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74. Gemini Blueprint Compendium

The Gemini Blueprint implementation provides some useful extensions that SolarNode makes frequent use of. To use the extensions you need to declare the Gemini Blueprint Compendium namespace in your Blueprint XML file, like this:

Gemini Blueprint Compendium XML declaration
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:osgix="http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xsi:schemaLocation="
        http://www.osgi.org/xmlns/blueprint/v1.0.0
        http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium/gemini-blueprint-compendium.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

This example declares the Gemini Blueprint Compendium XML namespace prefix osgix and a related Spring Beans namespace prefix beans. You will see those used throughout SolarNode.

74.1 Managed Properties

Managed Properties provide a way to use the Configuration Admin service to manage user-configurable service properties. Conceptually it is like linking a class to a set of dynamic runtime Settings: Configuration Admin provides change event and persistence APIs for the settings, and the Managed Properties applies those settings to the linked service.

Imagine you have a service class MyService with a configurable property level. We can make that property a managed, persistable setting by adding a <osgix:managed-properties> element to our Blueprint XML, like this:

package com.example;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import net.solarnetwork.node.service.support.BaseIdentifiable;
import net.solarnetwork.settings.SettingSpecifier;
import net.solarnetwork.settings.SettingSpecifierProvider;
import net.solarnetwork.settings.SettingsChangeObserver;
import net.solarnetwork.settings.support.BasicTextFieldSettingSpecifier;

/**
 * My super-duper service.
 *
 * @author matt
 * @version 1.0
 */
public class MyService extends BaseIdentifiable
        implements SettingsChangeObserver, SettingSpecifierProvider {

    private int level;

    @Override
    public String getSettingUid() {
        return "com.example.MyService"; // (1)!
    }

    @Override
    public List<SettingSpecifier> getSettingSpecifiers() {
        return Collections.singletonList(
            new BasicTextFieldSettingSpecifier("level", String.valueOf(0)));
    }

    @Override
    public void configurationChanged(Map<String, Object> properties) {
        // the settings have changed; do something
    }

    public int getLevel() {
        return level;
    }

    public void setLevel(int level) {
        this.level = level;
    }

}
  1. The setting UID will be the Configuration Admin PID
title = Super-duper Service
desc = This service does it all.

level.key = Level
level.desc = This one goes to 11.

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:osgix="http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xsi:schemaLocation="
        http://www.osgi.org/xmlns/blueprint/v1.0.0
        http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium/gemini-blueprint-compendium.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <service>
        <interfaces>
            <value>net.solarnetwork.settings.SettingSpecifierProvider</value>
        </interfaces>
        <bean class="com.example.MyService"><!-- (1)! -->
            <osgix:managed-properties
                    persistent-id="com.example.MyService"
                    autowire-on-update="true"
                    update-method="configurationChanged"/>
            <property name="messageSource">
                <bean class="org.springframework.context.support.ResourceBundleMessageSource">
                    <property name="basenames" value="com.example.MyService"/>
                </bean>
            </property>
        </bean>
    </service>

</blueprint>
  1. You nest the <osgi:managed-properties> element within the actual service <bean> element you want to apply the managed settings on.
    • note how the persistent-id attribute value matches the getSettingsUid() value in MyService.java
    • the autowire-on-update method toggles having the Managed Properties automatically applied by Gemini Blueprint; you can set to false and provide an update-method if you want to handle changes yourself
    • the update-method attribute is optional; it provides a way for the service to be notified after the Configuration Admin settings have been applied.

When this plugin is deployed in SolarNode, the component will appear on the main Settings page and offer a configurable Level setting, like this:

Example service in Settings UI

74.2 Managed Service Factory

The Managed Service Factory service provide a way to use the Configuration Admin service to manage multiple copies of a user-configurable service's properties. Conceptually it is like linking a class to a set of dynamic runtime Settings, but you can create as many independent copies as you like. Configuration Admin provides change event and persistence APIs for the settings, and the Managed Service Factory applies those settings to each linked service instance.

