corda/docs/source/tutorial-custom-notary.rst

Writing a custom notary service (experimental)

Warning

Customising a notary service is still an experimental feature and not recommended for most use-cases. The APIs for writing a custom notary may change in the future.

The first step is to create a service class in your CorDapp that extends the NotaryService abstract class. This will ensure that it is recognised as a notary service. The custom notary service class should provide a constructor with two parameters of types ServiceHubInternal and PublicKey. Note that ServiceHubInternal does not provide any API stability guarantees.

../../samples/notary-demo/workflows/src/main/kotlin/net/corda/notarydemo/MyCustomNotaryService.kt

The next step is to write a notary service flow. You are free to copy and modify the existing built-in flows such as ValidatingNotaryFlow, NonValidatingNotaryFlow, or implement your own from scratch (following the NotaryFlow.Service template). Below is an example of a custom flow for a validating notary service:

../../samples/notary-demo/workflows/src/main/kotlin/net/corda/notarydemo/MyCustomNotaryService.kt

To enable the service, add the following to the node configuration:

notary : {
    validating : true # Set to false if your service is non-validating
    className : "net.corda.notarydemo.MyCustomValidatingNotaryService" # The fully qualified name of your service class
}

Testing your custom notary service

To create a flow test that uses your custom notary service, you can set the class name of the custom notary service as follows in your flow test:

../../testing/node-driver/src/test/kotlin/net/corda/testing/node/CustomNotaryTest.kt

After this, your custom notary will be the default notary on the mock network, and can be used in the same way as described in flow-testing.