Spring Boot + Activiti Script Task Example

By Atul Rai | Last Updated: May 11, 2019 Previous       Next

This page will walk through Spring Boot + Activiti Script Task example. A script task is an automatic activity. When process execution arrives at the script task, the corresponding script is executed. A script task is visualized as a typical BPMN 2.0 task (rounded rectangle), with a small script icon in the top-left corner of the rectangle.

Activiti workflow engine supports two types of script:

1. Groovy
2. javascript

Note: Don’t confuse about JavaScript (we are not going to alert/console something on the web browser), it’s all about Java scripting,  javascript engine that is embedded in the JDK, using the ScriptEngine class in the JDK. In JDK 6/7 this was Rhino, in JDK 8 this is Nashorn.

1. Technologies Used

Find the list of all technologies used in this application.

1. STS 4
2. JDK 8
3. Spring Boot 1.5.20.RELEASE
4. Activiti 5.22.0
5. H2 Database
6. groovy-all-2.4.16.jar

Similar Posts:

1. Spring Boot + Activiti Service Task Example
2. Spring Boot + Activiti Example

2. Dependencies Required

To make it work, make sure these following dependencies are available in your build path. Add the following to your pom.xml.

<properties>
	<java.version>1.8</java.version>
	<activiti.version>5.22.0</activiti.version>
</properties>
<dependencies>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<dependency>
		<groupId>org.activiti</groupId>
		<artifactId>activiti-spring-boot-starter-basic</artifactId>
		<version>${activiti.version}</version>
	</dependency>
	<dependency>
		<groupId>com.h2database</groupId>
		<artifactId>h2</artifactId>
	</dependency>
	<dependency>
		<groupId>org.codehaus.groovy</groupId>
		<artifactId>groovy-all</artifactId>
	</dependency>
</dependencies>

3. Groovy Script Task

To execute the Groovy script in the workflow, a script task is defined by specifying the attribute scriptFormat="groovy" and the statement must be in the script tag.

<scriptTask id="groovyScriptTask" name="Groovy Script Task" scriptFormat="groovy">
	<script>
		println '**** Groovy Script Task executed successfully ****'
	</script>
</scriptTask>

3.1 BPMN Process Definition

Drop the BPMN 2.0 process definition into the src/main/resources/processes folder. See the complete BPMN process definition for Groovy script task.

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:activiti="http://activiti.org/bpmn"
	xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC"
	xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema"
	expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.activiti.org/test">
	<process id="groovy-script-task-process" name="Activiti Script Task using Groovy" isExecutable="true">
		<startEvent id="startevent1" name="Start"></startEvent>
		<scriptTask id="groovyScriptTask" name="Groovy Script Task" scriptFormat="groovy" activiti:autoStoreVariables="false">
			<script>
				println '**** Groovy Script Task executed successfully ****'
			</script>
		</scriptTask>
		<sequenceFlow id="flow1" sourceRef="startevent1" targetRef="groovyScriptTask"></sequenceFlow>
		<endEvent id="endevent1" name="End"></endEvent>
		<sequenceFlow id="flow2" sourceRef="groovyScriptTask" targetRef="endevent1"></sequenceFlow>
	</process>
</definitions>

The above BPMN process definition gives you the below-visualized diagram:

3.2 Execute it

Create a class which autowired the RuntimeService and execute the process by its process instance key.

package org.websparrow.activiti.controller;

import org.activiti.engine.RuntimeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/activiti")
public class ScriptTaskController {

	@Autowired
	private RuntimeService runtimeService;

	@GetMapping("script-task/groovy")
	public String groovyScritTask() {

		runtimeService.startProcessInstanceByKey("groovy-script-task-process");

		return "check the console log...";
	}
}

Output: Hit the http://localhost:8080/activiti/script-task/groovy URL in your web browser and check your IDE console log. You will get the:

**** Groovy Script Task executed successfully ****

4. javascript Script Task

A script task is defined by specifying the attribute scriptFormat="javascript" and the statement must be in the script tag.

<scriptTask id="jsScriptTask" name="JS Script Task" scriptFormat="javascript" >
	<script>
		java.lang.System.out.println("Hello Websparrow.org");				
	</script>
</scriptTask>

OR

<scriptTask id="jsScriptTask" name="JS Script Task" scriptFormat="javascript" >
	<script>
		var my = "Activiti is an open-source workflow engine.";
		print(my);				
	</script>
</scriptTask>

4.1 BPMN Process Definition

See the complete BPMN process definition for javascript script task.

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:activiti="http://activiti.org/bpmn"
	xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC"
	xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema"
	expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.activiti.org/test">
	<process id="js-script-task-process" name="Activiti Script Task using Groovy" isExecutable="true">
		<startEvent id="startevent1" name="Start"></startEvent>
		<scriptTask id="jsScriptTask" name="JS Script Task" scriptFormat="javascript" activiti:autoStoreVariables="false">
			<script>
				<!-- java.lang.System.out.println("Hello Websparrow.org"); -->
				var my = "Activiti is an open-source workflow engine.";
				print(my);
			</script>
		</scriptTask>
		<sequenceFlow id="flow1" sourceRef="startevent1" targetRef="jsScriptTask"></sequenceFlow>
		<endEvent id="endevent1" name="End"></endEvent>
		<sequenceFlow id="flow2" sourceRef="jsScriptTask" targetRef="endevent1"></sequenceFlow>
	</process>
</definitions>

The above BPMN process definition gives you the below-visualized diagram:

4.2 Execute it

package org.websparrow.activiti.controller;

import org.activiti.engine.RuntimeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/activiti")
public class ScriptTaskController {

	@Autowired
	private RuntimeService runtimeService;

	@GetMapping("script-task/js")
	public String jsScritTask() {

		runtimeService.startProcessInstanceByKey("js-script-task-process");

		return "check the console log...";
	}
}

Output: Hit the http://localhost:8080/activiti/script-task/js URL in your web browser and check your IDE console log. You will get the:

Activiti is an open-source workflow engine.

References

1. The Nashorn Java API
2. Java Scripting Programmer’s Guide
3. Script Task- Activiti User Guide