Passaggio 6: visualizzare la cronologia delle revisioni di un documento - Database Amazon Quantum Ledger (Amazon QLDB)

Le traduzioni sono generate tramite traduzione automatica. In caso di conflitto tra il contenuto di una traduzione e la versione originale in Inglese, quest'ultima prevarrà.

Passaggio 6: visualizzare la cronologia delle revisioni di un documento

Dopo aver modificato i dati di registrazione di un veicolo nel passaggio precedente, è possibile interrogare la cronologia di tutti i proprietari registrati e qualsiasi altro campo aggiornato. In questo passaggio, è necessario interrogare la cronologia delle revisioni di un documento nellaVehicleRegistration tabella delvehicle-registration libro contabile.

Per visualizzare la cronologia delle revisioni

  1. Esamina il seguente programma (QueryHistory.java).

    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.time.Instant;
import java.time.temporal.ChronoUnit;

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.SampleData;
import software.amazon.qldb.tutorial.model.VehicleRegistration;

/**
 * Query a table's history for a particular set of documents.
 *
 * 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 QueryHistory {
    public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
    private static final int THREE_MONTHS = 90;

    private QueryHistory() { }

    /**
     * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              VIN to find previous primary owners for.
     * @param query
     *              The query to find previous primary owners.
     * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
     */
    public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
        try {
            final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);

            log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
            final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(docId));
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
        final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                           + "FROM history(VehicleRegistration, `%s`) "
                                           + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
        ConnectToLedger.getDriver().execute(txn -> {
            final String vin = SampleData.VEHICLES.get(0).getVin();
            previousPrimaryOwners(txn, vin, query);
        });
        log.info("Successfully queried history.");
    }
}
    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.IonValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.qldb.QldbSession;
import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.SampleData;
import software.amazon.qldb.tutorial.model.VehicleRegistration;

import java.io.IOException;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Collections;
import java.util.List;

/**
 * Query a table's history for a particular set of documents.
 *
 * 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 QueryHistory {
    public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
    private static final int THREE_MONTHS = 90;

    private QueryHistory() { }

    /**
     * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              VIN to find previous primary owners for.
     * @param query
     *              The query to find previous primary owners.
     * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
     */
    public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
        try {
            final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(docId));
            log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
            final Result result = txn.execute(query, parameters);
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
        final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                           + "FROM history(VehicleRegistration, `%s`) "
                                           + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
        ConnectToLedger.getDriver().execute(txn -> {
            final String vin = SampleData.VEHICLES.get(0).getVin();
            previousPrimaryOwners(txn, vin, query);
        }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
        log.info("Successfully queried history.");
    }
}
    Nota

    • È possibile visualizzare la cronologia delle revisioni di un documento interrogando la sintassi integrataFunzione di cronologia nella seguente sintassi.

      SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
[ WHERE h.metadata.id = 'id' ]

    • L'ora di inizio e l'ora di fine sono entrambe opzionali. Sono valori letterali di Amazon Ion che possono essere indicati con delle barrette inverse (`...`). Per ulteriori informazioni, consulta Interrogazione di Ion con PartiQL in Amazon QLDB.

    • Come procedura consigliata, qualifica un'interrogazione cronologica con un intervallo di date (ora di inizio e ora di fine) e un ID del documento (metadata.id). QLDB elabora leSELECT interrogazioni nelle transazioni, che sono soggette a un limite di timeout delle transazioni.

      La cronologia QLDB è indicizzata in base all'ID del documento e al momento non è possibile creare indici di cronologia aggiuntivi. Le interrogazioni cronologiche che includono un'ora di inizio e un'ora di fine ottengono il vantaggio della qualificazione dell'intervallo di date.

  2. Compila ed esegui ilQueryHistory.java programma per interrogare la cronologia delle revisioni delVehicleRegistration documento con VIN1N4AL11D75C109151.

Per verificare crittograficamente una revisione del documento nelvehicle-registration libro mastro, procedere aFase 7: Verificare un documento in un libro mastro.