Camunda Development

Camunda Development

Decide between out-of-the-box connectors, custom connector templates, custom Java connectors via the Connectors SDK, and job workers before writing any integration code for Camunda 8.8+. This skill is a thin orientation layer — every path it identifies has its own focused build skill.

Cross-References

• camunda-connectors: Use for browsing and applying an existing OOTB connector template
• camunda-connectors-development: Use for building a custom connector (JSON-only template on a protocol connector, or a Java connector via the Connectors SDK; covers both outbound and inbound)
• camunda-job-workers: Use for implementing a job worker in Java, Spring Boot, or TypeScript
• camunda-bpmn: Use for the BPMN element (service task, message event, …) that hosts the connector or worker job
• camunda-process-test: Use for testing the resulting process

Decision matrix

Walk the questions top-down. Stop at the first one whose answer is yes.

1. Does an out-of-the-box (OOTB) connector cover the integration? Search the local catalog with c8ctl element-template search "<keyword>" (see camunda-connectors). If a template matches the target system, use it as-is. Stop.

2. Is the integration a single API call over a common protocol (REST, SOAP, GraphQL, Kafka, RabbitMQ, AWS SQS/SNS, …), and do you want a reusable, modeller-friendly building block? → Path A — JSON-only template on a protocol connector. No Java, no separate runtime. Customise the protocol connector's published template: pre-fill the URL with FEEL, hide method / base URL / auth, expose only the domain-specific properties. See camunda-connectors-development.

3. Is the logic more than a single API call (proprietary protocol, multi-step orchestration with state, non-HTTP I/O, custom inbound trigger) and is the team on Java? → Path B — Custom Java connector via the Connectors SDK. Annotation-driven, auto-generated element template, built-in secrets / intrinsic functions / Camunda Documents. Works for outbound and inbound. See camunda-connectors-development.

4. Otherwise — non-Java stack, or the logic already lives in your application, or you need low-level Zeebe APIs (job streaming, custom activation). → Path C — Job worker. Implement the handler in your app using one of the official SDKs (Java, Spring Boot, TypeScript covered here; other SDKs follow the same pattern). If you also want a modeller UI for the worker, hand-author an element template JSON. See camunda-job-workers.

Comparison: job worker vs. connector (SDK)

The table is the why behind the matrix: connectors trade language reach for reusability and a richer surface; workers trade that surface for language choice and direct Zeebe access.

Worked example — applying the matrix

"Notify Slack when an order is approved. The team is on Node.js."

1. OOTB connector? c8ctl element-template search "slack" returns io.camunda.connectors.Slack.v1. The bot-message operation covers a one-off notification with no custom UI requirement. → Use it. Stop here.

"Submit a job to our internal HTTP pricing API. The team is on Java. We want a reusable connector with only customerId, productSku, and quantity exposed in Modeler."

1. OOTB? No matching template.
2. Single API call over a protocol, Java team, reusable building block? Yes — REST. → Path A. Take the published HTTP REST connector template, pre-fill the URL with a FEEL expression that builds the request URL from customerId, hide the method / base URL / auth fields, expose only the three domain properties. JSON-only; nothing to deploy as a runtime. See camunda-connectors-development.

"Periodically pull invoices from an SFTP server and start a process per file. Team is on Java."

1. OOTB? No SFTP-pull start-event connector that fits.
2. Single API call over a common protocol? No — SFTP, custom poll cadence, inbound trigger.
3. Complex integration, Java team? Yes. → Path B, with the Polling inbound flavour. Build it with the Connectors SDK. See camunda-connectors-development.

"Score a customer record using the team's existing Node.js scoring service."

1. OOTB? No.
2. Single API call over a protocol, Java team? Team is on Node.js — fails on language. (You could still wrap a Java REST template around the scoring service, but the logic already lives in the Node.js app and there is no Java team to maintain a connector.)
3. Java team? No. → Path C, job worker. Wire the existing Node.js service to handle a score-customer job via the TypeScript SDK. See camunda-job-workers.

Mixing in one project

Workers and connectors are a per-task choice, not a per-project one. A single Spring Boot application can host job workers (via the Camunda Spring Boot Starter) and an embedded connector runtime (via spring-boot-starter-camunda-connectors) side by side — the Connectors SDK itself builds on the Spring Boot Starter. Pick the right shape for each integration; you do not need to commit the whole project to one path.

Multi-artifact delivery orchestration (BPMN + workers + DMN + forms)

When a process spans multiple service tasks, user tasks, and business-rule tasks, orchestrate implementation as a structured handoff instead of ad-hoc generation:

1. Build an explicit implementation plan from the BPMN:
   • service task / message event integration points → connector or worker path
   • user tasks with formId → .form deliverables
   • business-rule tasks with decisionId → .dmn deliverables
2. Review and approve that plan before generating artifacts.
3. Implement independent domains in parallel where safe:
   • workers/connectors
   • DMN decisions
   • forms
   • BPMN execution wiring updates
4. Run domain validation loops:
   • BPMN: c8ctl bpmn lint (and compatibility checks as needed)
   • DMN: npx --yes dmnlint (structural) + FEEL/hit-policy test execution (see camunda-dmn)
   • Forms: JSON schema validity — required fields, schemaVersion, component key uniqueness (see camunda-forms)
5. Run a cross-artifact wiring audit before deployment:
   • every non-connector taskDefinition type (typically values without connector-style colons, e.g. check-credit) is implemented by a worker; connector runtime task types (for example io.camunda:slack:1) are resolved by connector templates/runtime, not custom workers
   • every referenced formId exists and matches form id
   • every referenced decisionId exists in deployed DMN resources
6. Deploy only categories that are validation-clean; if a category is intentionally excluded, record that explicitly and keep release status as partial until fixed.

This keeps large Camunda deliveries deterministic, reviewable, and safe to iterate.

Inbound is a connector concern

Inbound triggers — events flowing into a process from an external system — are implemented only via the Connectors SDK. There is no job-worker path for inbound: job workers exclusively handle outbound jobs the engine has already activated.

The SDK supports three inbound flavours, and the choice drives which BPMN element types your element template applies to (message-start event, intermediate catch event, boundary event, …):

• Webhook — the runtime hosts an HTTP listener; the external system calls in.
• Subscription — the runtime opens a long-lived connection to a message broker (Kafka, RabbitMQ, AMQP, …) and consumes events.
• Polling — the runtime polls an external endpoint on a schedule.

If the integration is inbound, paths A and B in the decision matrix are the only options; path C does not apply. See camunda-connectors-development.

Local prerequisites

The decision matrix points at a path; that path needs a working local toolchain. See references/prerequisites.md for the per-workflow overview (which tools each path expects — Node.js, JRE, JDK + Maven, Docker), OS-agnostic verification one-liners, and the cross-cutting gotchas (JAVA_HOME vs PATH, Docker daemon vs CLI, why not to pre-pull camunda/zeebe:latest). Specific minimum versions live in the linked skill for each path — they move with each Camunda release.

References

• prerequisites.md — Local dev environment matrix (JDK / Node.js / Maven / Docker per workflow), verification one-liners, and tooling gotchas.