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Flowable Event Registry Demo

Some demo code on how to use the event registry in flowable 6.5.0.

note I'm no expert -- I just used the docs and the source code to find out how to use this.

Prerequisites

  • A RabbitMQ installation on localhost using the default (insecure!) credentials.

Example Use Case

Let's assume we have some system which sends messages to RabbitMQ which are JSON encoded and looks like so:

{
  "eventKeyValue": "myEvent",
  "customerName": "nexiles",
  "amount": 42
}

We want flowable to look for events -- e.g. messages of this kind and start a business process for each message / event.

Testing

  • make sure RabbitMQ is running
  • Start the application
  • Using the RabbitMQ UI:
    • navigate to the "flowable-inbound" queue
    • publish a message - !!make sure that you set "content_type" to "application/json" in the "properties"!!

You should see something like this:

2020-03-18 19:36:24.454  INFO 58827 --- [           main] c.n.e.f.FlowableEventRegistryApplication : Application started.
2020-03-18 19:36:24.455  INFO 58827 --- [           main] c.n.e.f.FlowableEventRegistryApplication : Processes deployed: 1
2020-03-18 19:36:24.456  INFO 58827 --- [           main] c.n.e.f.FlowableEventRegistryApplication : Events deployed:    1
2020-03-18 19:37:00.726  INFO 58827 --- [         task-1] c.n.e.flowableeventregistry.Logger       : LOG: Process eventTest:1:5eed0edf-6947-11ea-a2e5-6ab7c11ecb8d activity theTask: nexiles
2020-03-18 19:37:00.727 DEBUG 58827 --- [         task-1] c.n.e.flowableeventregistry.Logger       : LOG: var amount := 42
2020-03-18 19:37:00.727 DEBUG 58827 --- [         task-1] c.n.e.flowableeventregistry.Logger       : LOG: var customerName := nexiles
2020-03-18 19:37:02.675  INFO 58827 --- [         task-2] c.n.e.flowableeventregistry.Logger       : LOG: Process eventTest:1:5eed0edf-6947-11ea-a2e5-6ab7c11ecb8d activity theTask: nexiles
2020-03-18 19:37:02.675 DEBUG 58827 --- [         task-2] c.n.e.flowableeventregistry.Logger       : LOG: var amount := 42
2020-03-18 19:37:02.675 DEBUG 58827 --- [         task-2] c.n.e.flowableeventregistry.Logger       : LOG: var customerName := nexiles
2020-03-18 19:37:03.260  INFO 58827 --- [         task-3] c.n.e.flowableeventregistry.Logger       : LOG: Process eventTest:1:5eed0edf-6947-11ea-a2e5-6ab7c11ecb8d activity theTask: nexiles
2020-03-18 19:37:03.260 DEBUG 58827 --- [         task-3] c.n.e.flowableeventregistry.Logger       : LOG: var amount := 42
2020-03-18 19:37:03.260 DEBUG 58827 --- [         task-3] c.n.e.flowableeventregistry.Logger       : LOG: var customerName := nexiles

What does the code do

  • Define a inbound channel -- inbound.channel in resources/eventregistry
  • Define the event -- event-one.event in resources/eventregistry
  • Define a process -- event-test-process.bpmn20.xml in resources/processes

inbound channel

Defines a channel where flowable listens for events.

  • It's a "inbound" channel -- messages flow from the queue to flowable
  • We use rabbitmq
  • Our messages are JSON
  • The messages we receive have a JSON Field "eventKeyValue" which defines the event type. See above, the event type is "myEvent" for the example message.
  • We want flowable to bind to the queue "flowable-inbound". This is a queue which must exist in RabbitMQ and our messages must be routed to this queue.

Inbound channel:

{
      "key": "testChannel",
      "category": "channel",
      "name": "Test channel",
      "description": "test Inbound Channel",
      "channelType": "inbound",
      "type": "rabbit",
      "deserializerType": "json",
      "channelEventKeyDetection": {
        "jsonField": "eventKeyValue"
      },
      "queues": ["flowable-inbound"]
}

Event Definition

This defines the shape of the message and a binding to the inbound channel. I don't yet know what the other stuff means :)

{
  "key": "myEvent",
  "name": "My event",
  "inboundChannelKeys": [
    "test-channel"
  ],
  "correlationParameters": [
    {
      "name": "customerId",
      "type": "string"
    }
  ],
  "payload": [
    {
      "name": "customerName",
      "type": "string"
    },
    {
      "name": "foo",
      "type": "string"
    },
    {
      "name": "amount",
      "type": "integer"
    }
  ]
}

Process

So finally we define a BPMN process.

  • The startEvent refers to our event type myEvent

  • We define two mappings from event payload to business process variable:

    • customerName -> customerName
    • amount -> amount

  • The script task uses the Logger bean to log a message.

      <process id="eventTest" name="Process to test events">
      <startEvent id="theStart" >
          <extensionElements>
              <flowable:eventType xmlns:flowable="http://flowable.org/bpmn">myEvent</flowable:eventType>
              <flowable:eventOutParameter xmlns:flowable="http://flowable.org/bpmn"
                                          source="customerName"
                                          sourceType="string"
                                          target="customerName"/>
              <flowable:eventOutParameter xmlns:flowable="http://flowable.org/bpmn"
                                          source="amount"
                                          sourceType="integer"
                                          target="amount"/>
          </extensionElements>
      </startEvent>
      <sequenceFlow id="flow1" sourceRef="theStart" targetRef="theTask" />
      <serviceTask id="theTask" name="my task" flowable:expression="#{Logger.log(execution, customerName)}" />
      <sequenceFlow id="flow2" sourceRef="theTask" targetRef="theEnd" />
      <endEvent id="theEnd" />
  </process>