2017-07-05 11:16:47 +00:00
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.. highlight:: kotlin
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Writing a custom notary service
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===============================
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.. warning:: Customising a notary service is an advanced feature and not recommended for most use-cases. Currently,
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customising Raft or BFT notaries is not yet fully supported. If you want to write your own Raft notary you will have to
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implement a custom database connector (or use a separate database for the notary), and use a custom configuration file.
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Similarly to writing an oracle service, the first step is to create a service class in your CorDapp and annotate it
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with ``@CordaService``. The Corda node scans for any class with this annotation and initialises them. The only requirement
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2017-10-09 09:44:32 +00:00
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is that the class provide a constructor with a single parameter of type ``AppServiceHub``.
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2017-07-05 11:16:47 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net/corda/docs/CustomNotaryTutorial.kt
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:language: kotlin
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:start-after: START 1
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:end-before: END 1
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The next step is to write a notary service flow. You are free to copy and modify the existing built-in flows such
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as ``ValidatingNotaryFlow``, ``NonValidatingNotaryFlow``, or implement your own from scratch (following the
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``NotaryFlow.Service`` template). Below is an example of a custom flow for a *validating* notary service:
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.. literalinclude:: example-code/src/main/kotlin/net/corda/docs/CustomNotaryTutorial.kt
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:language: kotlin
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:start-after: START 2
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:end-before: END 2
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