Couchbase

Alpakka Couchbase allows you to read and write to Couchbase. You can query a bucket from CouchbaseSource using N1QL queries or reading by document ID. Couchbase connector uses Couchbase Java SDK version 2.7.23 behind the scenes.

The Couchbase connector supports all document formats which are supported by the SDK. All those formats use the Document<T>Document[T] interface and this is the level of abstraction that this connector is using.

Artifacts

The Akka dependencies are available from Akka’s library repository. To access them there, you need to configure the URL for this repository.

sbt

resolvers += "Akka library repository".at("https://repo.akka.io/maven")

Maven

<project>
  ...
  <repositories>
    <repository>
      <id>akka-repository</id>
      <name>Akka library repository</name>
      <url>https://repo.akka.io/maven</url>
    </repository>
  </repositories>
</project>

Gradle

repositories {
    mavenCentral()
    maven {
        url "https://repo.akka.io/maven"
    }
}

Additionally, add the dependencies as below.

sbt

val AkkaVersion = "2.10.0"
libraryDependencies ++= Seq(
  "com.lightbend.akka" %% "akka-stream-alpakka-couchbase" % "9.0.0",
  "com.typesafe.akka" %% "akka-stream" % AkkaVersion
)

Maven

<properties>
  <akka.version>2.10.0</akka.version>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencies>
  <dependency>
    <groupId>com.lightbend.akka</groupId>
    <artifactId>akka-stream-alpakka-couchbase_${scala.binary.version}</artifactId>
    <version>9.0.0</version>
  </dependency>
  <dependency>
    <groupId>com.typesafe.akka</groupId>
    <artifactId>akka-stream_${scala.binary.version}</artifactId>
    <version>${akka.version}</version>
  </dependency>
</dependencies>

Gradle

def versions = [
  AkkaVersion: "2.10.0",
  ScalaBinary: "2.13"
]
dependencies {
  implementation "com.lightbend.akka:akka-stream-alpakka-couchbase_${versions.ScalaBinary}:9.0.0"
  implementation "com.typesafe.akka:akka-stream_${versions.ScalaBinary}:${versions.AkkaVersion}"
}

The table below shows direct dependencies of this module and the second tab shows all libraries it depends on transitively.

Direct dependencies

Organization	Artifact	Version
com.couchbase.client	java-client	2.7.23
com.typesafe.akka	akka-pki_2.13	2.10.0
com.typesafe.akka	akka-stream_2.13	2.10.0
io.reactivex	rxjava-reactive-streams	1.2.1
org.scala-lang	scala-library	2.13.12

Dependency tree

com.couchbase.client    java-client    2.7.23    The Apache Software License, Version 2.0
    com.couchbase.client    core-io    1.7.23    The Apache Software License, Version 2.0
        io.opentracing    opentracing-api    0.31.0
        io.reactivex    rxjava    1.3.8    The Apache Software License, Version 2.0
com.typesafe.akka    akka-pki_2.13    2.10.0    BUSL-1.1
    com.hierynomus    asn-one    0.6.0    The Apache License, Version 2.0
    com.typesafe.akka    akka-actor_2.13    2.10.0    BUSL-1.1
        com.typesafe    config    1.4.3    Apache-2.0
        org.scala-lang    scala-library    2.13.12    Apache-2.0
    org.scala-lang    scala-library    2.13.12    Apache-2.0
    org.slf4j    slf4j-api    2.0.16
com.typesafe.akka    akka-stream_2.13    2.10.0    BUSL-1.1
    com.typesafe.akka    akka-actor_2.13    2.10.0    BUSL-1.1
        com.typesafe    config    1.4.3    Apache-2.0
        org.scala-lang    scala-library    2.13.12    Apache-2.0
    com.typesafe.akka    akka-protobuf-v3_2.13    2.10.0    BUSL-1.1
    org.reactivestreams    reactive-streams    1.0.4    MIT-0
    org.scala-lang    scala-library    2.13.12    Apache-2.0
io.reactivex    rxjava-reactive-streams    1.2.1    The Apache Software License, Version 2.0
    io.reactivex    rxjava    1.3.8    The Apache Software License, Version 2.0
    org.reactivestreams    reactive-streams    1.0.4    MIT-0
org.scala-lang    scala-library    2.13.12    Apache-2.0

