Develop Pulsar Functions in Java

This section introduces how to develop and pacakge Java Pulsar functions to use on StreamNative cloud.

Develop

StreamNative supports all features for the Java functions, please refer to: Develop Functions to learn how to develop a Java Function.

Package

Please refer to: Pacakge Java Functions

Deploy

After creating a cluster, set up your environment and develop&package your function, you can use the pulsarctl, pulsar-admin command, the REST API, or terraform to deploy a Pulsar function to your cluster.

You can create a java Pulsar function by using a local JAR/NAR package or an uploaded Pulsar functions package(recommend).

(Optional) Upload your function file to Pulsar

It's recommend to upload your function file to Pulsar before you create a function. Since you can add a version suffix to the package.

You need to set the context for Pulsarctl first:

# create a context
pulsarctl context set ${context-name}  \
--admin-service-url ${admin-service-url} \
--issuer-endpoint ${issuerUrl} \
--audience urn:sn:pulsar:${orgName}:${instanceName} \
--key-file ${privateKey}

# activate oauth2
pulsarctl oauth2 activate

Note

Replace the placeholder variables with the actual values that you can get when setting up client tools.

context-name: any name you want
admin-service-url: the HTTP service URL of your Pulsar cluster.
privateKey: the path to the downloaded OAuth2 key file.
issuerUrl: the URL of the OAuth2 issuer.
audience: the Uniform Resource Name (URN), which is a combination of the urn:sn:pulsar, your organization name, and your Pulsar instance name.
- ${orgName}: the name of your organization.
- ${instanceName}: the name of your instance.

Upload packages

pulsarctl packages upload function://public/default/[email protected] \
--path exclamation-1.0-SNAPSHOT.jar \
--description "exclamation function" \
--properties fileName=exclamation-1.0-SNAPSHOT.jar

You should see the following output:

The package 'function://public/default/[email protected]' uploaded from path 'examples/api-examples.jar' successfully

Create

You need to package your Java function as a .jar or .nar file (and upload it to Pulsar) first.

pulsarctl functions create \
--tenant public \
--namespace default \
--name function1 \
--inputs persistent://public/default/test-java-input \
--output persistent://public/default/test-java-output \
--classname org.apache.pulsar.functions.api.examples.ExclamationFunction \
--jar function://public/default/[email protected]

You should see something like this:

Created function1 successfully

For details about Pulsar function configurations, see Pulsar function configurations.

What’s next?

Learn how to develop Python functions.
Learn how to develop Golang functions.
Learn how to develop NodeJs functions.
Learn how to develop WASM functions.
Learn how to manage functions.
Learn how to monitor functions.
Reference common configurations.