City 311 needs live queue-depth metrics from event streams into Databricks. Which Azure messaging source should feed the pipeline?

City 311 live queue-depth metrics from event streams into Databricks should be fed by Azure Event Hubs. Event Hubs is the Azure messaging source for high-throughput municipal event streams that Databricks Structured Streaming can consume for live queue-depth and similar operational metrics. Live digital 311 events need a real streaming broker path rather than Event Grid streaming 311 events or Queue Storage streaming 311 events into Databricks for live queue-depth metrics.

Azure Service Bus queues streaming 311 events into Databricks for live queue-depth metrics are built for reliable ordered messaging, not the high-throughput live stream Databricks Structured Streaming needs for live queue-depth metrics. Azure Queue Storage streaming 311 events into Databricks for live queue-depth metrics is still a polled batch store, not a streaming broker, and cannot drive second-level or minute-level queue depth. Azure Event Grid streaming 311 events into Databricks for live queue-depth metrics is designed for discrete event routing, not continuous stream processing, so it abandons measurement and hides overload until citizens complain.

Exam caveat: Event Hubs is the streaming source; Databricks still needs a streaming reader, checkpointing, and a metrics sink—naming Event Hubs alone does not finish the pipeline design for trustworthy ops KPIs. Operational check: stream 311 events from Event Hubs into Databricks, compute live queue-depth aggregations into a serving table or dashboard, validate against a known test load, confirm latency meets ops needs, and reject Service Bus queues streaming, Queue Storage streaming, or Event Grid streaming 311 events into Databricks for live queue-depth metrics as substitutes for the event path.