What are the best practices for canceling a request and returning to the previous step?

Camunda 8 Topics
1

Hi,

I have a BPMN model using Camunda 8 and Spring Boot, and I would like to accomplish two things.

First, I want to allow users to cancel the process at any time. To achieve this, I plan to use a parallel gateway, where one of the paths leads to a User Task. If this task is running, it should terminate the process flow.

Second, at one of the steps, I need to check if the time surpasses the current day, which would require returning to the previous step. For this, I am using a Time Boundary Event.

I have provided my Camunda BPMN code below. What are the best practices I should follow for these scenarios? Thank you!

<?xml version="1.0" encoding="UTF-8"?>
<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:zeebe="http://camunda.org/schema/zeebe/1.0" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_01a37ij" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.31.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="8.5.0">
  <bpmn:process id="civil_partnership_payment_order_process" name="buidDiscount" isExecutable="true">
    <bpmn:userTask id="create_payment_order_lnd" name="CREATE">
      <bpmn:extensionElements>
        <zeebe:formDefinition formKey="create_payment_order_lnd" />
      </bpmn:extensionElements>
      <bpmn:incoming>Flow_0r414ln</bpmn:incoming>
      <bpmn:incoming>Flow_17ccf9b</bpmn:incoming>
      <bpmn:incoming>Flow_0px6wn3</bpmn:incoming>
      <bpmn:outgoing>Flow_0rrh299</bpmn:outgoing>
    </bpmn:userTask>
    <bpmn:sequenceFlow id="Flow_0r414ln" sourceRef="StartEvent_1" targetRef="create_payment_order_lnd" />
    <bpmn:sequenceFlow id="Flow_0rrh299" sourceRef="create_payment_order_lnd" targetRef="Gateway_0gapglz" />
    <bpmn:parallelGateway id="Gateway_0gapglz">
      <bpmn:incoming>Flow_0rrh299</bpmn:incoming>
      <bpmn:outgoing>Flow_027jamc</bpmn:outgoing>
      <bpmn:outgoing>Flow_067wy8h</bpmn:outgoing>
    </bpmn:parallelGateway>
    <bpmn:sequenceFlow id="Flow_027jamc" sourceRef="Gateway_0gapglz" targetRef="Activity_1blhfrh" />
    <bpmn:sequenceFlow id="Flow_00rahlc" sourceRef="Activity_1blhfrh" targetRef="Event_0a4lqk7" />
    <bpmn:endEvent id="Event_0a4lqk7">
      <bpmn:incoming>Flow_00rahlc</bpmn:incoming>
      <bpmn:terminateEventDefinition id="TerminateEventDefinition_0iya0h5" />
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="Flow_067wy8h" sourceRef="Gateway_0gapglz" targetRef="lms_announcement_finalization_lnd" />
    <bpmn:exclusiveGateway id="Gateway_0m8tdol">
      <bpmn:incoming>Flow_0beouvl</bpmn:incoming>
      <bpmn:outgoing>Flow_17ccf9b</bpmn:outgoing>
      <bpmn:outgoing>Flow_01yqgzh</bpmn:outgoing>
    </bpmn:exclusiveGateway>
    <bpmn:sequenceFlow id="Flow_0beouvl" sourceRef="lms_announcement_finalization_lnd" targetRef="Gateway_0m8tdol" />
    <bpmn:sequenceFlow id="Flow_17ccf9b" sourceRef="Gateway_0m8tdol" targetRef="create_payment_order_lnd">
      <bpmn:conditionExpression xsi:type="bpmn:tFormalExpression">=lmsAnnouncementFinalizationRevoke=true</bpmn:conditionExpression>
    </bpmn:sequenceFlow>
    <bpmn:sequenceFlow id="Flow_01yqgzh" sourceRef="Gateway_0m8tdol" targetRef="Activity_04wv1js">
      <bpmn:conditionExpression xsi:type="bpmn:tFormalExpression">=lmsAnnouncementFinalizationRevoke=false</bpmn:conditionExpression>
    </bpmn:sequenceFlow>
    <bpmn:receiveTask id="Activity_04wv1js" name="In Progress" messageRef="Message_34h9gfv">
      <bpmn:incoming>Flow_01yqgzh</bpmn:incoming>
      <bpmn:incoming>Flow_19qo79v</bpmn:incoming>
      <bpmn:outgoing>Flow_0ffz97k</bpmn:outgoing>
    </bpmn:receiveTask>
    <bpmn:exclusiveGateway id="Gateway_0lim3al" default="Flow_0mkqmtb">
      <bpmn:incoming>Flow_0ffz97k</bpmn:incoming>
      <bpmn:outgoing>Flow_19qo79v</bpmn:outgoing>
