Solace Sink Connector for Confluent Platform

The Kafka Connect Solace Sink connector is used to move messages from Apache Kafka® to a Solace PubSub+ cluster.


If you are required to use the Java Naming and Directory Interface™ (JNDI) to connect to Solace, there is a general JMS Sink Connector available that uses a JNDI-based mechanism to connect to the JMS broker.


The following are required to run the Kafka Connect Solace Sink Connector:

  • Kafka Broker: Confluent Platform 3.3.0 or above, or Kafka 0.11.0 or above
  • Connect: Confluent Platform 4.1.0 or above, or Kafka 1.1.0 or above (requires header support in Connect)
  • Solace cluster with JMS 1.1 support
  • com.solacesystems:sol-jms Client Library (See Installing the Solace JMS Client Library)
  • Java 1.8

Install the Solace Sink Connector

You can install this connector by using the Confluent Hub client (recommended) or you can manually download the ZIP file.

Install the connector using Confluent Hub

Confluent Hub Client must be installed. This is installed by default with Confluent Enterprise.

Navigate to your Confluent Platform installation directory and run the following command to install the latest (latest) connector version. The connector must be installed on every machine where Connect will run.

confluent-hub install confluentinc/kafka-connect-solace-sink:latest

You can install a specific version by replacing latest with a version number. For example:

confluent-hub install confluentinc/kafka-connect-solace-sink:1.0.0-preview

Install Connector Manually

Download and extract the ZIP file for your connector and then follow the manual connector installation instructions.


You can use this connector for a 30-day trial period without a license key.

After 30 days, this connector is available under a Confluent enterprise license. Confluent issues enterprise license keys to subscribers, along with providing enterprise-level support for Confluent Platform and your connectors. If you are a subscriber, please contact Confluent Support at for more information.

See Confluent Platform license for license properties and License topic configuration for information about the license topic.

Solace Client Library

The Kafka Connect Solace connector does not come with the Solace JMS client library.

If you are running a multi-node Connect cluster, the Solace connector and Solace JMS client JAR must be installed on every Connect worker in the cluster. See below for details.

Installing the Solace JMS Client Library

This connector relies on a provided com.solacesystems:sol-jms client JAR distributed by Solace. The connector will fail to create a connection to Solace if you have not installed the JAR on each Connect worker node.

The installation steps are:

  1. Download the Solace JMS API. Additional versions are available on Maven.
  2. Unzip the download and copy only the lib/sol-jms-{version}.jar file into the share/java/kafka-connect-solace-sink directory of your Confluent Platform installation on each worker node. If downloading the library from Maven, you do not need to unzip anything as the jar file is the only artifact downloaded.
  3. Restart all of the Connect worker nodes.


The share/java/kafka-connect-solace-sink directory mentioned above is for Confluent Platform. If you are using a different installation, find the location of the Confluent Solace sink connector JAR files and place the sol-jms JAR file into the same directory.

JMS Message Formats

The format of outgoing JMS Message values is configured with the jms.message.format property, using one of the following options:

string (default)

When using the string Message Format, record values are run through Values.convertToString(...) from the Connect Data package and produced as a JMS TextMessage.

Primitive values are converted to their String equivalent and structured objects are transformed to a sensible string representation that is similar to the JSON representation, with the exception of simple string values (not in objects or arrays) which are unquoted.


Kafka Connect Transformations can be used with the configured jms.message.format to transform the record value to the desired string representation before the connector processes each record.


Record values are serialized without the Avro schema information and produced as a JMS BytesMessage. JMS consumers must have the schema to deserialize the data.


The connector attempts to infer the Avro schema for records that have no schema. If the connector cannot infer the schema, the task is killed. If you are processing data without a schema, consider using one of the other jms.message.format configurations.


Record values are converted to a UTF-8 encoded JSON representation and produced as a JMS TextMessage.


Record values are passed along in bytes form without any conversion.


Record values must be converted to bytes form before the connector processes them. Configure the value.converter property to org.apache.kafka.connect.converters.ByteArrayConverter to ensure that record values arrive in byte format.

Forwarding Kafka Properties to JMS

The connector can be configured to forward various values from the Kafka record to the JMS Message.

  • Enable jms.forward.kafka.key to convert the record’s key to a String and forward it as the JMSCorrelationID.
  • Enable jms.forward.kafka.metadata to forward the record’s topic, partition, and offset on JMS Message properties.
    • Kafka topic is applied to the message as a String property named KAFKA_TOPIC.
    • Partition is applied to the message as an Int property named KAFKA_PARTITION.
    • Offset is applied to the message as a Long property named KAFKA_OFFSET.
  • Enable jms.forward.kafka.headers to add each header from the SinkRecord to the JMS Message as a String property.


The connector converts the record key and headers to a sensible string representation that is similar to the JSON representation, with the exception of simple string values (not in objects or arrays) which are unquoted. No other conversion is done to the key and headers before forwarding them on the JMS Message. If another format is needed, out-of-the-box or custom Kafka Connect Transformations can be used with the connector to transform the record keys and/or headers to the desired string representation before the JMS sink connector processes each record.

Quick Start

This quick start uses the Solace Sink Connector to consume records from Kafka and send them to an Solace PubSub+ Standard broker.

  1. Start a Solace PubSub+ Standard docker container.

    docker run -d --name "solace" --hostname "solace" \
      -p 8080:8080 -p 55555:55555 -p 5550:5550 \
      --shm-size=1000000000 \
      --tmpfs /dev/shm \
      --ulimit nofile=2448:38048 \
      -e username_admin_globalaccesslevel=admin \
      -e username_admin_password=admin \
      -e system_scaling_maxconnectioncount=100 \
  2. Install the connector through the Confluent Hub Client.

    # run from your CP installation directory
    confluent-hub install confluentinc/kafka-connect-solace-sink:latest
  3. Install the Solace JMS Client Library.

  4. Start the Confluent Platform.


    The command syntax for the Confluent CLI development commands changed in 5.3.0. These commands have been moved to confluent local. For example, the syntax for confluent start is now confluent local start. For more information, see confluent local.

    confluent local start
  5. Produce test data to the sink-messages topic in Kafka.

    seq 10 | confluent local produce sink-messages
  6. Create a solace-sink.json file with the following contents:

      "name": "SolaceSinkConnector",
      "config": {
        "connector.class": "io.confluent.connect.jms.SolaceSinkConnector",
        "tasks.max": "1",
        "topics": "sink-messages",
        "": "smf://localhost:55555",
        "solace.username": "admin",
        "solace.password": "admin",
        "solace.dynamic.durables": "true",
        "jms.destination.type": "queue",
        "": "connector-quickstart",
        "key.converter": "",
        "value.converter": "",
        "confluent.topic.bootstrap.servers": "localhost:9092",
        "confluent.topic.replication.factor": "1"
  7. Load the Solace Sink Connector.


    You must include a double dash (--) between the topic name and your flag. For more information, see this post.

    confluent local load solace -- -d solace-sink.json
  8. Confirm that the connector is in a RUNNING state.

    confluent local status solace
  9. Navigate to the Solace UI to confirm the messages were delivered to the connector-quickstart queue in the default Message VPN.


    The default credentials for the Solace Admin UI are admin/admin

Additional Documentation