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migration_to_v2.md

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Changes in major version 2

Ditching global Configuration class

In the major version 1.* of the library, the configuration was passed to the factory method FingerprinterFactory.getInstance(context, configuration). Then if you wanted to get multiple fingerprints of different versions (e.g. in order to migrate to a newer version of fingerprint) you had to call getInstance method twice making it both ineffective and inconvenient.

In the major version 2, the version is passed to getDeviceId(..) and getFingerprint(..) methods.

Ditching SignalGroupProvider class

In the major version 1.* of the library, if you wanted to retrieve any particular signal involved in fingerprinting, you had to do the following:

  1. Call Fingerprinter.getFingerprint(stabilityLevel, listener) to retrieve FingerprintResult
  2. Call FingerprintResult.getSignalProvider to retrieve a signal provider a signal belongs to, e.g., HardwareSignalGroupProvider
  3. Get RawData from that particular signal provider, e.g., HardwareFingerprintRawData
  4. Get signal from that RawData, e.g., HardwareFingerprintRawData.manufacturerName()

To do the same thing in major version 2, you have to do the following:

  1. Call Fingerprinter.getFingerprintingSignalsProvider()
  2. Call fingerprintingSignalsProvider.manufacturerNameSignal

This approach requires less code and does not involve unnecessary fingerprints calculation. Also, it allows to reduce the complexity of the code base by making signal's hierarchy flat, i.e. not dividing signals into different signal groups based on their nature.

Introducing API for custom fingerprinting

The new method Fingerprinter.getFingerprint(fingerprintingSignals, hasher) allows you to create fingerprints based on whatever signals you want. In order to get signals first, use FingerprintingSignalsProvider class. See the example in the Full API reference

Changing behaviour of the factory method

We have removed configuration parameter from the factory method and changed it's behaviour. This is why now we have FingerprinterFactory.create(context) method instead of FingerprinterFactory.getInstance(context, configuration) method.

Whereas the latter method always returned the same instance given the same configuration, the former always returns a new instance of Fingerprinter. This may be useful if you want to calculate the fingerprint from scratch multiple times.

Caveats

Even though all the changes listed above are aimed towards making the API both more flexible and more convenient at the same time, there is one scenario of the API v1 usage that cannot be easily migrated to API v2.

If you intentionally operated with a whole group of signals using SignalGroupProvider.fingerprint(..) method or RawData.signals() method, then there is no alternative "one-liner" to do the same thing in API v2, because we decided to get rid of of signals grouping, as described in this section. Therefore, the only alternative when using API v2 is to manually get all the signals you want using FingerprintingSignalsProvider and then do with them whatever is needed, e.g. calculate a custom fingerprint.