I have a remote server installation of the Camunda BPM Platform (installed using the Camunda BPM Platform Helm Chart - https://github.com/camunda-community-hub/camunda-helm/tree/main/charts/camunda-bpm-platform). It is working as expected and, while new to BPM, I have been able to try out some workflows and examples successfully.
I am now trying to connect to it remotely and register for thrown events. I've been following https://docs.camunda.org/manual/7.15/reference/bpmn20/events/signal-events/ however I am stumped as to how I can get a handle to runtimeService. Other than using the REST API is there another way to connect to a remote Camunda service? I've tried using the camunda-bpm-spring-boot-starter-external-task-client but no RuntimeService gets initialized. Perhaps I'm missing some remote-specific configuration but I have not found anything in the documentation so far. Based on https://camunda.com/best-practices/deciding-about-your-stack/ I understand that this should be possible - however, all examples I've found deal with an embedded service. Any help is appreciated!
CAMUNDA offers a Java API and a REST API. In addition there are official or community client libraries, which all rely on the REST API. The Java API is only available to code which gets deployed inside the CAMUNDA JVM.
To interact with the engine from outside the JVM you have to use the REST API. The endpoints are named after the resources, not after the Java API services. Hence you You will not find a RuntimeService endpoint on the REST API, but you will find all the functionality the RuntimeService offers, e.g. start via process-definition.
If you do not want to deploy code in the CAMUNDA JVM, then service integration is done preferably using the external task pattern. If you want to use Java, especially the new Spring Boot Starter for external task clients is fun to work with. If you prefer other languages, check out https://github.com/camunda/awesome-camunda-external-clients.
Unfortunately there currently is no implementation type external for signal events so far. Ootb you can work with signal events for 1:n communication between different BPMN processes on the same environment. If you want to send the signal to an external event bus, then you need to add this functionality to the same JVM as a one-time effort. Here is an example for Azure event bus: https://github.com/camunda-consulting/code/tree/master/snippets/engine-plugin-signal-to-azure-eventhub. The implementation would look very similar for SQS or other alternatives.
If you need to modify the container image to include custom code then you can either just add own jars to e.g. the CAMUNDA RUN Docker image as shown here: https://github.com/rob2universe/bpmrun-add-to-dockerimg or you could build your own image based on the Spring Boot Starter as shown here: https://github.com/rob2universe/camunda-aks