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Schedule a Java Service in WaveMaker

Overview​

WaveMaker lets you run backend Java logic automatically at defined time intervals using Spring Scheduler. This guide walks you through creating a schedulable Java Service, configuring it as a Spring bean, and setting a cron expression to control when it runs.

Create a Java Service​

  1. In your WaveMaker project, navigate to File Explorer > src/main/java and open or create your Java Service class.
  2. Define the method you want to schedule. The method must be public and return void or a serializable type.
package com.example.simplejavaservice;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.wavemaker.runtime.service.annotations.ExposeToClient;

@ExposeToClient
public class SimpleJavaService {

    private static final Logger logger = LoggerFactory.getLogger(SimpleJavaService.class);

    public String sampleJavaOperation() {
        logger.warn("Starting sample operation");
        String result = "HELLO SERVICE!";
        logger.warn("Returning {}", result);
        return result;
    }
}

Configure Spring Scheduler​

  1. Open project-user-spring.xml from File Explorer > src/main/webapp/WEB-INF/.
  2. Add the Spring task namespace to the <beans> declaration.
  3. Register your Java Service as a Spring bean and define the scheduled task:
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:task="http://www.springframework.org/schema/task"
       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
           http://www.springframework.org/schema/task
           http://www.springframework.org/schema/task/spring-task.xsd">

    <bean id="SimpleJavaService"
          class="com.example.simplejavaservice.SimpleJavaService"
          scope="singleton"
          lazy-init="true" />

    <task:scheduled-tasks>
        <task:scheduled
            ref="SimpleJavaService"
            method="sampleJavaOperation"
            cron="*/10 * * * * ?" />
    </task:scheduled-tasks>

</beans>
note

The ref value must match the id of the bean you defined. The method value must exactly match the method name in your Java Service class.

Enable the Scheduler​

Add the following lines inside the same <beans> block to activate Spring's scheduling engine:

<task:annotation-driven scheduler="taskScheduler"/>
<task:scheduler id="taskScheduler" pool-size="5"/>

Adjust pool-size based on how many concurrent scheduled tasks your application needs.

Understanding Cron Expressions​

Spring Scheduler uses a six-field cron format:

Seconds   Minutes   Hours   Day-of-Month   Month   Day-of-Week
ExampleMeaning
*/10 * * * * ?Every 10 seconds
0 */5 * * * ?Every 5 minutes
0 0 9 * * MON-FRIEvery weekday at 9:00 AM
0 0 0 1 * ?First day of every month at midnight

Schedule Multiple Services​

To schedule more than one service, register each as a bean and add separate <task:scheduled-tasks> blocks:

<bean id="ServiceOne" class="com.example.ServiceOne"/>
<bean id="ServiceTwo" class="com.example.ServiceTwo"/>

<task:scheduled-tasks>
    <task:scheduled ref="ServiceOne" method="methodOne" cron="*/10 * * * * ?" />
</task:scheduled-tasks>

<task:scheduled-tasks>
    <task:scheduled ref="ServiceTwo" method="methodTwo" cron="*/20 * * * * ?" />
</task:scheduled-tasks>

Conclusion​

You have successfully configured a Java Service to run on a schedule using Spring Scheduler in WaveMaker. With cron expressions, you can control execution timing precisely — from every few seconds to monthly jobs. As your application grows, you can register additional beans and extend the scheduler to handle multiple background tasks independently.

See Also​