Developing Solutions for Microsoft Azure (AZ-204) Practice Exam

What application pattern is used for a durable function that monitors a resource until a specific condition is met?

1. Function chaining

2. Fan out/fan in

3. Monitor

4. Event-triggered

The correct answer is: Monitor

The application pattern used for a durable function that monitors a resource until a specific condition is met is the Monitor pattern. This pattern is specifically designed to support scenarios where a long-running function needs to continually check the state of a resource, ensuring that it only proceeds when the necessary conditions are satisfied. In practical terms, this could involve a durable function repeatedly polling an API, checking a database for status updates, or monitoring a service to see if a required event has occurred. The key aspect of this pattern is its ability to handle the waiting period in a reliable manner without consuming resources unnecessarily, effectively integrating waiting and monitoring into the workflow. Other patterns serve different purposes. Function chaining is ideal for tasks that are executed in a linear sequence, enabling a direct flow from one function to the next. Fan out/fan in is designed for parallel execution where multiple functions can process data simultaneously, followed by a consolidation phase. Event-triggered patterns focus on responding to specific events without a constant monitoring requirement. Each of these patterns serves its purpose, but for monitoring resources until certain conditions are met, the Monitor pattern is the appropriate choice.