External Task Client Implementation in Camunda With Spring Boot Application
See how to use Spring Boot starter dependency to run the external task in Camunda.
By
·
·
Tutorial
Likes
(5)
Likes
There are no likes...yet! 👀
Be the first to like this post!
It looks like you're not logged in.
Sign in to see who liked this post!
Comment
Save
10.6K Views
Join the DZone community and get the full member experience.
Join For FreeToday, we will be using Spring Boot starter dependency to run the external task in Camunda.
Create a Spring Boot project with the embedded Camunda Engine using this link. Use version 7.15.0.
Other Requirements:
- Spring Boot 2.4.3
- Camunda 7.15.0
- Eclipse or any other IDE
- Maven
Import the Maven project into Eclipse and add the below-mentioned files.
Add below additional dependency to the pom.xml file.
XML
<dependency>
<groupId>org.camunda.bpm.springboot</groupId>
<artifactId>camunda-bpm-spring-boot-starter-external-task-client</artifactId>
<version>7.15.0</version>
</dependency>Use Camunda modeler to save the below XML content with .bpmn extension to get the process model, which is having external service tasks as component.
XML
<?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:camunda="http://camunda.org/schema/1.0/bpmn" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" id="Definitions_1q1cbhv" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="3.4.1">
<bpmn:process id="externalTaskClientProcess" name="External Task Client" isExecutable="true">
<bpmn:startEvent id="StartEvent_1" name="Start">
<bpmn:extensionElements>
<camunda:executionListener event="start">
<camunda:script scriptFormat="Groovy">println("process started")</camunda:script>
</camunda:executionListener>
</bpmn:extensionElements>
<bpmn:outgoing>SequenceFlow_1hatjbw</bpmn:outgoing>
</bpmn:startEvent>
<bpmn:sequenceFlow id="SequenceFlow_1hatjbw" sourceRef="StartEvent_1" targetRef="Task_08imlsr" />
<bpmn:serviceTask id="Task_08imlsr" name="Get Interview Rating (1 to 10)" camunda:type="external" camunda:topic="ratingProvider">
<bpmn:incoming>SequenceFlow_1hatjbw</bpmn:incoming>
<bpmn:outgoing>SequenceFlow_1x5a8md</bpmn:outgoing>
</bpmn:serviceTask>
<bpmn:exclusiveGateway id="ExclusiveGateway_0hmq2sa">
<bpmn:incoming>SequenceFlow_1x5a8md</bpmn:incoming>
<bpmn:outgoing>SequenceFlow_08h0v2e</bpmn:outgoing>
<bpmn:outgoing>SequenceFlow_0p8irmo</bpmn:outgoing>
</bpmn:exclusiveGateway>
<bpmn:sequenceFlow id="SequenceFlow_1x5a8md" sourceRef="Task_08imlsr" targetRef="ExclusiveGateway_0hmq2sa" />
<bpmn:sequenceFlow id="SequenceFlow_08h0v2e" name="Rating > 6" sourceRef="ExclusiveGateway_0hmq2sa" targetRef="Task_1g5ymte">
<bpmn:conditionExpression xsi:type="bpmn:tFormalExpression">${candidateScore > 6}</bpmn:conditionExpression>
</bpmn:sequenceFlow>
<bpmn:sequenceFlow id="SequenceFlow_0p8irmo" name="Rating <= 6" sourceRef="ExclusiveGateway_0hmq2sa" targetRef="Task_0f7ms7k">
<bpmn:conditionExpression xsi:type="bpmn:tFormalExpression">${candidateScore <= 6}</bpmn:conditionExpression>
</bpmn:sequenceFlow>
<bpmn:exclusiveGateway id="ExclusiveGateway_0gfoi7x">
<bpmn:incoming>SequenceFlow_05v92zi</bpmn:incoming>
<bpmn:incoming>SequenceFlow_1g31asm</bpmn:incoming>
<bpmn:outgoing>SequenceFlow_18vlx25</bpmn:outgoing>
</bpmn:exclusiveGateway>
<bpmn:sequenceFlow id="SequenceFlow_05v92zi" sourceRef="Task_0f7ms7k" targetRef="ExclusiveGateway_0gfoi7x" />
<bpmn:endEvent id="EndEvent_01rktcj" name="End">
<bpmn:incoming>SequenceFlow_18vlx25</bpmn:incoming>
</bpmn:endEvent>
<bpmn:sequenceFlow id="SequenceFlow_18vlx25" sourceRef="ExclusiveGateway_0gfoi7x" targetRef="EndEvent_01rktcj" />
<bpmn:sequenceFlow id="SequenceFlow_1g31asm" sourceRef="Task_1g5ymte" targetRef="ExclusiveGateway_0gfoi7x" />
<bpmn:serviceTask id="Task_1g5ymte" name="Get Rating" camunda:type="external" camunda:topic="candidateRating">
