NullPointerException when using custom adapter after deploying extension

[MichaelKoch11]

I created a new adapter and wanted to deploy it as a custom extension.

Steps I followed:

1. Created the adapter extension.
2. Built the Docker image.
3. Deployed the extension in Kubernetes.
4. Installed the extension in StreamPipes.
5. Tried to use the adapter in the UI.

When opening/using the adapter in the UI, I get the following error in the backend logs:

servlet.service() for servlet [dispatcherServlet] in context with path [/streampipes-backend] threw exception [Request processing failed: java.lang.NullPointerException: Cannot invoke "java.util.List.stream()" because the return value of "org.apache.streampipes.model.extensions.svcdiscovery.SpServiceRegistration.getSupportedScriptLanguages()" is null] with root cause
java.lang.NullPointerException: Cannot invoke "java.util.List.stream()" because the return value of "org.apache.streampipes.model.extensions.svcdiscovery.SpServiceRegistration.getSupportedScriptLanguages()" is null
	at org.apache.streampipes.rest.impl.connect.TransformationScriptLanguageResource.getAll(TransformationScriptLanguageResource.java:63)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(Unknown Source)
	at java.base/java.lang.reflect.Method.invoke(Unknown Source)

Environment:

• Extension SDK version: 0.98
• StreamPipes version: 0.99.0-SNAPSHOT
• Deployment: Kubernetes

Could this be caused by an incompatibility between the SDK version and the StreamPipes version, or is this a bug?

Thanks!

[dominikriemer]

Hi @MichaelKoch11 i think it's both :-)

In general it is good to have the SDK version match the used StreamPipes version. For a SNAPSHOT version you can add the ASF Maven repo to your pom file:

<repository>
            <id>apache.snapshots</id>
            <name>Apache Snapshot Repository</name>
            <url>https://repository.apache.org/snapshots</url>
            <snapshots>
                <enabled>true</enabled>
                <updatePolicy>always</updatePolicy>
            </snapshots>
            <releases>
                <enabled>false</enabled>
            </releases>
</repository>
```

But on the other hand the core should be backwards compatible so I'll create an issue to filter the extension service for supported script languages. But if you develop a new adapter it makes sense to switch to the new version so that you benefit from the new transformation script feature.

[MichaelKoch11]

Thanks, that helps a lot.