Activiti 7 Workflow Engine: Concepts, Configuration, Deployment, and Operations

Concept – A workflow automates business processes by passing documents, information, or tasks between participants according to predefined rules to achieve a business goal.

Activiti 7 Overview – Activiti is a BPMN 2.0‑based workflow engine that extracts complex business logic from applications, allowing process definitions to be managed independently, reducing system coupling and maintenance cost.

Maven Dependencies

<dependencies>
    <!-- core engine -->
    <dependency>
        <groupId>org.activiti</groupId>
        <artifactId>activiti-engine</artifactId>
        <version>6.0.0</version>
    </dependency>
    <!-- Spring integration -->
    <dependency>
        <groupId>org.activiti</groupId>
        <artifactId>activiti-spring</artifactId>
        <version>6.0.0</version>
    </dependency>
    ...
</dependencies>

activiti.cfg.xml – The Spring configuration file defines the data source, transaction manager, and engine properties such as databaseSchemaUpdate and mail server settings.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- DBCP connection pool -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/activiti"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
        <property name="maxActive" value="3"/>
        <property name="maxIdle" value="1"/>
    </bean>
    <!-- Process engine configuration -->
    <bean id="processEngineConfiguration"
          class="org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration">
        <property name="dataSource" ref="dataSource"/>
        <property name="databaseSchemaUpdate" value="true"/>
        <property name="asyncExecutorActivate" value="false"/>
        <property name="mailServerHost" value="mail.my-corp.com"/>
        <property name="mailServerPort" value="5025"/>
    </bean>
</beans>

Engine Creation – Two approaches are shown:

// Default engine
ProcessEngine processEngine = ProcessEngines.getDefaultProcessEngine();

// Custom configuration
ProcessEngineConfiguration cfg = ProcessEngineConfiguration
        .createProcessEngineConfigurationFromResource("activiti.cfg.xml");
ProcessEngine processEngine = cfg.buildProcessEngine();

When the engine starts, Activiti creates 25 tables in the database.

Service Interfaces – The engine provides several services accessed via processEngine.getXxxService(): RepositoryService – Deploys and manages process definitions. RuntimeService – Starts process instances and queries runtime data. TaskService – Queries and completes user tasks. HistoryService – Retrieves historical execution data. ManagementService – Engine administration functions.

Process Deployment – Using RepositoryService to deploy a BPMN file (and optional PNG) or a ZIP containing multiple definitions:

public void deployment() {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    Deployment deployment = repo.createDeployment()
        .name("Travel Request")
        .addClasspathResource("bpmn/evection.bpmn")
        .addClasspathResource("bpmn/evection.png")
        .deploy();
    System.out.println("Deployment ID: " + deployment.getId());
}

public void deployProcessByZip() {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    InputStream is = getClass().getClassLoader().getResourceAsStream("bpmn/evection.zip");
    ZipInputStream zip = new ZipInputStream(is);
    Deployment deployment = repo.createDeployment().addZipInputStream(zip).deploy();
    System.out.println("Deployment ID: " + deployment.getId());
}

Starting a Process Instance

public void startProcess() {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RuntimeService runtime = engine.getRuntimeService();
    ProcessInstance instance = runtime.startProcessInstanceByKey("myEvection");
    System.out.println("Definition ID: " + instance.getProcessDefinitionId());
    System.out.println("Instance ID: " + instance.getId());
}

Task Query and Completion

// Query tasks for a specific assignee
List<Task> tasks = taskService.createTaskQuery()
    .processDefinitionKey("myEvection")
    .taskAssignee("zhangsan")
    .list();

// Complete a task
Task task = taskService.createTaskQuery()
    .processDefinitionKey("myProcess_2")
    .taskAssignee("wangcaiwu0")
    .singleResult();
if (task != null) {
    taskService.complete(task.getId(), variablesMap);
}

Suspending and Activating Processes – Both whole process definitions and individual instances can be suspended or activated via RepositoryService or RuntimeService.

// Suspend or activate all instances of a definition
ProcessDefinition pd = repositoryService.createProcessDefinitionQuery()
    .processDefinitionKey("myEvection").singleResult();
if (pd.isSuspended()) {
    repositoryService.activateProcessDefinitionById(pd.getId(), true, null);
} else {
    repositoryService.suspendProcessDefinitionById(pd.getId(), true, null);
}

// Suspend or activate a single instance
ProcessInstance pi = runtimeService.createProcessInstanceQuery()
    .processInstanceId("17501").singleResult();
if (pi.isSuspended()) {
    runtimeService.activateProcessInstanceById(pi.getId());
} else {
    runtimeService.suspendProcessInstanceById(pi.getId());
}

Process Variables – Variables can be set at start time or during task completion. Complex objects must implement Serializable. Example POJO Evection is shown.

@Data @NoArgsConstructor @AllArgsConstructor
public class Evection implements Serializable {
    private Long id;
    private Integer days;
    private String evectionName;
    private Date startTime;
    private Date endTime;
    private String address;
    private String reason;
}

Variables are referenced in BPMN using UEL expressions such as ${assignee} or conditionals like ${days <= 3}.

Gateways – The article explains the four main gateway types:

ExclusiveGateway – chooses a single outgoing flow whose condition evaluates to true.

ParallelGateway – forks into parallel paths and joins them; conditions are ignored.

InclusiveGateway – may take multiple outgoing flows whose conditions are true; joins wait for all active tokens.

EventGateway – not detailed, but mentioned as a control element.

Spring Integration – Provides a full Spring XML configuration that defines the data source, process engine factory bean, and service beans, as well as transaction advice. A Spring Boot application.yml example shows properties for datasource and Activiti (schema update, history level, etc.).

# application.yml
spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/actspring
    username: root
    password: root
activiti:
  database-schema-update: true
  check-process-definitions: false
  db-history-used: true
  history-level: full

The article ends with a call for discussion, community links, and promotional messages.