<bpmn:incoming>SequenceFlow_08h0v2e</bpmn:incoming>
<bpmn:outgoing>SequenceFlow_1g31asm</bpmn:outgoing>
</bpmn:serviceTask>
<bpmn:scriptTask id="Task_0f7ms7k" name="Candidate Rejected" scriptFormat="Groovy">
<bpmn:incoming>SequenceFlow_0p8irmo</bpmn:incoming>
<bpmn:outgoing>SequenceFlow_05v92zi</bpmn:outgoing>
<bpmn:script>println ("Candidate with score: " + candidateScore +" is rejected.");</bpmn:script>
</bpmn:scriptTask>
<bpmn:textAnnotation id="TextAnnotation_1qzfqxc">
<bpmn:text>ratingProvider</bpmn:text>
</bpmn:textAnnotation>
<bpmn:association id="Association_0ce5iq8" sourceRef="Task_08imlsr" targetRef="TextAnnotation_1qzfqxc" />
<bpmn:textAnnotation id="TextAnnotation_0vo2qx6">
<bpmn:text>candidateRating</bpmn:text>
</bpmn:textAnnotation>
<bpmn:association id="Association_0y3fb6h" sourceRef="Task_1g5ymte" targetRef="TextAnnotation_0vo2qx6" />
</bpmn:process>
<bpmndi:BPMNDiagram id="BPMNDiagram_1">
<bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="externalTaskClientProcess">
<bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
<dc:Bounds x="179" y="269" width="36" height="36" />
<bpmndi:BPMNLabel>
<dc:Bounds x="185" y="312" width="25" height="14" />
</bpmndi:BPMNLabel>
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="SequenceFlow_1hatjbw_di" bpmnElement="SequenceFlow_1hatjbw">
<di:waypoint x="215" y="287" />
<di:waypoint x="270" y="287" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="ServiceTask_0ark1zc_di" bpmnElement="Task_08imlsr">
<dc:Bounds x="270" y="247" width="100" height="80" />
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="ExclusiveGateway_0hmq2sa_di" bpmnElement="ExclusiveGateway_0hmq2sa" isMarkerVisible="true">
<dc:Bounds x="425" y="262" width="50" height="50" />
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="SequenceFlow_1x5a8md_di" bpmnElement="SequenceFlow_1x5a8md">
<di:waypoint x="370" y="287" />
<di:waypoint x="425" y="287" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="SequenceFlow_08h0v2e_di" bpmnElement="SequenceFlow_08h0v2e">
<di:waypoint x="450" y="262" />
<di:waypoint x="450" y="200" />
<di:waypoint x="550" y="200" />
<bpmndi:BPMNLabel>
<dc:Bounds x="454" y="183" width="51" height="14" />
</bpmndi:BPMNLabel>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="SequenceFlow_0p8irmo_di" bpmnElement="SequenceFlow_0p8irmo">
<di:waypoint x="450" y="312" />
<di:waypoint x="450" y="400" />
<di:waypoint x="550" y="400" />
<bpmndi:BPMNLabel>
<dc:Bounds x="451" y="403" width="57" height="14" />
</bpmndi:BPMNLabel>
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="ExclusiveGateway_0gfoi7x_di" bpmnElement="ExclusiveGateway_0gfoi7x" isMarkerVisible="true">
<dc:Bounds x="715" y="262" width="50" height="50" />
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="SequenceFlow_05v92zi_di" bpmnElement="SequenceFlow_05v92zi">
<di:waypoint x="650" y="400" />
<di:waypoint x="740" y="400" />
<di:waypoint x="740" y="312" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="EndEvent_01rktcj_di" bpmnElement="EndEvent_01rktcj">
<dc:Bounds x="822" y="269" width="36" height="36" />
<bpmndi:BPMNLabel>
<dc:Bounds x="830" y="312" width="20" height="14" />
</bpmndi:BPMNLabel>
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="SequenceFlow_18vlx25_di" bpmnElement="SequenceFlow_18vlx25">
<di:waypoint x="765" y="287" />
<di:waypoint x="822" y="287" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="SequenceFlow_1g31asm_di" bpmnElement="SequenceFlow_1g31asm">
<di:waypoint x="650" y="200" />
<di:waypoint x="740" y="200" />
<di:waypoint x="740" y="262" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="ServiceTask_0ktpo8l_di" bpmnElement="Task_1g5ymte">
<dc:Bounds x="550" y="160" width="100" height="80" />
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="ScriptTask_0jfnbcz_di" bpmnElement="Task_0f7ms7k">