Imagine you have a service class ManagedService with a configurable property level. We can make that property a factory of managed, persistable settings by adding a <osgix:managed-service-factory> element to our Blueprint XML, like this:

package com.example;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import net.solarnetwork.node.service.support.BaseIdentifiable;
import net.solarnetwork.settings.SettingSpecifier;
import net.solarnetwork.settings.SettingSpecifierProvider;
import net.solarnetwork.settings.SettingsChangeObserver;
import net.solarnetwork.settings.support.BasicTextFieldSettingSpecifier;

/**
 * My super-duper managed service.
 *
 * @author matt
 * @version 1.0
 */
public class ManagedService extends BaseIdentifiable
        implements SettingsChangeObserver, SettingSpecifierProvider {

    private int level;

    @Override
    public String getSettingUid() {
        return "com.example.ManagedService"; // (1)!
    }

    @Override
    public List<SettingSpecifier> getSettingSpecifiers() {
        return Collections.singletonList(
            new BasicTextFieldSettingSpecifier("level", String.valueOf(0)));
    }

    @Override
    public void configurationChanged(Map<String, Object> properties) {
        // the settings have changed; do something
    }

    public int getLevel() {
        return level;
    }

    public void setLevel(int level) {
        this.level = level;
    }

}
  1. The setting UID will be the Configuration Admin factory PID
title = Super-duper Managed Service
desc = This managed service does it all.

level.key = Level
level.desc = This one goes to 11.

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:osgix="http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xsi:schemaLocation="
        http://www.osgi.org/xmlns/blueprint/v1.0.0
        http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium
        http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium/gemini-blueprint-compendium.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basenames" value="com.example.ManagedService"/>
    </bean>

    <service interface="net.solarnetwork.settings.SettingSpecifierProviderFactory"><!-- (1)! -->
        <bean class="net.solarnetwork.settings.support.BasicSettingSpecifierProviderFactory">
            <property name="displayName" value="Super-duper Managed Service"/>
            <property name="factoryUid" value="com.example.ManagedService"/><!-- (2)! -->
            <property name="messageSource" ref="messageSource"/>
        </bean>
    </service>

    <osgix:managed-service-factory
            factory-pid="com.example.ManagedService"
            autowire-on-update="true"
            update-method="configurationChanged"><!-- (3)! -->
        <osgix:interfaces>
            <beans:value>net.solarnetwork.settings.SettingSpecifierProvider</beans:value>
        </osgix:interfaces>
        <osgix:service-properties>
            <beans:entry key="settingPid" value="com.example.ManagedService"/>
        </osgix:service-properties>
        <bean class="com.example.ManagedService">
            <property name="messageSource" ref="messageSource"/>
        </bean>
    </osgix:managed-service-factory>

</blueprint>
  1. The SettingSpecifierProviderFactory service is what makes the managed service factory appear as a component in the SolarNode Settings UI.
  2. The factoryUid defines the Configuration Admin factory PID and the Settings UID.
  3. You add a <osgix:managed-service-factory> element in your Blueprint XML, with a nested <bean> "template" within it. The template bean will be instantiated for each service instance instantiated by the Managed Service Factory.
    • note how the factory-pid attribute value matches the getSettingsUid() value in ManagedService.java and the factoryUid declared in #2.
    • the autowire-on-update method toggles having the Managed Properties automatically applied by Gemini Blueprint; you can set to false and provide an update-method if you want to handle changes yourself
    • the update-method attribute is optional; it provides a way for the service to be notified after the Configuration Admin settings have been applied.

When this plugin is deployed in SolarNode, the managed component will appear on the main Settings page like this:

Example managed service component in Settings UI

After clicking on the Manage button next to this component, the Settings UI allows you to create any number of instances of the component, each with their own setting values. Here is a screen shot showing two instances having been created:

Example managed service component intances in Settings UI