      <bpmn:outgoing>Flow_0mkqmtb</bpmn:outgoing>
    </bpmn:exclusiveGateway>
    <bpmn:sequenceFlow id="Flow_0ffz97k" sourceRef="Activity_04wv1js" targetRef="Gateway_0lim3al" />
    <bpmn:sequenceFlow id="Flow_19qo79v" sourceRef="Gateway_0lim3al" targetRef="Activity_04wv1js" />
    <bpmn:sequenceFlow id="Flow_0mkqmtb" sourceRef="Gateway_0lim3al" targetRef="Event_0dwy0xh" />
    <bpmn:endEvent id="Event_0dwy0xh">
      <bpmn:incoming>Flow_0mkqmtb</bpmn:incoming>
      <bpmn:terminateEventDefinition id="TerminateEventDefinition_1xdvq3f" />
    </bpmn:endEvent>
    <bpmn:startEvent id="StartEvent_1">
      <bpmn:outgoing>Flow_0r414ln</bpmn:outgoing>
      <bpmn:messageEventDefinition id="MessageEventDefinition_098bxwq" />
    </bpmn:startEvent>
    <bpmn:userTask id="lms_announcement_finalization_lnd" name="FINALIZE">
      <bpmn:extensionElements>
        <zeebe:formDefinition formKey="lms_announcement_finalization_lnd" />
      </bpmn:extensionElements>
      <bpmn:incoming>Flow_067wy8h</bpmn:incoming>
      <bpmn:outgoing>Flow_0beouvl</bpmn:outgoing>
    </bpmn:userTask>
    <bpmn:sequenceFlow id="Flow_0px6wn3" sourceRef="Event_1xregc1" targetRef="create_payment_order_lnd" />
    <bpmn:boundaryEvent id="Event_1xregc1" attachedToRef="Activity_04wv1js">
      <bpmn:outgoing>Flow_0px6wn3</bpmn:outgoing>
      <bpmn:timerEventDefinition id="TimerEventDefinition_0cw97yh">
        <bpmn:timeDate xsi:type="bpmn:tFormalExpression">=dueDate</bpmn:timeDate>
      </bpmn:timerEventDefinition>
    </bpmn:boundaryEvent>
    <bpmn:userTask id="Activity_1blhfrh" name="CANCEL">
      <bpmn:extensionElements>
        <zeebe:userTask />
      </bpmn:extensionElements>
      <bpmn:incoming>Flow_027jamc</bpmn:incoming>
      <bpmn:outgoing>Flow_00rahlc</bpmn:outgoing>
    </bpmn:userTask>
  </bpmn:process>
  <bpmn:message id="Message_34h9gfv" name="execution_order_issuance_message">
    <bpmn:extensionElements>
      <zeebe:subscription correlationKey="=processInstanceId" />
    </bpmn:extensionElements>
  </bpmn:message>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="civil_partnership_payment_order_process">
      <bpmndi:BPMNShape id="Activity_08nwxpy_di" bpmnElement="create_payment_order_lnd">
        <dc:Bounds x="260" y="180" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Gateway_1kodaw1_di" bpmnElement="Gateway_0gapglz">
        <dc:Bounds x="405" y="195" width="50" height="50" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1muwy3s_di" bpmnElement="Event_0a4lqk7">
        <dc:Bounds x="542" y="302" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="528" y="345" width="64" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Gateway_0m8tdol_di" bpmnElement="Gateway_0m8tdol" isMarkerVisible="true">
        <dc:Bounds x="655" y="195" width="50" height="50" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0r62exq_di" bpmnElement="Activity_04wv1js">
        <dc:Bounds x="750" y="180" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Gateway_0lim3al_di" bpmnElement="Gateway_0lim3al" isMarkerVisible="true">
        <dc:Bounds x="905" y="195" width="50" height="50" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0qavxjl_di" bpmnElement="Event_0dwy0xh">
        <dc:Bounds x="912" y="302" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="890" y="345" width="81" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_17nfw7p_di" bpmnElement="StartEvent_1">
        <dc:Bounds x="182" y="202" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="158" y="245" width="84" height="66" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0x6vj41_di" bpmnElement="lms_announcement_finalization_lnd">
        <dc:Bounds x="510" y="180" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_1x9c0nb_di" bpmnElement="Activity_1blhfrh">
