Creating a New JOnAS Service

A JOnAS service is represented by a class that implements its service interface and extends the class org.ow2.jonas.lib.service.AbsServiceImpl, and thus must implement at least the following methods:

These methods will be called by JOnAS for starting and stopping the service.

The service interface should look like the following:

package a.b.myservice;

public interface MyServiceInterface {
    void doSomething();
}

The service class should look like the following:

package a.b.myservice.internal;

import a.b.myservice.MyServiceInterface;

import org.ow2.jonas.lib.service.AbsServiceImpl;
import org.ow2.jonas.service.ServiceException;

.....

public class MyService extends AbsServiceImpl implements MyServiceInterface {
    private String property;

    public void doStart() throws ServiceException {
        ....
    }

    public void doStop() throws ServiceException {
        ....
    }

    public void doSomething() {
        ....
    }

    public String getProperty() {
        return property;
    }

    public void setProperty1(final String property) {
        this.property1 = property;
    }
}

A JOnAS service must be packaged in an OSGi bundle in order to be deployed on the JOnAS OSGi platform. It implies to create a standard packaging structure. An OSGi bundle is like a classic JAR file plus a specific MANIFEST file. To make easier the service creation, configuration and management of possible dependencies with other JOnAS services, it is recommanded to use iPOJO to build your JOnAS services. This guide will present the iPOJO solution.

The JAR structure of the bundle must contain the following parts:

The OSGi MANIFEST should contain the following attributes:

Import-Package: org.ow2.jonas.lib.service, org.ow2.jonas.service, ...
Export-Package: a.b.myservice
Private-Package: a.b.myservice.internal
Bundle-Version: 5.1.0
Bundle-Name: MyService
Bundle-SymbolicName: a.b.myservice

If the project is built with Maven, it is possible to generate this file during the project compilation thanks to the maven-bundle-plugin. This plugin is based on the BND tool which can also be used separately.

The service is defined and its initialization parameters specified in the jonas.properties file. First, choose a name for the service (e.g. "serv1"), then do the following:

This is illustrated as follows:

jonas.services                  .......,serv1 
jonas.service.serv1.class       a.b.myservice.internal.MyService
jonas.service.serv1.property    value      

iPOJO is a Service Component Runtime aiming to simplify OSGi application development. You have to create the iPOJO component which will define your JOnAS service. This component must declare the provided and required services, the start and stop callback methods and the service properties.

The iPOJO metadata file should look like the following:

<?xml version="1.0" encoding="UTF-8"?>
<ipojo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="org.apache.felix.ipojo"
       xsi:schemaLocation="org.apache.felix.ipojo http://felix.apache.org/ipojo/schemas/1.2.0/core.xsd" >

  <component classname="a.b.myservice.internal.MyService"
             immediate="false">
    <provides specifications="a.b.myservice.MyServiceInterface" />

    <!-- Required dependencies -->
    <requires optional="false"
              specification="org.ow2.jonas.properties.ServerProperties">
      <callback type="bind" method="setServerProperties" />
    </requires>

    <!-- LifeCycle Callbacks -->
    <callback transition="validate" method="start" />
    <callback transition="invalidate" method="stop" />

    <properties propagation="true">
      <property name="property" method="setProperty" />
    </properties>
  </component>
</ipojo>

iPOJO component description

The existing JOnAS services are the following:

The org.ow2.jonas.service.ServiceException exception is defined for Services. Its type is java.lang.RuntimeException and it can encapsulate any java.lang.Throwable .