04.1-file-transfer-listener

Implement a simple transfer listener

In this sample, we build upon the file transfer sample to add functionality to react to transfer completion on the consumer connector side.

We will use the provider from the file transfer sample, and the consumer built on the consumer from that sample, with a transfer process listener added.

Also, in order to keep things organized, the code in this example has been separated into several Java modules:

• consumer: this is where the extension definition and dependencies reside for the consumer connector
• listener: contains the TransferProcessListener implementation

Create the listener

A TransferProcessListener may define methods that are invoked after a transfer changes state, for example, to notify an external application on the consumer side after data has been produced (i.e. the transfer moves to the completed state).

// in TransferListenerExtension.java
    @Override
    public void initialize(ServiceExtensionContext context) {
        // ...
        var transferProcessObservable = context.getService(TransferProcessObservable.class);
        transferProcessObservable.registerListener(new MarkerFileCreator(monitor));
    }

public class MarkerFileCreator implements TransferProcessListener {

    /**
     * Callback invoked by the EDC framework when a transfer has completed.
     *
     * @param process
     */
    @Override
    public void completed(final TransferProcess process) {
        // ...
    }
}

Perform a file transfer

Let's rebuild and run them both:

./gradlew samples:04.1-file-transfer-listener:consumer:build
java -Dedc.fs.config=samples/04.1-file-transfer-listener/consumer/config.properties -jar samples/04.1-file-transfer-listener/consumer/build/libs/consumer.jar
# in another terminal window:
./gradlew samples:04.0-file-transfer:provider:build
java -Dedc.fs.config=samples/04.0-file-transfer/provider/config.properties -jar samples/04.0-file-transfer/provider/build/libs/provider.jar

Assuming you didn't change the config files, the consumer will expose management api on port 9192 and the custom api endpoints on port 9191 and the provider will listen on port 8181. Open another terminal window (or any REST client of your choice) and execute the following REST requests like in the previous sample:

curl -X POST -H "Content-Type: application/json" -H "X-Api-Key: password" -d @samples/04.0-file-transfer/contractoffer.json "http://localhost:9192/api/v1/management/contractnegotiations"
curl -X GET -H 'X-Api-Key: password' "http://localhost:9192/api/v1/management/contractnegotiations/{UUID}"
curl -X POST -H "Content-Type: application/json" -H "X-Api-Key: password" -d @samples/04.0-file-transfer/filetransfer.json "http://localhost:9192/api/v1/management/transferprocess"

Replace {UUID} in the second request with the UUID received as the response to the first request!

In samples/04.0-file-transfer/filetransfer.json: Copy the contract agreement's ID from the second response, substitute it for {agreement ID} in the last request JSON body and adjust the dataDestination.properties.path to match your local dev machine!

• curl will return the ID of the transfer process on the consumer connector.

The consumer should spew out logs similar to:

DEBUG 2022-04-14T16:23:13.4042547 Starting transfer for asset test-document
DEBUG 2022-04-14T16:23:13.4072776 Transfer process initialised 6804ed96-298e-4992-b72d-2366d97cf7a6
DEBUG 2022-04-14T16:23:13.8801678 TransferProcessManager: Sending process 6804ed96-298e-4992-b72d-2366d97cf7a6 request to http://localhost:8282/api/v1/ids/data
DEBUG 2022-04-14T16:23:13.9341802 TransferProcessManager: Process 6804ed96-298e-4992-b72d-2366d97cf7a6 is now REQUESTED
DEBUG 2022-04-14T16:23:18.9048494 Process 6804ed96-298e-4992-b72d-2366d97cf7a6 is now IN_PROGRESS
DEBUG 2022-04-14T16:23:18.9048494 Process 6804ed96-298e-4992-b72d-2366d97cf7a6 is now COMPLETED
INFO 2022-04-14T16:23:18.9048494 Transfer Listener successfully wrote file C:\Users\pechande\dev\coding\EDC\marker.txt

Then check /path/on/yourmachine, which should now contain a file named marker.txt in addition to the file defined in dataDestination.properties.path in samples/04.0-file-transfer/filetransfer.json.

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