Event Listener

An example of a Concord Server plugin. It creates a new WebSocket endpoint (/events), listens for all process events and broadcasts them to all active subscribers.

Usage

• compile with mvn package;
• copy target/event-listener-plugin-*.jar into an ext directory somewhere on the filesystem;
• mount the ext directory to the Concord Server Docker container:

docker run \
...
-v "/path/to/host/ext:/opt/concord/server/ext:ro" \
...
walmartlabs/concord-server

If everything is okay you should see something like this in the Server's log:

12:21:25.830 [main] [INFO ] [] c.i.c.e.ProcessEventsWebSocket - The /events socket is configured

Connect to the endpoint using any WebSocket client (e.g. https://github.com/vi/websocat):

$ websocat ws://localhost:8001/events/${processId}

Replace ${processId} with the ID of a process which events you wish to receive.

You can run it several times in different terminal windows to simulate multiple subscribers.

Start one or more Concord processes. You should see a stream of events in the websocat's terminal:

[{"processKey":{"instanceId":"c028de4b-851a-45f2-b4d4-b0b31f470c4c","createdAt":1582824616684},"eventType":"PROCESS_STATUS","eventDate":null,"data":{"status":"NEW"}}]
[{"processKey":{"instanceId":"c028de4b-851a-45f2-b4d4-b0b31f470c4c","createdAt":1582824616684},"eventType":"PROCESS_STATUS","eventDate":null,"data":{"status":"ENQUEUED"}}]
[{"processKey":{"instanceId":"c028de4b-851a-45f2-b4d4-b0b31f470c4c","createdAt":1582824616684},"eventType":"PROCESS_STATUS","eventDate":null,"data":{"status":"STARTING"}}]
[{"processKey":{"instanceId":"c028de4b-851a-45f2-b4d4-b0b31f470c4c","createdAt":1582824616684},"eventType":"PROCESS_STATUS","eventDate":null,"data":{"status":"RUNNING"}}]
...etc...