You are designing Azure Functions for three different backend workloads.

Return an immediate response to a client: HTTP trigger

Process background work from a queue: Queue Storage trigger

Run code on a fixed schedule: Timer trigger

Use an HTTP trigger when a function must be invoked by an HTTP request and return a response directly to the calling client. Microsoft documents HTTP triggers as the standard mechanism for building serverless APIs and handling web requests or webhooks. This makes the HTTP trigger the correct fit for synchronous request-response workloads.

For asynchronous background processing, use an Azure Queue Storage trigger . A queue-triggered function runs when messages are added to an Azure Storage queue. This decouples the producer from the consumer and is appropriate for background processing where work can be buffered and processed independently of the original request. Microsoft also documents target-based scaling for Queue Storage triggers on supported Azure Functions hosting plans.

For scheduled execution, use a Timer trigger . Microsoft states that a timer trigger runs a function according to a configured schedule, typically expressed with an NCRONTAB/CRON expression. This makes it the correct choice for periodic maintenance, scheduled synchronization, reporting, or other fixed-time workloads.

Event Grid and Blob Storage triggers are event-driven mechanisms for event notifications and blob changes respectively, but neither matches these three stated dispatching requirements.

Study Guide references: Azure Functions → HTTP triggers; Queue Storage triggers; Timer triggers; event-driven and scheduled execution.