# 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) ```