Inbound Postgres Connector Template

!!! Work in progress !!!

A starting point to build a Start and Intermediate Inbound Postgres Connector. Use the Notify/Listen feature along with database triggers in Postgres to start process instances or catch intermediate events. Feedback and PRs are welcome! In the Connector you'll need to provide the Postgres URL, username, password, channel, the directory to be monitored, and the long polling interval in seconds.

There is one output. It can be accessed from the event object: event.payload

The payload is defined in the trigger function and is limited to a string. JSON formatted trigger output text will be treated as JSON in the output.

An example of JSON formatted text in a trigger notifying a channel in Postgres:

For intermediate catch events you need to set a correlation key in the process using a variable and send the correlation key in the payload as part of the incoming message

Build

You can package the Connector by running the following command:

mvn clean package

This will create the following artifacts:

• A thin JAR without dependencies.
• An uber JAR containing all dependencies, potentially shaded to avoid classpath conflicts. This will not include the SDK artifacts since those are in scope provided and will be brought along by the respective Connector Runtime executing the Connector.

Shading dependencies

You can use the maven-shade-plugin defined in the Maven configuration to relocate common dependencies that are used in other Connectors and the Connector Runtime. This helps to avoid classpath conflicts when the Connector is executed.

Use the relocations configuration in the Maven Shade plugin to define the dependencies that should be shaded. The Maven Shade documentation provides more details on relocations.

API

Connector Properties

This Connector can be configured with the following properties:

Name	Description	Example
Postgres URL	URL of Postgres database	jdbc:postgresql://localhost:5432/postgres
Username	Postgres username to authenticate with	postgres
Password	Password to authenticate with	postgres
Channel	Postgres channel to listen for events	inboundchannel
Polling interval	Long polling interval in seconds	60
Correlation key (process) - for intermediate catch event	Process variable to correlate incoming message	processCorrelationKey
Correlation key (payload) - for intermediate catch event	Correlation key in incoming message	event.payload.messageCorrelationKey
Activation condition - for intermediate catch event	Condition under which the Connector triggers	event.payload.aVariable = 'ok'

Output

This Connector produces the following output:

{
  "event": {
    "payload": "whatever is set in the Postgres trigger, ideally well formed JSON"
  }
}

Test locally

Run unit tests

mvn clean verify

Test with local runtime

Use the Camunda Connector Runtime to run your function as a local Java application.

In your IDE you can also simply navigate to the LocalContainerRuntime class in test scope and run it via your IDE. If necessary, you can adjust application.properties in test scope.

Element Template

The element templates can be found in the element-templates directory.