Declarative Services Dependency Injection OSGi style Felix Meschberger Day Management AG [email_address] Zurich, September 22 nd 2009

About Felix Meschberger Senior Developer at Day Management AG [email_address] http://blog.meschberger.ch OSGi Implementations @ Apache Felix Declarative Services Configuration Admin Metatype Service

Senior Developer at Day Management AG

[email_address]

http://blog.meschberger.ch

OSGi Implementations @ Apache Felix

Declarative Services

Configuration Admin

Metatype Service

Contents Dependency Injection Implementations for OSGi Declarative Services Issues Maven SCR Plugin Declarative Services 1.1

Dependency Injection

Implementations for OSGi

Declarative Services

Issues

Maven SCR Plugin

Declarative Services 1.1

Dependency Injection Loose Coupling „ Don't call use, we'll call you“ Easier Testing Inject different implementations Popular in Spring Framework Traditionally Descriptor Based Current Trend: Java Annotations

Loose Coupling

„ Don't call use, we'll call you“

Easier Testing

Inject different implementations

Popular in Spring Framework

Traditionally Descriptor Based

Current Trend: Java Annotations

Implementations for OSGi Declarative Services iPOJO (Evolution of Declarative Services) Spring DM Blueprint Service (Evolution of Spring DM) Peaberry (based on Google Guice) … possibly more …

Declarative Services

iPOJO (Evolution of Declarative Services)

Spring DM

Blueprint Service (Evolution of Spring DM)

Peaberry (based on Google Guice)

… possibly more …

Declarative Services Version 1.0 Part of Compendium Services since R4 XML Descriptor Based Lifecycle Management Dependency Injection (Services) Configuration Support

Version 1.0

Part of Compendium Services since R4

XML Descriptor Based

Lifecycle Management

Dependency Injection (Services)

Configuration Support

Component Descriptor XML Descriptors may be embedded Namespace for Component http://www.osgi.org/xmlns/scr/v1.0.0 Descriptors listed in Bundle Manifest Header Service-Component Multiple Components per Document

XML

Descriptors may be embedded

Namespace for Component

http://www.osgi.org/xmlns/scr/v1.0.0

Descriptors listed in Bundle Manifest Header

Service-Component

Multiple Components per Document

Component Descriptor <scr:component name=“sample.component“ xmlns:scr=“...“> <implementation class=“org.sample.component“ /> <reference interface=“org.osgi.service.log.LogService“ bind=“bindLog unbind=“unbindLoad“ /> <property name=“p1“ value=“sample“ /> <property name=“p2“ type=“Integer“> 1 2 </property> </component>

Lifecycle Management Load Descriptors on Bundle Start Instantiation Configuration Activation Dependency Injection Deactivation Unload on Bundle Stop

Load Descriptors on Bundle Start

Instantiation

Configuration

Activation

Dependency Injection

Deactivation

Unload on Bundle Stop

Component Descriptor <scr:component name=“sample.component“ xmlns:scr=“...“> <implementation class=“org.sample.component“ /> <reference interface=“org.osgi.service.log.LogService“ bind=“bindLog unbind=“unbindLoad“ /> <property name=“p1“ value=“sample“ /> <property name=“p2“ type=“Integer“> 1 2 </property> </component>

Lifecycle Sample: Activation package org.sample; public class Component { protected void activate ( ComponentContext c) { System.out.println(„Activating“); } protected void deactivate ( ComponentContext c) { System.out.println(„Deactivating“); } }

Lifecycle Sample: Binding package org.sample; public class Component { protected void bindLog ( LogService ls) { this.logService = ls } protected void unbindLog ( LogService ls) { this.logService = null; } }

Lifecycle Sample: Configuration package org.sample; public class Component { protected void activate ( ComponentContext c) { Dictionary props = c .getProperties() ; String p1 = (String) props.get(„p1“); int[] p2 = (int[]) props.get(„p2“); } }

Component Types Regular Component (non-service) Service Service Factory Component Factory

Regular Component (non-service)