Overview

Alpakka Couchbase offers both Akka Streams APIs and a more direct API to access Couchbase:

• CouchbaseSessionCouchbaseSession offers a direct API for one-off operations
• CouchbaseSessionRegistryCouchbaseSessionRegistry is an Akka extension to keep track and share CouchbaseSessions within an ActorSystem
• CouchbaseSourceCouchbaseSource, CouchbaseFlowCouchbaseFlow, and CouchbaseSinkCouchbaseSink offer factory methods to create Akka Stream operators

Configuration

All operations use the CouchbaseSession internally. A session is configured with CouchbaseSessionSettingsCouchbaseSessionSettings and a Couchbase bucket name. The Akka Stream factory methods create and access the corresponding session instance behind the scenes.

By default the CouchbaseSessionSettings are read from the alpakka.couchbase.session section from the configuration eg. in your application.conf.

Settings

copysourcealpakka.couchbase {
  session {
    nodes = ["localhost"]
    username = "Administrator"
    password = "password"
  }
}

Using Akka Discovery

To delegate the configuration of Couchbase nodes to any of Akka Discovery’s lookup mechanisms, specify a service name and lookup timeout in the Couchbase section, and pass in DiscoverySupportDiscoverySupport nodes lookup to enrichAsync and configure Akka Discovery accordingly.

The Akka Discovery dependency has to be added explicitly.

Discovery settings (Config discovery)

copysourcealpakka.couchbase {
  session {
    service {
      name = couchbase-service
      lookup-timeout = 1 s
    }
    username = "anotherUser"
    password = "differentPassword"
  }
}

akka.discovery.method = config
akka.discovery.config.services = {
  couchbase-service = {
    endpoints = [
      { host = "akka.io" }
    ]
  }
}

To enable Akka Discovery on the CouchbaseSessionSettings, use DiscoverySupport.nodes() as enrichment function.

Scala

copysourceimport akka.stream.alpakka.couchbase.scaladsl.{CouchbaseSession, DiscoverySupport}
import akka.stream.alpakka.couchbase.{CouchbaseSessionRegistry, CouchbaseSessionSettings}

val registry = CouchbaseSessionRegistry(actorSystem)

val sessionSettings = CouchbaseSessionSettings(actorSystem)
  .withEnrichAsync(DiscoverySupport.nodes())
val sessionFuture: Future[CouchbaseSession] = registry.sessionFor(sessionSettings, bucketName)

Java

copysourceimport akka.stream.alpakka.couchbase.CouchbaseSessionRegistry;
import akka.stream.alpakka.couchbase.CouchbaseSessionSettings;
import akka.stream.alpakka.couchbase.javadsl.DiscoverySupport;
import akka.stream.alpakka.couchbase.javadsl.CouchbaseSession;

CouchbaseSessionRegistry registry = CouchbaseSessionRegistry.get(actorSystem);

CouchbaseSessionSettings sessionSettings =
    CouchbaseSessionSettings.create(actorSystem)
        .withEnrichAsyncCs(DiscoverySupport.getNodes(actorSystem));
CompletionStage<CouchbaseSession> session = registry.getSessionFor(sessionSettings, bucketName);

Reading from Couchbase in Akka Streams

Using statements

To query Couchbase using the statement DSL use CouchbaseSource.fromStatement.

Scala

copysourceimport com.couchbase.client.java.query.Select.select
import com.couchbase.client.java.query.dsl.Expression._

val resultAsFuture: Future[Seq[JsonObject]] =
  CouchbaseSource
    .fromStatement(sessionSettings, select("*").from(i(queryBucketName)).limit(10), bucketName)
    .runWith(Sink.seq)

Java

copysourceimport static com.couchbase.client.java.query.Select.select;
import static com.couchbase.client.java.query.dsl.Expression.*;

CompletionStage<List<JsonObject>> resultCompletionStage =
    CouchbaseSource.fromStatement(
            sessionSettings, select("*").from(i(queryBucketName)).limit(10), bucketName)
        .runWith(Sink.seq(), actorSystem);

Using N1QL queries

To query Couchbase using the “N1QL” queries use CouchbaseSource.fromN1qlQuery.

