Integrating Camunda 7 Workflow Engine with Spring Boot: Concepts, Configuration, and API Usage

Concepts

Defines key terms such as Process, Process Instance, Variables, Task, and Deployment in the Camunda BPMN context.

Core Components

Describes the Process Engine and the web-based management application provided by Camunda.

API Overview

Provides a link to the official Camunda Process Engine API documentation.

Spring Boot Integration

Dependencies

<dependency>
    <groupId>org.camunda.bpm.springboot</groupId>
    <artifactId>camunda-bpm-spring-boot-starter</artifactId>
    <version>7.18.0</version>
</dependency>
<dependency>
    <groupId>org.camunda.bpm.springboot</groupId>
    <artifactId>camunda-bpm-spring-boot-starter-rest</artifactId>
    <version>7.18.0</version>
</dependency>
<dependency>
    <groupId>org.camunda.bpm.springboot</groupId>
    <artifactId>camunda-bpm-spring-boot-starter-webapp</artifactId>
    <version>7.18.0</version>
</dependency>

Database : Uses MySQL; Camunda creates required tables automatically.

POM snippet

<project xmlns="http://maven.apache.org/POM/4.0.0" ...>
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.3</version>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>camunda-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        ... (Camunda and MySQL dependencies) ...
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.yml

server:
  port: 8081

camunda.bpm:
  admin-user:
    id: admin
    password: 123456
    firstName: yu
  filter:
    create: All tasks

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:8101/camunda
    username: root
    password: 123456
    type: com.mysql.cj.jdbc.MysqlDataSource

Running the Application

After starting, Camunda’s web console is available at http://localhost:8081/ with the admin credentials defined above. The engine automatically creates the required tables (e.g., ACT_ID_, ACT_HI_, ACT_RE_, ACT_RU_, ACT_GE_).

Process Modeling

Use Camunda Modeler to design BPMN diagrams. The article shows an example OA‑style process with user tasks, service tasks, and various gateways (exclusive, parallel, inclusive).

Task Types

User Task : Requires manual completion via taskService.complete(taskId, variables); .

Service Task : Executed automatically by the engine.

Gateways

Explains exclusive, parallel, and inclusive gateways and how conditions are evaluated using process variables.

API Usage

Process APIs

ProcessInstance instance = runtimeService.startProcessInstanceByKey(processKey, params);
runtimeService.suspendProcessInstanceById(instance.getId());
runtimeService.activateProcessInstanceById(instance.getId());
runtimeService.deleteProcessInstance(instance.getId(), "manual delete");

Task APIs

List<Task> tasks = taskService.createTaskQuery().orderByTaskCreateTime().desc().list();
Task activeTask = taskService.createTaskQuery().taskId(taskId).active().singleResult();
List<HistoricTaskInstance> history = historyService.createHistoricTaskInstanceQuery().processInstanceId(instanceId).list();

Variable APIs

runtimeService.setVariable(instance.getId(), "PATIENT_ID", relatedId);
Object var = runtimeService.getVariable(instance.getId(), "GENERAL_ID");
HistoricVariableInstance histVar = historyService.createHistoricVariableInstanceQuery()
    .processInstanceId(instance.getId()).variableName("PATIENT_ID").singleResult();

Listeners and Extensions

Shows how to define TaskListener and ExecutionListener beans using lambda expressions, as well as delegate expressions for JavaDelegate implementations. Also covers extension properties for custom attributes.

Identity and Authorization

Demonstrates setting the authenticated user via identityService.setAuthenticatedUserId(UserUtil.getUserId().toString()); and retrieving it from the engine’s context.

Conclusion

The article ends with a call for readers to like, share, and follow the author’s public account for more advanced Spring Cloud, Spring Boot, and MyBatis tutorials.