Service

Service Factory

Component Factory

Dependency Injection Event-based using bind/unbind methods Lookup oriented using ComponentContext Optionality Multiplicity Binding Policy

Event-based using bind/unbind methods

Lookup oriented using ComponentContext

Optionality

Multiplicity

Binding Policy

Configuration Configuration from Configuration Admin Properties from Descriptor Provided through ComponentContext.getProperties()

Configuration from Configuration Admin

Properties from Descriptor

Provided through ComponentContext.getProperties()

Instantiation (non Factory) If Enabled and Satisfied Single Instance No Configuration Singleton Configuration ( service.pid ) Multiple Instances Factory Configuration ( service.factoryPid )

If Enabled and Satisfied

Single Instance

No Configuration

Singleton Configuration ( service.pid )

Multiple Instances

Factory Configuration ( service.factoryPid )

Instantiation (Component Factory) ComponentFactory.newInstance() ComponentInstance.dispose() Controlled by Application Only Configuration may not be Factory Configuration

ComponentFactory.newInstance()

ComponentInstance.dispose()

Controlled by Application Only

Configuration may not be Factory Configuration

Descriptor Unvealed: Component <scr:component name= enabled= immediate= factory= configuration-policy= activate= deactivate= > … Component Description … </scr:component>

</scr:component>

Descriptor Unvealed: Implementation <implementation class= />

Descriptor Unvealed: Property <property name= value= type= /> <property name= type= > … values … </property>

Descriptor Unvealed: Properties <properties entry= />

Descriptor Unvealed: Service <service servicefactory= > <provide interface= /> … More Provide Elements … </service>

Descriptor Unvealed: Reference <reference name= interface= cardinality= policy= target= bind= unbind= />

Issue: Configuration Data Types Wrapper of primitive types Byte, Short, Integer, Long, etc. String Array or Vector Primitive types Wrappers of primitive types String

Wrapper of primitive types

Byte, Short, Integer, Long, etc.

String

Array or Vector

Primitive types

Wrappers of primitive types

String

Issue: XML Descriptor Good to re-use legacy POJO Problematic to keep in-sync with DS Classes YAXF – Yet another XML File

Good to re-use legacy POJO

Problematic to keep in-sync with DS Classes

YAXF – Yet another XML File

Maven SCR Plugin Generates Descriptors from Java Source JavaDoc tags @scr.component, @scr.property, ... Java Annotations @Component, @Property, ... High Level Annotations @SlingServlet

Generates Descriptors from Java Source

JavaDoc tags

@scr.component, @scr.property, ...

Java Annotations

@Component, @Property, ...

High Level Annotations

@SlingServlet

Issue: Not really POJO Requires OSGi API for full functionality Activate and Deactivate method names fixed Configuration through ComponentContext Service properties through ServiceReference Fixed in Declarative Services 1.1

Requires OSGi API for full functionality

Activate and Deactivate method names fixed

Configuration through ComponentContext

Service properties through ServiceReference

Fixed in Declarative Services 1.1

Declarative Services 1.1 Scheduled for OSGi R 4.2 Configurable names for (de)activator methods More (de)activator method arguments ComponentContext BundleContext Map int/Integer (deactivator only) Any combination

Scheduled for OSGi R 4.2

Configurable names for (de)activator methods

More (de)activator method arguments

ComponentContext

BundleContext

Map

int/Integer (deactivator only)

Any combination

Declarative Services 1.1 (cont.) More (un)bind method arguments ServiceReference Service instance Service instance and Map Configuration Dependency Optional Ignore Require Support for private properties

More (un)bind method arguments

ServiceReference

Service instance

Service instance and Map

Configuration Dependency

Optional

Ignore

Require

Support for private properties

Declarative Services 1.1 (cont.) Activator and bind methods may be public (discouraged) protected private (if in the component class) default (if in the same package) Wildcards for Service-Component header

Activator and bind methods may be

public (discouraged)

protected

private (if in the component class)

default (if in the same package)

Wildcards for Service-Component header

Questions

Thank You!