Scala

copysourceimport com.couchbase.client.java.query.{N1qlParams, N1qlQuery}

val params = N1qlParams.build.adhoc(false)
val query = N1qlQuery.simple(s"select count(*) from $queryBucketName", params)

val resultAsFuture: Future[Seq[JsonObject]] =
  CouchbaseSource
    .fromN1qlQuery(sessionSettings, query, bucketName)
    .runWith(Sink.seq)

Java

copysourceimport com.couchbase.client.java.query.N1qlParams;
import com.couchbase.client.java.query.N1qlQuery;

N1qlParams params = N1qlParams.build().adhoc(false);
SimpleN1qlQuery query = N1qlQuery.simple("select count(*) from " + queryBucketName, params);

CompletionStage<JsonObject> resultCompletionStage =
    CouchbaseSource.fromN1qlQuery(sessionSettings, query, bucketName)
        .runWith(Sink.head(), actorSystem);

Get by ID

CouchbaseFlow.fromId methods allow to read documents specified by the document ID in the Akka Stream.

Scala

copysourceval ids = immutable.Seq("First", "Second", "Third", "Fourth")

val futureResult: Future[immutable.Seq[JsonDocument]] =
  Source(ids)
    .via(
      CouchbaseFlow.fromId(
        sessionSettings,
        bucketName
      )
    )
    .runWith(Sink.seq)

Java

copysourceList<String> ids = Arrays.asList("First", "Second", "Third", "Fourth");

CompletionStage<List<JsonDocument>> result =
    Source.from(ids)
        .via(CouchbaseFlow.fromId(sessionSettings, queryBucketName))
        .runWith(Sink.seq(), actorSystem);

Writing to Couchbase in Akka Streams

For each mutation operation we need to create CouchbaseWriteSettingsCouchbaseWriteSettings instance which consists of the following parameters

• Parallelism in access to Couchbase (default 1)
• Couchbase Replication Factor (default ReplicateTo.NONE)
• Couchbase Persistence Level for Write Operation (default PersistTo.NONE)
• 2 seconds operation timeout

These default values are not recommended for production use, as they do not persist to disk for any node.

Scala

copysourceimport akka.stream.alpakka.couchbase.CouchbaseWriteSettings
import com.couchbase.client.java.{PersistTo, ReplicateTo}
val writeSettings = CouchbaseWriteSettings()
  .withParallelism(3)
  .withPersistTo(PersistTo.FOUR)
  .withReplicateTo(ReplicateTo.THREE)
  .withTimeout(5.seconds)

Java

copysourceCouchbaseWriteSettings writeSettings =
    CouchbaseWriteSettings.create()
        .withParallelism(3)
        .withPersistTo(PersistTo.FOUR)
        .withReplicateTo(ReplicateTo.THREE)
        .withTimeout(Duration.ofSeconds(5));

Read more about durability settings in the Couchbase documentation.

Upsert

The CouchbaseFlow and CouchbaseSink offer factories for upserting documents (insert or update) in Couchbase. upsert is used for the most commonly used JsonDocument, and upsertDoc has as type parameter to support any variants of Document[T]Document<T> which may be RawJsonDocument, StringDocument or BinaryDocument.

The upsert and upsertDoc operators fail the stream on any error when writing to Couchbase. To handle failures in-stream use upsertDocWithResult shown below.

