Inbound MongoDB Connector Template

!!! Work in progress !!!

A starting point to build a Start and Intermediate Inbound MongoDB Connector. Use the Change Stream feature in MongoDB to start process instances or throw intermediate events. Feedback and PRs are welcome! In the Connector you'll need to provide the Mongo DB URL (using a Replica Set or Sharded Cluster topology), database name , optional collection name, and type of event (or all) to monitor.

If you are unfamiliar with how to set up a MongoDB Replica Set, follow these instructions to set one up locally.

Output can be accessed from the event object

event.operationType

event.before

event.after

An example of a MongoDB start event:

A screenshot of MongoDB Compass connected to a replica set:

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	Required
MongoDB URL	URL of MongoDB Server using a Replica Set or Clustered topology	mongodb://localhost:27017,localhost:27018,localhost:27019/?replicaSet=rs0	Yes
MongoDB Database	Name of database to monitor	testdb	Yes
MongoDB Collection	Name of collection to monitor	testcollection	No
MongoDB Event	Name of event to monitor - Insert, Replace, Delete, Any	any	No
Correlation key (process) - for intermediate catch event	Process variable to correlate incoming message	processCorrelationKey	Yes
Correlation key (payload) - for intermediate catch event	Correlation key in incoming message	event.after.someKey	Yes
Activation condition - for intermediate catch event	Condition under which the Connector triggers	event.after.someCondition = 'something'	No

Output

This Connector produces the following output:

{  
  "event": {
    "operationType":"insert",
    "before":"{}",  
    "after": {
      "hello":"world",
      "_id": {
        "date": "Fri Sep 08 18:03:35 BST 2023",
        "timestamp": 1694192615
      }
    }
  }
}

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.