce transaction notifications.
Q5MSQ3 Marks·Choose all correct options
Asked 3 times Key ↓
Which statements are true about handling background tasks in Flask with Celery?
1. ACelery allows long-running tasks to be executed asynchronously
2. BPolling is a strategy to check task status periodically
3. CUsing time.sleep() blocks the event loop and is recommended for async tasks
4. DFlask + Celery + Redis is a common stack for async task management

End Term · 31 Aug 2025 (AN)End Term

Q6MCQ2 Marks·Choose one option
Asked 2 times Key ↓
In a message queue system, if the consumer is slower than the producer, what is likely to occur first?
1. AMessages will be dropped
2. BMessages will accumulate in the queue
3. CThe consumer will speed up automatically
4. DThe producer will block until the consumer is ready
Q7MSQ2 Marks·Choose all correct options
Asked 2 times Key ↓
Which of the following is/are the potential benefits of using a message broker?
1. AA message broker makes the network scalable for adding more servers to the network.
2. BA message broker allows two servers in a network to directly communicate with each other, without an intermediary.
3. CA message broker is not suited in case of traffic spikes, as messages are retained in the queue until processed.
4. DA message broker can be used for batch processing of messages.
Q8MSQ2 Marks·Choose all correct options
Asked 3 times Key ↓
Which statements about webhooks are correct?
1. AThey enable real-time data delivery
2. BThey use HTTP POST requests typically
3. CThey're designed for server-to-server communication
4. DThey require polling from the client
Q9MCQ3 Marks·Choose one option
Asked 2 times Key ↓
A popular e-commerce platform needs to notify multiple third-party services (inventory management, email marketing, analytics) whenever a customer places an order. The development team is considering different approaches to handle these notifications. Scenario: When an order is placed, the system needs to: ● Update inventory levels in an external warehouse system ● Send a welcome email through a third-party email service ● Log analytics data to an external tracking service ● Update customer loyalty points in a CRM system Which of the following statements about using webhooks for this scenario is MOST accurate?
1. AWebhooks are not suitable for this use case because they require the e- commerce platform to continuously poll each third-party service to check if they're ready to receive data, which would create unnecessary network overhead.
2. BWebhooks should be avoided in this scenario because they operate synchronously, meaning the customer's order placement would be delayed until all third-party services have successfully processed their notifications.
3. CWebhooks provide an ideal solution as they allow the e-commerce platform to push real-time notifications to all subscribed third-party services immediately when an order is placed, eliminating the need for these services to repeatedly poll for updates.
4. DWebhooks are primarily designed for read-only operations and cannot handle complex data payloads like order information, making them unsuitable for e-commerce transaction notifications.
Q10MSQ3 Marks·Choose all correct options
Asked 3 times Key ↓
Which statements are true about handling background tasks in Flask with Celery?
1. AUsing time.sleep() blocks the event loop and is recommended for async tasks
2. BCelery allows long-running tasks to be executed asynchronously
3. CPolling is a strategy to check task status periodically
4. DFlask + Celery + Redis is a common stack for async task management

End Term · 22 Dec 2024 (FN)End Term

Q11MCQ3 Marks·Choose one option
Asked 2 times Key ↓
Which of the following is true regarding long polling?
1. ALong polling opens multiple connections between the client and the server, and the server continuously sends updates to the client in real-time.
2. BLong polling involves the client repeatedly sending requests at fixed intervals to the server to check for updates, regardless of whether new data is available.
3. CLong polling allows the client to make a single request to the server, where the server holds the connection open until new data is available and then sends the response.
4. DLong polling uses WebSockets to maintain a persistent, bidirectional connection between the client and the server.

End Term · 22 Dec 2024 (AN)End Term

Q12MCQ3 Marks·Choose one option
Asked 2 times Key ↓
Which of the following is true regarding long polling?
1. ALong polling opens multiple connections between the client and the server, and the server continuously sends updates to the client in real-time.
2. BLong polling allows the client to make a single request to the server, where the server holds the connection open until new data is available and then sends the response.
3. CLong polling involves the client repeatedly sending requests at fixed intervals to the server to check for updates, regardless of whether new data is available.
4. DLong polling uses WebSockets to maintain a persistent, bidirectional connection between the client and the server.
Q13MCQ3 Marks·Choose one option
Key ↓
1. AII, III, I
2. BIII, I, II
3. CIII, II, I
4. DI, II, III
Q14MCQ2 Marks·Choose one option
Key ↓
You have a Celery task send_email that needs to run every 10 minutes. How can you schedule it?
1. AUsing @app.task_periodic to run the task every 10 minutes.
2. BUsing @app.on_periodic to schedule a periodic task.
3. CUsing Celery Beat to schedule periodic tasks.
4. DCelery doesn't support scheduling tasks at fixed intervals; you need to use an external scheduler.
Q15MCQ4.5 Marks·Choose one option
Key ↓
1. AThe task will immediately execute and print the result 'Task completed'.
2. BThe task will execute asynchronously, and 'Task completed' will be printed after a 10-second delay.
3. CThe task will execute synchronously, blocking the main thread for 10 seconds.
4. DNone of these
Q16MSQ3 Marks·Choose all correct options
Key ↓
Which of the following statements correctly describe the use of asynchronous messaging systems and frameworks?
1. ACelery allows web servers to offload long-running tasks to worker processes, decoupling task execution from user requests.
2. BPush queues are used for real-time operations, while pull queues are better suited for batch processing.
3. CServer-Sent Events (SSE) provide a persistent connection between server and client, enabling bi-directional communication.
4. DRedis is a high-performance in-memory database that supports Pub/Sub.
Q17MSQ3 Marks·Choose all correct options
Asked 3 times Key ↓
Which of the following statement(s) is/are true about Webhooks?
1. AA Webhook is a method for a server to send real-time data to another server as an HTTP POST request.
2. BWebhooks are typically used for sending periodic updates at regular intervals.
3. CA client must continuously poll a Webhook URL to receive data.
4. DWebhooks are usually used in event-driven architectures, where an event triggers an HTTP POST request to a specified endpoint.
Q18MSQ3 Marks·Choose all correct options
Key ↓
Which of the following statement(s) is/are true regarding Server-Sent Events (SSE) and WebSockets?
1. ASSE is a two-way communication protocol, while WebSockets are unidirectional.
2. BWebSockets are more suited for scenarios requiring bi-directional communication.
3. CSSE is based on HTTP and can only be used for server-to-client communication, while WebSockets are based on TCP and support both directions.
4. DSSE is an extension of WebSockets, providing enhanced support for server-to- client communication.
Q19MSQ3 Marks·Choose all correct options
Asked 3 times Key ↓
Which of the following is/are typical use case(s) for Celery tasks?
1. AProcessing time-consuming or resource-intensive background jobs asynchronously.
2. BDirectly handling incoming HTTP requests in web servers.
3. CScheduling periodic tasks like sending emails or cleaning up the database.
4. DServing real-time notifications over WebSockets.

Official Key

Master Answer Key & Explanations

Official answer keys from IIT Madras BS past papers. Click any question to review.

Reveal Key

Q1C

Q2B, C

Q3A, C, D

Q4B

Q5A, B, D

Q6B

Q7A, D

Q8A, B, C

Q9C

Q10B, C, D

Q11C

Q12B

Q13B

Q14C

Q15B

Q16A, B, D

Q17A, D

Q18B, C

Q19A, C

Questions and answer keys are reproduced from the official IIT Madras BS papers. Topics and repeated question types are BTechi’s own grouping. BTechi is not affiliated with IIT Madras.