Scala

copysourceval obj = TestObject(id = "First", "First")

val writeSettings = CouchbaseWriteSettings()

val jsonDocumentUpsert: Future[Done] =
  Source
    .single(obj)
    .map(toJsonDocument)
    .via(
      CouchbaseFlow.upsert(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.ignore)

val stringDocumentUpsert: Future[Done] =
  Source
    .single(sampleData)
    .map(toStringDocument)
    .via(
      CouchbaseFlow.upsertDoc(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.ignore)

Java

copysourceCompletionStage<JsonDocument> jsonDocumentUpsert =
    Source.single(obj)
        .map(support::toJsonDocument)
        .via(CouchbaseFlow.upsert(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.head(), actorSystem);

Couchbase writes may fail temporarily for a particular node. If you want to handle such failures without restarting the whole stream, the upsertDocWithResult operator captures failures from Couchbase and emits CouchbaseWriteResult sub-classes CouchbaseWriteSuccess and CouchbaseWriteFailure downstream.

Scala

copysourceimport akka.stream.alpakka.couchbase.{CouchbaseWriteFailure, CouchbaseWriteResult}

val result: Future[immutable.Seq[CouchbaseWriteResult[RawJsonDocument]]] =
  Source(sampleSequence)
    .map(toRawJsonDocument)
    .via(
      CouchbaseFlow.upsertDocWithResult(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.seq)

val failedDocs: immutable.Seq[CouchbaseWriteFailure[RawJsonDocument]] = result.futureValue.collect {
  case res: CouchbaseWriteFailure[RawJsonDocument] => res
}

Java

copysourceimport akka.stream.alpakka.couchbase.CouchbaseWriteFailure;
import akka.stream.alpakka.couchbase.CouchbaseWriteResult;
CompletionStage<List<CouchbaseWriteResult<StringDocument>>> upsertResults =
    Source.from(sampleSequence)
        .map(support::toStringDocument)
        .via(CouchbaseFlow.upsertDocWithResult(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.seq(), actorSystem);

List<CouchbaseWriteResult<StringDocument>> writeResults =
    upsertResults.toCompletableFuture().get(3, TimeUnit.SECONDS);
List<CouchbaseWriteFailure<StringDocument>> failedDocs =
    writeResults.stream()
        .filter(CouchbaseWriteResult::isFailure)
        .map(res -> (CouchbaseWriteFailure<StringDocument>) res)
        .collect(Collectors.toList());

Replace

The CouchbaseFlow and CouchbaseSink offer factories for replacing documents in Couchbase. replace is used for the most commonly used JsonDocument, and replaceDoc has as type parameter to support any variants of Document[T]Document<T> which may be RawJsonDocument, StringDocument or BinaryDocument.

The replace and replaceDoc operators fail the stream on any error when writing to Couchbase. To handle failures in-stream use replaceDocWithResult shown below.

A replace action will fail if the original Document can’t be found in Couchbase with a DocumentDoesNotExistException.

Scala

copysourceval replaceFuture: Future[Done] =
  Source
    .single(obj)
    .map(toJsonDocument)
    .via(
      CouchbaseFlow.replace(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.ignore)

Java

copysourceimport com.couchbase.client.java.error.DocumentDoesNotExistException;
CompletionStage<JsonDocument> jsonDocumentReplace =
    Source.single(obj)
        .map(support::toJsonDocument)
        .via(CouchbaseFlow.replace(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.head(), actorSystem);
CompletionStage<JsonDocument> jsonDocumentReplace =
    Source.single(obj)
        .map(support::toJsonDocument)
        .via(CouchbaseFlow.replace(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.head(), actorSystem);

Couchbase writes may fail temporarily for a particular node. If you want to handle such failures without restarting the whole stream, the replaceDocWithResult operator captures failures from Couchbase and emits CouchbaseWriteResult sub-classes CouchbaseWriteSuccess and CouchbaseWriteFailure downstream.

Scala

copysourceimport akka.stream.alpakka.couchbase.{CouchbaseWriteFailure, CouchbaseWriteResult}

val result: Future[immutable.Seq[CouchbaseWriteResult[RawJsonDocument]]] =
  Source(sampleSequence)
    .map(toRawJsonDocument)
    .via(
      CouchbaseFlow.upsertDocWithResult(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.seq)

val failedDocs: immutable.Seq[CouchbaseWriteFailure[RawJsonDocument]] = result.futureValue.collect {
  case res: CouchbaseWriteFailure[RawJsonDocument] => res
}

