Writing a custom connector

Camunda 7 Topics Discussion & Questions
1

Good time of the day, Community.

I’ve just started the path of learning Camunda, and have a question, for which I’m struggling to find any actual information - the Connectors!

I’m running the basic embedded Camunda as part of Spring Boot app. My current goal is to write a custom Connector by a simple “extend” from the http-connector.

I believe I got the right set of dependencies,

        <dependency>
            <groupId>org.camunda.connect</groupId>
            <artifactId>camunda-connect-core</artifactId>
        </dependency>

        <dependency>
            <groupId>org.camunda.bpm</groupId>
            <artifactId>camunda-engine-plugin-spin</artifactId>
        </dependency>

        <dependency>
            <groupId>org.camunda.spin</groupId>
            <artifactId>camunda-spin-dataformat-all</artifactId>
        </dependency>

        <dependency>
            <groupId>org.camunda.bpm</groupId>
            <artifactId>camunda-engine-plugin-connect</artifactId>
        </dependency>

        <dependency>
            <groupId>org.camunda.connect</groupId>
            <artifactId>camunda-connect-connectors-all</artifactId>
        </dependency>

And I’m basically doing the

package com.example.workflow.connector.v2;

import org.camunda.connect.httpclient.HttpConnector;
import org.camunda.connect.httpclient.HttpConnectorProvider;
import org.camunda.connect.httpclient.impl.HttpConnectorProviderImpl;
import org.camunda.connect.spi.ConnectorProvider;

public class OmnissiahConnectorProvider extends HttpConnectorProviderImpl implements ConnectorProvider {

    @Override
    public String getConnectorId() {
        System.out.println("+++++++++++++++++++++++++++++++++++++++++++");
        return "omissiah-connector";
    }

    @Override
    public HttpConnector createConnectorInstance() {
        return new OmnissiahHttpConnector();
    }
}

At this stage I believe I’m passing the initial validation of the bpmn, but when it comes to action, I get an error, stating that no connector by the name “omnissiah-connector” exists.

Currently it’s a simple “extends”, but the idea is to have some predefined stuff (like URL) being kept on the side of the connector.

Would be grateful for some advice.

2

Hi @Draakzward and welcome to the community,

The embedded engine for Spring boot uses Spring as an injecion framework.
Have you tried adding the @Component annotation to your class? This way, Spring Boot will handle the injection.
Please let me know if this works.

3

Hi,

Thank you for your reply.

Sadly, it didn’t help.

package com.example.workflow.connector.v2;

import org.camunda.connect.httpclient.HttpConnector;
import org.camunda.connect.httpclient.HttpConnectorProvider;
import org.camunda.connect.httpclient.impl.HttpConnectorProviderImpl;
import org.camunda.connect.spi.ConnectorProvider;
import org.springframework.stereotype.Component;

@Component
public class OmnissiahConnectorProvider extends HttpConnectorProviderImpl implements ConnectorProvider {

Still get the

An error happened while submitting the task form : No connector found for connector id 'omnissiah-connector'

Maybe I’m missing something in the SpringBootApp class?

import org.camunda.bpm.spring.boot.starter.annotation.EnableProcessApplication;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
//@EnableProcessApplication
public class Application {

  public static void main(String... args) {
    SpringApplication.run(Application.class, args);
  }

}
4

Hi,

Sorry, for sending you down the wrong way.
I tried it myself: You do not need the @Component annotation.
However, make sure that you follow all steps explained here.
Especially, add a file META-INF/services/org.camunda.connect.spi.ConnectorProvider that lists your custom connector. The content of my file looks like this:

io.camunda.forum.CustomConnectorProviderImpl

And the referenced CustomConnectorProviderImpl looks like this:

package io.camunda.forum;

import org.camunda.connect.httpclient.HttpConnector;
import org.camunda.connect.httpclient.impl.HttpConnectorImpl;
import org.camunda.connect.httpclient.impl.HttpConnectorProviderImpl;

public class CustomConnectorProviderImpl extends HttpConnectorProviderImpl {

  @Override
  public String getConnectorId() {
    return "custom-connector";
  }

  @Override
  public HttpConnector createConnectorInstance() {
    return new HttpConnectorImpl();
  }
}

I hope this helps.

1 Like
5

I did see this step, but was really hoping that since it’s a spring integration and etc. I wouldn’t be forced to do manual META-INF and everything related.

Thanks, will give it a try.

6

A step closer, but still something’s missing.

I did see the console “+++++++” printout, which I put into getConnectorId during Spring’s initialization. But still a ENGINE-REST-HTTP500 org.camunda.connect.ConnectorException: No connector found for connector id 'omnissiah-connector'.

Strangely enough I see:
2023-01-11 11:52:23.516 INFO 12574 --- [ main] org.camunda.bpm.connect : CNCT-01004 Discovered provider for connector id 'omissiah-connector' and class 'com.example.workflow.connector.v2.OmnissiahHttpConnector': 'com.example.workflow.connector.v2.OmnissiahConnectorProvider'

Making a new instance (or re-copying the connector name in hopes of a typo) helped.

Thank you for your help :slight_smile:

7

There is a typo:
Your implementation spells omissiah-connector your task is configured to search for omnissiah-connector (with an N)

1 Like
8

It wouldn’t be a fun day without having a typo and looking in a completely different direction :smile:

Thank you.

1 Like