        <dc:Bounds x="380" y="280" width="100" height="80" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_16n813f_di" bpmnElement="Event_1xregc1">
        <dc:Bounds x="782" y="162" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_0r414ln_di" bpmnElement="Flow_0r414ln">
        <di:waypoint x="218" y="220" />
        <di:waypoint x="260" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0rrh299_di" bpmnElement="Flow_0rrh299">
        <di:waypoint x="360" y="220" />
        <di:waypoint x="405" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_027jamc_di" bpmnElement="Flow_027jamc">
        <di:waypoint x="430" y="245" />
        <di:waypoint x="430" y="280" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_00rahlc_di" bpmnElement="Flow_00rahlc">
        <di:waypoint x="480" y="320" />
        <di:waypoint x="542" y="320" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_067wy8h_di" bpmnElement="Flow_067wy8h">
        <di:waypoint x="455" y="220" />
        <di:waypoint x="510" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0beouvl_di" bpmnElement="Flow_0beouvl">
        <di:waypoint x="610" y="220" />
        <di:waypoint x="655" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_17ccf9b_di" bpmnElement="Flow_17ccf9b">
        <di:waypoint x="680" y="195" />
        <di:waypoint x="680" y="140" />
        <di:waypoint x="330" y="140" />
        <di:waypoint x="330" y="180" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_01yqgzh_di" bpmnElement="Flow_01yqgzh">
        <di:waypoint x="705" y="220" />
        <di:waypoint x="750" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0ffz97k_di" bpmnElement="Flow_0ffz97k">
        <di:waypoint x="850" y="220" />
        <di:waypoint x="905" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_19qo79v_di" bpmnElement="Flow_19qo79v">
        <di:waypoint x="930" y="195" />
        <di:waypoint x="930" y="140" />
        <di:waypoint x="830" y="140" />
        <di:waypoint x="830" y="180" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="836" y="122" width="88" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0mkqmtb_di" bpmnElement="Flow_0mkqmtb">
        <di:waypoint x="930" y="245" />
        <di:waypoint x="930" y="302" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0px6wn3_di" bpmnElement="Flow_0px6wn3">
        <di:waypoint x="800" y="160" />
        <di:waypoint x="800" y="110" />
        <di:waypoint x="310" y="110" />
        <di:waypoint x="310" y="180" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="526" y="92" width="58" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>
2

Hi @Sina_Mehrad - I think a critical piece of information that will help inform the model design is how the process should be canceled. Is the workflow of “A user logs into Tasklist, finds the waiting user task, claims it, then completes it” the correct workflow? Or might there be a button you click inside your application that triggers the cancellation? Or a message from an external system, like Kafka?

All of those scenarios can be modeled, but I think a good first step is to decide what your intended cancellation flow looks like and then design the model, rather than having the model decide the flow.

1 Like
3

Hi, thank you for your response. In my scenario, the flow should be canceled when a user clicks a button.

And do you know how to return to the previous step after a specific time? I want to learn the best practice.

4

@Sina_Mehrad - when a user clicks a button where?

Returning to a previous step depends on whether you want to rollback anything that happened in between, or if you just want the token to return to and repeat a previous step. You could use an interrupting timer boundary event and a link even to go back; or if you need to rollback anything, you would want to use a compensation event with the timer.

1 Like