Java

copysourceimport akka.stream.alpakka.couchbase.CouchbaseWriteFailure;
import akka.stream.alpakka.couchbase.CouchbaseWriteResult;
CompletionStage<List<CouchbaseWriteResult<StringDocument>>> upsertResults =
    Source.from(sampleSequence)
        .map(support::toStringDocument)
        .via(CouchbaseFlow.upsertDocWithResult(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.seq(), actorSystem);

List<CouchbaseWriteResult<StringDocument>> writeResults =
    upsertResults.toCompletableFuture().get(3, TimeUnit.SECONDS);
List<CouchbaseWriteFailure<StringDocument>> failedDocs =
    writeResults.stream()
        .filter(CouchbaseWriteResult::isFailure)
        .map(res -> (CouchbaseWriteFailure<StringDocument>) res)
        .collect(Collectors.toList());

Delete

The CouchbaseFlow and CouchbaseSink offer factories to delete documents in Couchbase by ID.

Scala

copysourceval deleteFuture: Future[Done] =
  Source
    .single(sampleData.id)
    .via(
      CouchbaseFlow.delete(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.ignore)

Java

copysourceCompletionStage<String> result =
    Source.single(sampleData.id())
        .via(CouchbaseFlow.delete(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.head(), actorSystem);

To handle any delete failures such as non-existent documents in-stream, use the the deleteWithResult operator. It captures failures from Couchbase and emits CouchbaseDeleteResults.

Scala

copysourceval deleteResult: Future[CouchbaseDeleteResult] =
  Source
    .single("non-existent")
    .via(
      CouchbaseFlow.deleteWithResult(
        sessionSettings,
        writeSettings,
        bucketName
      )
    )
    .runWith(Sink.head)

Java

copysourceimport akka.stream.alpakka.couchbase.CouchbaseDeleteResult;
CompletionStage<CouchbaseDeleteResult> result =
    Source.single("non-existent")
        .via(CouchbaseFlow.deleteWithResult(sessionSettings, writeSettings, bucketName))
        .runWith(Sink.head(), actorSystem);

Using CouchbaseSession directly

Access via registry

The CouchbaseSesionRegistry is an Akka extension to manage the life-cycle of Couchbase sessions. All underlying instances are closed upon actor system termination.

When accessing more than one Couchbase cluster, the CouchbaseEnvironment should be shared by setting a single instance for the different CouchbaseSessionSettings.

Scala

copysourceimport akka.stream.alpakka.couchbase.CouchbaseSessionRegistry
import akka.stream.alpakka.couchbase.CouchbaseSessionSettings
import akka.stream.alpakka.couchbase.scaladsl.CouchbaseSession
import com.couchbase.client.java.env.{CouchbaseEnvironment, DefaultCouchbaseEnvironment}

// Akka extension (singleton per actor system)
val registry = CouchbaseSessionRegistry(actorSystem)

// If connecting to more than one Couchbase cluster, the environment should be shared
val environment: CouchbaseEnvironment = DefaultCouchbaseEnvironment.create()
actorSystem.registerOnTermination {
  environment.shutdown()
}

val sessionSettings = CouchbaseSessionSettings(actorSystem)
  .withEnvironment(environment)
val sessionFuture: Future[CouchbaseSession] = registry.sessionFor(sessionSettings, bucketName)

Java

copysourceimport com.couchbase.client.java.env.CouchbaseEnvironment;
import com.couchbase.client.java.env.DefaultCouchbaseEnvironment;
import akka.stream.alpakka.couchbase.CouchbaseSessionRegistry;
import akka.stream.alpakka.couchbase.CouchbaseSessionSettings;
import akka.stream.alpakka.couchbase.javadsl.CouchbaseSession;

CouchbaseSessionRegistry registry = CouchbaseSessionRegistry.get(actorSystem);

// If connecting to more than one Couchbase cluster, the environment should be shared
CouchbaseEnvironment environment = DefaultCouchbaseEnvironment.create();
actorSystem.registerOnTermination(() -> environment.shutdown());

CouchbaseSessionSettings sessionSettings =
    CouchbaseSessionSettings.create(actorSystem).withEnvironment(environment);
CompletionStage<CouchbaseSession> sessionCompletionStage =
    registry.getSessionFor(sessionSettings, bucketName);

Manage session life-cycle

Use CouchbaseSessionSettings to get an instance of CouchbaseSession. These settings may be specified in application.conf and complemented in code. Furthermore a session requires the bucket name and needs an ExecutionContext as the creation is asynchronous.

