Step 5: Modify documents in a ledger

Important

End of support notice: Existing customers will be able to use Amazon QLDB until end of support on 07/31/2025. For more details, see Migrate an Amazon QLDB Ledger to Amazon Aurora PostgreSQL.

Now that you have data to work with, you can start making changes to documents in the vehicle-registration ledger in Amazon QLDB. In this step, the following code examples demonstrate how to run data manipulation language (DML) statements. These statements update the primary owner of one vehicle and add a secondary owner to another vehicle.

To modify documents

Compile and run the following program (TransferVehicleOwnership.java) to update the primary owner of the vehicle with VIN 1N4AL11D75C109151 in your ledger.

2.x


/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import com.amazon.ion.IonReader;
import com.amazon.ion.IonStruct;
import com.amazon.ion.IonValue;
import com.amazon.ion.system.IonReaderBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.Owner;
import software.amazon.qldb.tutorial.model.Person;
import software.amazon.qldb.tutorial.model.SampleData;

/**
 * Find primary owner for a particular vehicle's VIN.
 * Transfer to another primary owner for a particular vehicle's VIN.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class TransferVehicleOwnership {
    public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);

    private TransferVehicleOwnership() { }

    /**
     * Query a driver's information using the given ID.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param documentId
     *              The unique ID of a document in the Person table.
     * @return a {@link Person} object.
     * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
     */
    public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
        try {
            log.info("Finding person for documentId: {}...", documentId);
            final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";

            Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
            if (result.isEmpty()) {
                throw new IllegalStateException("Unable to find person with ID: " + documentId);
            }

            return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Find the primary owner for the given VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @return a {@link Person} object.
     * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
     */
    public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
        try {
            log.info("Finding primary owner for vehicle with Vin: {}...", vin);
            final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
            Result result = txn.execute(query, parameters);
            final List<IonStruct> documents = ScanTable.toIonStructs(result);
            ScanTable.printDocuments(documents);
            if (documents.isEmpty()) {
                throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
            }

            final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
            final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
            return findPersonFromDocumentId(txn, personId);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Update the primary owner for a vehicle registration with the given documentId.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param documentId
     *              New PersonId for the primary owner.
     * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
     * to convert parameters into {@link IonValue}.
     */
    public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
        try {
            log.info("Updating primary owner for vehicle with Vin: {}...", vin);
            final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";

            final List<IonValue> parameters = new ArrayList<>();
            parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
            parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));

            Result result = txn.execute(query, parameters);
            ScanTable.printDocuments(result);
            if (result.isEmpty()) {
                throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
            } else {
                log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
            }
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String vin = SampleData.VEHICLES.get(0).getVin();
        final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
        final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();

        ConnectToLedger.getDriver().execute(txn -> {
            final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
            if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                // Verify the primary owner.
                throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
            }

            final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
            updateVehicleRegistration(txn, vin, newOwner);
        });
        log.info("Successfully transferred vehicle ownership!");
    }
}

1.x


/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import com.amazon.ion.IonReader;
import com.amazon.ion.IonStruct;
import com.amazon.ion.IonValue;
import com.amazon.ion.system.IonReaderBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.Owner;
import software.amazon.qldb.tutorial.model.Person;
import software.amazon.qldb.tutorial.model.SampleData;

/**
 * Find primary owner for a particular vehicle's VIN.
 * Transfer to another primary owner for a particular vehicle's VIN.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class TransferVehicleOwnership {
    public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);

    private TransferVehicleOwnership() { }

    /**
     * Query a driver's information using the given ID.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param documentId
     *              The unique ID of a document in the Person table.
     * @return a {@link Person} object.
     * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
     */
    public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
        try {
            log.info("Finding person for documentId: {}...", documentId);
            final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";

            Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
            if (result.isEmpty()) {
                throw new IllegalStateException("Unable to find person with ID: " + documentId);
            }

            return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Find the primary owner for the given VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @return a {@link Person} object.
     * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
     */
    public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
        try {
            log.info("Finding primary owner for vehicle with Vin: {}...", vin);
            final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
            Result result = txn.execute(query, parameters);
            final List<IonStruct> documents = ScanTable.toIonStructs(result);
            ScanTable.printDocuments(documents);
            if (documents.isEmpty()) {
                throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
            }

            final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
            final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
            return findPersonFromDocumentId(txn, personId);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Update the primary owner for a vehicle registration with the given documentId.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param documentId
     *              New PersonId for the primary owner.
     * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
     * to convert parameters into {@link IonValue}.
     */
    public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
        try {
            log.info("Updating primary owner for vehicle with Vin: {}...", vin);
            final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";

            final List<IonValue> parameters = new ArrayList<>();
            parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
            parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));

            Result result = txn.execute(query, parameters);
            ScanTable.printDocuments(result);
            if (result.isEmpty()) {
                throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
            } else {
                log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
            }
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String vin = SampleData.VEHICLES.get(0).getVin();
        final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
        final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();

        ConnectToLedger.getDriver().execute(txn -> {
            final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
            if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                // Verify the primary owner.
                throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
            }

            final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
            updateVehicleRegistration(txn, vin, newOwner);
        }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
        log.info("Successfully transferred vehicle ownership!");
    }
}

Compile and run the following program (AddSecondaryOwner.java) to add a secondary owner to the vehicle with VIN KM8SRDHF6EU074761 in your ledger.

