Building a Leave Approval Workflow with Flowable UI and Spring Boot

Overview

The tutorial demonstrates how to use Flowable’s built‑in UI (flowable‑ui) to create a BPMN diagram and then develop a Spring Boot backend that executes the workflow.

1. Deploying flowable‑ui

Download https://github.com/flowable/flowable-engine/releases/download/flowable-6.6.0/flowable-6.6.0.zip , extract flowable-6.6.0\wars\flowable-ui.war , and deploy it to Tomcat. Access the UI at http://localhost:8080/flowable-ui with credentials admin/test . Use the APP.MODELER to design the process and export the BPMN file.

2. Designing the BPMN diagram

The diagram includes basic Flowable elements: event , sequence flow , gateway , and user task . The example models a leave request that passes through student, teacher, and principal approval steps, with conditional gateways based on the variable command (agree/refuse).

3. Backend project setup

The backend is a Spring Boot 2.3.0 application running on JDK 8. Maven dependencies include org.flowable:flowable-spring-boot-starter:6.6.0 and mysql:mysql-connector-java:5.1.45 . The application.yml configures a MySQL datasource.

4. Flowable database tables

Flowable creates tables prefixed with ACT_ :

ACT_RE_ : repository tables (process definitions, models).

ACT_RU_ : runtime tables (tasks, executions, variables).

ACT_HI_ : history tables (completed instances, tasks).

ACT_GE_ : generic tables (byte arrays, properties).

Additional tables manage users, groups, and identity links.

5. Engine API usage

The main services are:

RepositoryService – deploy and query process definitions.

RuntimeService – start process instances.

TaskService – query, claim, and complete user tasks.

IdentityService – manage users and groups.

HistoryService – query completed instances and tasks.

Sample Java code shows how to deploy a ZIP of BPMN files, start a process, claim and complete tasks for the student and teacher groups, pass variables to gateways, and query historic data.

import lombok.extern.slf4j.Slf4j;
import org.flowable.engine.*;
import org.flowable.engine.history.*;
import org.flowable.engine.repository.*;
import org.flowable.engine.runtime.*;
import org.flowable.idm.api.*;
import org.flowable.task.api.*;
import org.springframework.beans.factory.annotation.Autowired;
import java.io.*;
import java.util.*;

@Slf4j
public class TestFlowable {
    @Autowired private RepositoryService repositoryService;
    @Autowired private RuntimeService runtimeService;
    @Autowired private HistoryService historyService;
    @Autowired private org.flowable.engine.TaskService taskService;
    @Autowired private org.flowable.engine.IdentityService identityService;
    public void createDeploymentZip() {
        try {
            File zipTemp = new File("f:/leave_approval.bpmn20.zip");
            ZipInputStream zipInputStream = new ZipInputStream(new FileInputStream(zipTemp));
            Deployment deployment = repositoryService.createDeployment()
                .addZipInputStream(zipInputStream)
                .deploy();
            log.info("部署成功:{}", deployment.getId());
        } catch (FileNotFoundException e) { e.printStackTrace(); }
        // ... (rest of the steps: query definitions, start process, claim/complete tasks, query history)
    }
}

6. References

Links to Flowable documentation, Chinese translations, and related blog posts are provided for further reading.