Use Apache Kafka with C#

There are many Apache Kafka clients for C#, a list of some recommended options to use Kafka with C# can be found here. In this example, we’ll be using Confluent’s Kafka .NET client.

Dependencies

Add the Confluent.Kafka package to your application. This package is available via NuGet. You can install Confluent.Kafka from within Visual Studio by searching for Confluent.Kafka in the NuGet UI, or by running this command in the Package Manager Console:

Install-Package Confluent.Kafka

Alternatively, if using the dotnet CLI, run this command:

dotnet add package Confluent.Kafka

Using client ⇆ broker encryption (SSL)

If you have chosen to enable client ⇆ broker encryption on your Apache Kafka cluster, see here for information on the certificates required to establish an SSL connection to your Kafka cluster.

Producing Messages

Messages are produced to Kafka using a  Producer Builder. In this example, we provide only the required properties for the producer. See here for the full list of configuration options.

Make the necessary imports:

Establish the configuration for the Producer:

Ensure the IP addresses, cluster certificate location, and password are filled in and correct. If your Kafka cluster does not have client ⇆ broker encryption enabled your configuration options should instead look like this:

Note: To connect to your Kafka cluster over the private network, use port 9093 instead of 9092.

Now that we have setup the configuration Dictionary, we can create a Producer object:

Once we have a Producer object we can use it to send a message to Kafka:

Note: we move the producer declaration into a using block here so it will be automatically closed cleanly once we’re finished with it.

Consuming Messages

Messages from Kafka are consumed using a Consumer object. In this example, we provide only the required properties for the consumer. See here for the full list of configuration options.

Again, remember to make the necessary imports:

Establish the Consumer configuration:

Ensure the IP addresses, cluster certificate location, and password are filled in and correct. If your Kafka cluster does not have client ⇆ broker encryption enabled your configuration options should instead look like this:

Note: To connect to your Kafka cluster over the private network, use port 9093 instead of 9092.

Now that we have the configuration Dictionary we can create a Consumer object:

Before we can consume messages, we need to subscribe to the topics we wish to receive messages from:

Combined with a loop, we can continually consume and output messages from Kafka as they are produced:

Note: we move the consumer declaration into a using block here so it will be automatically closed cleanly once we’re finished with it.

Putting Them Together

Now that we have a consumer and producer setup, it’s time to combine them.

Start the consumer

Start the consumer before starting the producer because by default consumers only consume messages that were produced after the consumer started.

Start the producer

Now that the consumer is set up and ready to consume messages, you can now start your producer.

If the consumer and producer are setup correctly the consumer should output the message sent by the producer shortly after it was produced.