2.x


/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.amazon.ion.IonValue;

import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.Owner;
import software.amazon.qldb.tutorial.model.Owners;
import software.amazon.qldb.tutorial.model.Person;
import software.amazon.qldb.tutorial.model.SampleData;

/**
 * Finds and adds secondary owners for a vehicle.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class AddSecondaryOwner {
    public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);

    private AddSecondaryOwner() { }

    /**
     * Check whether a secondary owner has already been registered for the given VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param secondaryOwnerId
     *              The secondary owner to add.
     * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
     * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
     */
    public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                     final String secondaryOwnerId) {
        try {
            log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
            final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
            final Result result = txn.execute(query, parameters);
            final Iterator<IonValue> itr = result.iterator();
            if (!itr.hasNext()) {
                return false;
            }

            final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
            if (null != owners.getSecondaryOwners()) {
                for (Owner owner : owners.getSecondaryOwners()) {
                    if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                        return true;
                    }
                }
            }

            return false;
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Adds a secondary owner for the specified VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param secondaryOwner
     *              The secondary owner to add.
     * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
     */
    public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                               final String secondaryOwner) {
        try {
            log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
            final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = ?" +
                    "INSERT INTO v.Owners.SecondaryOwners VALUE ?");
            final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
            final IonValue vinAsIonValue = Constants.MAPPER.writeValueAsIonValue(vin);
            Result result = txn.execute(query, vinAsIonValue, newOwner);
            log.info("VehicleRegistration Document IDs which had secondary owners added: ");
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String vin = SampleData.VEHICLES.get(1).getVin();
        final String govId = SampleData.PEOPLE.get(0).getGovId();

        ConnectToLedger.getDriver().execute(txn -> {
            final String documentId = Person.getDocumentIdByGovId(txn, govId);
            if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
            } else {
                addSecondaryOwnerForVin(txn, vin, documentId);
            }
        });
        log.info("Secondary owners successfully updated.");
    }
}

1.x


/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.amazon.ion.IonValue;

import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.Owner;
import software.amazon.qldb.tutorial.model.Owners;
import software.amazon.qldb.tutorial.model.Person;
import software.amazon.qldb.tutorial.model.SampleData;

/**
 * Finds and adds secondary owners for a vehicle.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class AddSecondaryOwner {
    public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);

    private AddSecondaryOwner() { }

    /**
     * Check whether a secondary owner has already been registered for the given VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param secondaryOwnerId
     *              The secondary owner to add.
     * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
     * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
     */
    public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                     final String secondaryOwnerId) {
        try {
            log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
            final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
            final Result result = txn.execute(query, parameters);
            final Iterator<IonValue> itr = result.iterator();
            if (!itr.hasNext()) {
                return false;
            }

            final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
            if (null != owners.getSecondaryOwners()) {
                for (Owner owner : owners.getSecondaryOwners()) {
                    if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                        return true;
                    }
                }
            }

            return false;
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    /**
     * Adds a secondary owner for the specified VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              Unique VIN for a vehicle.
     * @param secondaryOwner
     *              The secondary owner to add.
     * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
     */
    public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                               final String secondaryOwner) {
        try {
            log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
            final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = '%s' " +
                    "INSERT INTO v.Owners.SecondaryOwners VALUE ?", vin);
            final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
            Result result = txn.execute(query, newOwner);
            log.info("VehicleRegistration Document IDs which had secondary owners added: ");
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String vin = SampleData.VEHICLES.get(1).getVin();
        final String govId = SampleData.PEOPLE.get(0).getGovId();

        ConnectToLedger.getDriver().execute(txn -> {
            final String documentId = Person.getDocumentIdByGovId(txn, govId);
            if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
            } else {
                addSecondaryOwnerForVin(txn, vin, documentId);
            }
        }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
        log.info("Secondary owners successfully updated.");
    }
}

To review these changes in the vehicle-registration ledger, see Step 6: View the revision history for a document.

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Document Conventions

Step 4: Query the tables

Step 6: View the revision history