Apache Karaf Scheduler example

Abstract

This example shows you how to create a runnable service periodically executed by the Apache Karaf scheduler.

More than executing periodically shell commands, the Karaf Scheduler uses whiteboard pattern to automatically schedule runnable services.

In this example, we will register a Runnable service displaying a message in the shell console. As service properties, we add details for the scheduler to periodically call our service.

Artifacts

karaf-scheduler-example-runnable is the core Runnable service with the scheduler details.
karaf-scheduler-example-features contains features used for deployment.

Build

The build uses Apache Maven. Simply use:

mvn clean install

## Features & Deployment

On a running Karaf instance, register the features repository using:

karaf@root()> feature:repo-add mvn:org.apache.karaf.examples/karaf-scheduler-example-features/LATEST/xml

Then, you can install the runnable service feature:

karaf@root()> feature:install karaf-scheduler-example

## Usage

Once you have installed the runnable feature, you will periodically see this kind of message in the shell console:

Hello Karaf User !

You can see the task in the Karaf scheduler using the scheduler:list command:

karaf@root()> scheduler:list 
Name        │ Schedule
────────────┼──────────────────────────────────────────
example.116 │ at(2018-02-19T11:07:24.829+01:00, -1, 10)