Scala

copysourceimport akka.stream.alpakka.couchbase.CouchbaseSessionSettings
import akka.stream.alpakka.couchbase.scaladsl.CouchbaseSession

implicit val ec: ExecutionContext = actorSystem.dispatcher
val sessionSettings = CouchbaseSessionSettings(actorSystem)
val sessionFuture: Future[CouchbaseSession] = CouchbaseSession(sessionSettings, bucketName)
actorSystem.registerOnTermination(sessionFuture.flatMap(_.close()))

val documentFuture = sessionFuture.flatMap { session =>
  val id = "myId"
  val documentFuture: Future[Option[JsonDocument]] = session.get(id)
  documentFuture.flatMap {
    case Some(jsonDocument) =>
      Future.successful(jsonDocument)
    case None =>
      Future.failed(new RuntimeException(s"document $id wasn't found"))
  }
}

Java

copysourceimport akka.stream.alpakka.couchbase.CouchbaseSessionSettings;
import akka.stream.alpakka.couchbase.javadsl.CouchbaseSession;

Executor executor = Executors.newSingleThreadExecutor();
CouchbaseSessionSettings sessionSettings = CouchbaseSessionSettings.create(actorSystem);
CompletionStage<CouchbaseSession> sessionCompletionStage =
    CouchbaseSession.create(sessionSettings, bucketName, executor);
actorSystem.registerOnTermination(
    () -> sessionCompletionStage.thenAccept(CouchbaseSession::close));

sessionCompletionStage.thenAccept(
    session -> {
      String id = "myId";
      CompletionStage<Optional<JsonDocument>> documentCompletionStage = session.get(id);
      documentCompletionStage.thenAccept(
          opt -> {
            if (opt.isPresent()) {
              System.out.println(opt.get());
            } else {
              System.out.println("Document " + id + " wasn't found");
            }
          });
    });

Manage bucket life-cycle

For full control a CouchbaseSession may be created from a Couchbase Bucket. See Scalability and Concurrency in the Couchbase documentation for details.

Scala

copysourceimport com.couchbase.client.java.auth.PasswordAuthenticator
import com.couchbase.client.java.{Bucket, CouchbaseCluster}

val cluster: CouchbaseCluster = CouchbaseCluster.create("localhost")
cluster.authenticate(new PasswordAuthenticator("Administrator", "password"))
val bucket: Bucket = cluster.openBucket("akka")
val session: CouchbaseSession = CouchbaseSession(bucket)
actorSystem.registerOnTermination {
  session.close()
}

val id = "myId"
val documentFuture = session.get(id).flatMap {
  case Some(jsonDocument) =>
    Future.successful(jsonDocument)
  case None =>
    Future.failed(new RuntimeException(s"document $id wasn't found"))
}

Java

copysourceimport com.couchbase.client.java.Bucket;
import com.couchbase.client.java.CouchbaseCluster;
import com.couchbase.client.java.auth.PasswordAuthenticator;

CouchbaseCluster cluster = CouchbaseCluster.create("localhost");
cluster.authenticate(new PasswordAuthenticator("Administrator", "password"));
Bucket bucket = cluster.openBucket("akka");
CouchbaseSession session = CouchbaseSession.create(bucket);
actorSystem.registerOnTermination(
    () -> {
      session.close();
      bucket.close();
    });

String id = "First";
CompletionStage<Optional<JsonDocument>> documentCompletionStage = session.get(id);
documentCompletionStage.thenAccept(
    opt -> {
      if (opt.isPresent()) {
        System.out.println(opt.get());
      } else {
        System.out.println("Document " + id + " wasn't found");
      }
    });

To learn about the full range of operations on CouchbaseSession, read the CouchbaseSessionCouchbaseSession API documentation.