Supporting multiple fingerprint sensors

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One of the goals of Windows Biometric Framework (WBF) is to enable a single machine to support multiple sensors. While the majority of computers in the near term will have only a single sensor, it is important for your fingerprint management application (FMA) to support multiple sensors.

This information applies to the following operating systems:

  • Windows Server 2008 R2
  • Windows 7

When multiple fingerprint sensors are installed on a system, your FMA should start for a specific biometric unit.

When Control Panel invokes the command to start your FMA, it expands %{biounitid} to the unit ID of the sensor that your FMA should use for the enrollment. For information about the biounitid, see FMA Registration.

Your FMA should do the following to ensure that it works correctly on both single sensor and multi-sensor machines:

  1. When it calls WinBioEnrollBegin, specify the selected biometric unit ID so that the enrollment is stored for the correct sensor.

  2. Enumerate which fingerprints are enrolled so it can show this in the user interface. It should show only the fingerprints that are enrolled for the specified sensor.

  3. Let the user select which sensor to enroll on when there are multiple sensors and no biounitid is specified. This feature is optional but it would provide a consistent user experience. If there are multiple sensors on a system, the WBF displays the Touch a fingerprint reader to enroll your fingerprints page in Control Panel. See the following figure.

Implementing the features listed above enables your FMA to support multiple sensors and to be sensor agnostic. To give user context, the FMA can target only one sensor at a time.

A user might generate input on a sensor other than the sensor that your FMA is currently handling. Your FMA should handle such input gracefully:

  • Your FMA might ignore the other inputs, or it might allow the user to abandon their current enrollment and change to the new sensor.

  • If your FMA is a global FMA, it should detect whether the user has enrolled fingerprints on another sensor to show the user what fingerprints are enrolled on which sensor.

Enrollment

A global FMA must ensure that the enrollment wizard works with all sensors.

Designing Windows Biometric Framework Fingerprint Management Applications

 

 

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