Schritt 6: Den Revisionsverlauf für ein Dokument anzeigen

Nach dem Bearbeiten der Zulassungsdaten für ein Fahrzeug im vorherigen Schritt können Sie den Verlauf aller registrierten Eigentümer und alle anderen aktualisierten Felder abfragen. In diesem Schritt führen Sie eine Abfrage des Revisionsverlaufs eines Dokuments in der VehicleRegistration-Tabelle in Ihrem vehicle-registration-Ledger durch.

So zeigen Sie den Revisionsverlauf an

1. Überprüfen Sie das folgende Programm (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.");
       }
   }

   Anmerkung

   • Sie können den Revisionsverlauf eines Dokuments anzeigen, indem Sie die integrierte Verlaufsfunktion in der folgenden Syntax abfragen.

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

   • Die Start - und Endzeit sind beide optional. Es handelt sich um Amazon Ion-Literalwerte, die mit Backticks (`...`) gekennzeichnet werden können. Weitere Informationen hierzu finden Sie unter Ion mit PartiQL in Amazon QLDB abfragen.

   • Es hat sich bewährt, eine Verlaufsabfrage sowohl mit einem Datumsbereich (Start- und Endzeit) als auch mit einer Dokument-ID (metadata.id) zu qualifizieren. QLDB verarbeitetSELECT Abfragen in Transaktionen, für die ein Transaktions-Timeout-Limit gilt.

     Der QLDB-Verlauf wird anhand der Dokument-ID indexiert, und Sie können derzeit keine zusätzlichen Verlaufsindizes erstellen. Verlaufsabfragen, die eine Start- und Endzeit enthalten, profitieren von der Qualifizierung des Datumsbereichs.

2. Kompilieren Sie dasQueryHistory.java Programm und führen Sie es aus, um den Revisionsverlauf desVehicleRegistration Dokuments mit VIN abzufragen1N4AL11D75C109151.

Fahren Sie zum kryptografischen Überprüfen einer Dokumentrevision im vehicle-registration-Ledger mit Schritt 7: Verifizieren Sie ein Dokument in einem Ledger fort.