<dc:Bounds x="550" y="360" width="100" height="80" />
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="TextAnnotation_1qzfqxc_di" bpmnElement="TextAnnotation_1qzfqxc">
<dc:Bounds x="370" y="160" width="100" height="30" />
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="Association_0ce5iq8_di" bpmnElement="Association_0ce5iq8">
<di:waypoint x="356" y="247" />
<di:waypoint x="407" y="190" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="TextAnnotation_0vo2qx6_di" bpmnElement="TextAnnotation_0vo2qx6">
<dc:Bounds x="650" y="80" width="100" height="30" />
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="Association_0y3fb6h_di" bpmnElement="Association_0y3fb6h">
<di:waypoint x="638" y="160" />
<di:waypoint x="686" y="110" />
</bpmndi:BPMNEdge>
</bpmndi:BPMNPlane>
</bpmndi:BPMNDiagram>
</bpmn:definitions>If seen the saved content in diagram view in modeler, below is the diagram that should be there.
Add the below code snippet in application.yaml.
YAML
camunda.bpm.client:
base-url: http://localhost:8080/engine-rest #URL of Process Engine
lock-duration: 20000 # time in ms & external task will be locked
subscriptions:
ratingProvider:
variable-names: []
process-definition-key: externalTaskClientProcess
candidateRating:
variable-names: candidateScore
process-definition-key: externalTaskClientProcessAdd the below external task implementations used in the process model namely ratingProvider and candidateRating.
Java
package com.example.workflow;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.camunda.bpm.client.spring.annotation.ExternalTaskSubscription;
import org.camunda.bpm.client.task.ExternalTask;
import org.camunda.bpm.client.task.ExternalTaskHandler;
import org.camunda.bpm.client.task.ExternalTaskService;
import org.camunda.bpm.engine.variable.VariableMap;
import org.camunda.bpm.engine.variable.Variables;
import org.springframework.stereotype.Component;
@Component
@ExternalTaskSubscription("ratingProvider")
public class GenerateRatingHandler implements ExternalTaskHandler {
Logger logger = Logger.getLogger("GenerateRatingHandler");
@Override
public void execute(ExternalTask externalTask, ExternalTaskService externalTaskService) {
String candidateId = "IN-" + (Math.random() * 100);
int candidateScore = (int) (Math.random() * 11);
VariableMap variables = Variables.createVariables();
variables.put("candidateId", candidateId);
variables.put("candidateScore", candidateScore);
externalTaskService.complete(externalTask, variables);
logger.log(Level.INFO, "NOPE Rating Genrator External task is completed for Candidate {0} with rating {1}", new Object[]{candidateId, candidateScore});
}
}
Java
package com.example.workflow;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.camunda.bpm.client.spring.annotation.ExternalTaskSubscription;
import org.camunda.bpm.client.task.ExternalTask;
import org.camunda.bpm.client.task.ExternalTaskHandler;
import org.camunda.bpm.client.task.ExternalTaskService;
import org.springframework.stereotype.Component;
@Component
@ExternalTaskSubscription("candidateRating")
public class CandidateRatingHanlder implements ExternalTaskHandler {
Logger logger = Logger.getLogger("CandidateRatingHanlder");
@Override
public void execute(ExternalTask externalTask, ExternalTaskService externalTaskService) {
int candidateScore = externalTask.getVariable("candidateScore");
//Logic to process based on rating goes here
externalTaskService.complete(externalTask);
logger.log(Level.INFO, "Processing candidate Score received {0}", new Object[]{ candidateScore});
}
}
Run the application using the main class file and observe the output where the external tasks implemented in the Spring Boot project will be getting executed.
Spring Framework
Spring Boot
Task (computing)
Camunda
application
Implementation
Opinions expressed by DZone contributors are their own.
Comments