# A vendor drops files into SFTP at irregular times

Canonical URL: <https://datadriven.io/problems/a-vendor-drops-files-into-sftp-at-irregular-times-the-pipel-cb5bc3f3>

Domain: Pipeline Design · Difficulty: medium

## Problem

A vendor drops files into SFTP at irregular times. The pipeline currently has no boundary check; the orchestrator just starts at a fixed time and hopes the file is there. Apply the sensor-placement framing this section just taught and add a sensor at the boundary between the orchestrator and the external SFTP source. The structural footprint of a boundary sensor is a quality_check node (Monte Carlo, Bigeye, Anomalo, or dbt tests) sitting between the SFTP source and the daily Spark transform; the quality_check verifies the file landed correctly and is non-empty before the downstream pipeline proceeds. Sensors earn their place at the orchestrator/external-world boundary; the quality_check is the canvas's representation of that role.

## Related

- [All practice problems](https://datadriven.io/problems)
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- [Daily Challenge](https://datadriven.io/daily)

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