OSGi Blueprint Services

OSGi Blueprint Services

Blueprint Services

DI brought to OSGi

Guillaume Nodet


Author
• Guillaume Nodet
• ASF Member, VP Apache ServiceMix,
PMC member of various Apache
projects (ServiceMix, Felix, Geronimo,
Mina …)
• Software Architect at Progress Software
• OSGi Enterprise Expert Group

OSGi DevCon, June 22, 2009 Copyright Guillaume Nodet, Licensed under ASL 2.0 1


Agenda
• Introduction
• Configuration
• Beans
• Service references
• Service registrations
• Advanced uses
• Next steps
• Conclusion



Introduction
• Dependency injection / IOC
• Handle legacy code
• Handle the OSGi dynamics
• Hide the OSGi API



Configuration
• Extender pattern
• XML resources
• Metadata

Blueprint Bundle Metadata
XML

Blueprint Extender



Blueprint XML definition

blueprint ::= <type-converters> manager *
manager ::= <bean> | <service> | service-reference
service-reference ::= <reference> | <ref-list>
type-converter ::= <bean> | <ref>



Simple example

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0”>
<service interface=“osgi.devcon.User”>
<bean class=“osgi.devcon.impl.UserImpl”>
<argument value=“gnodet” />
</bean>
</service>
</blueprint>

bundleContext.registerService(
osgi.devcon.User.class.getName(),
new osgi.devcon.impl.UserImpl(“gnodet”),
new Hashtable());



Simple example

</bean>
</service>
</blueprint> Top level element

new Hashtable());



Simple example

</bean>
</service>
</blueprint> Blueprint namespace

new Hashtable());



Simple example

</bean>
</service>
</blueprint> Manager definition

new Hashtable());



Manager types
• Bean
• Single Service
Reference
• Multiple Service
References
• Service
Registration



Managers
• Described by some metadata
• Provide objects
• Activation / deactivation
• Dependencies (implicit or explicit)
• Initialization
– Eager
– Lazy
• Id
• Inlined managers


Bean manager

<argument value=”gnodet” />
<property name=“arrival” value=“22/06/09” />
</bean>



Bean creation
• Constructor creation
<bean class=“osgi.devcon.impl.UserImpl” />

new osgi.devcon.impl.UserImpl()

• Constructor creation with arguments
</bean>

new osgi.devcon.impl.UserImpl(“gnodet”)



Bean creation
• Static factory
<bean class=“osgi.devcon.impl.UserFactory”
factory-method=“createUser”>
</bean>

osgi.devcon.impl.UserFactory
.createUser( “gnodet”)



Bean creation
• Instance factory
<bean factory-ref=“userFactory”
factory-method=“createUser”>
</bean>

osgi.devcon.impl.UserFactory userFactory = …
userFactory.createUser( “gnodet”)



Bean arguments

<argument value=“gnodet”/>

<argument ref=“[refid]”/>

<argument>
[any value]
</argument>



Bean arguments



<argument>
[any value]
</argument> Plain value



Bean arguments



<argument>
[any value]
</argument>
Reference to a top
level manager



Bean arguments



<argument>
[any value]
</argument>
Complex value



Bean properties

<property name=“userId” value=“gnodet” />
</bean>

UserImpl user = new osgi.devcon.impl.UserImpl();
user.setUserId(“gnodet”);



Bean properties

</bean>


Property name



Bean properties

</bean>


Property value



Bean properties

<property name=“userId” value=“gnodet”/>

<property name=“userId” ref=“[refid]”/>

<property name=“userId”>
[any value]
</property>



Bean scope

• Singleton
– a single instance will be reused
• Prototype
– a new instance will be created each time it
is injected



Values
• <null/> • <value>
• <bean> • <list>
• <reference> • <set>
• <ref-list> • <map>
• <service> • <array>
• <ref> • <props>
• <idref>



<ref />
• Injects an object provided by the
manager with the given id
<bean id=“regId” … />

<property name=“registration”>
<ref component-id=“regId” />
</property>
</bean>

<property name=“registration” ref=“regId” />
</bean>



<ref />
• Injects an object provided by the
manager with the given id
Property value

<property name=“registration”>
<ref component-id=“regId” />
</property>
</bean>

<property name=“registration” ref=“regId” />
</bean>



<idref />
• Injects the id of an existing object


<property name=“registrationId”>
<idref component-id=“regId” />
</property>
</bean>



<value>
• Insert the content of the element text

<property name=“userId”>
<value>gnodet</value>
</property>
</bean>

</bean>



<list>, <set> and <array>
• Inserts a collection of objects

<list>
<list>
<value>2</value>
<value>7</value> Arrays.asList(
</list> Arrays.asList(“2”,”7”),
<list value-type=“int”> Arrays.asList(9,5)
<value>9</value> )
<value>5</value>
</list>
</list>



<list>, <set> and <array>
• Inserts a collection of objects

<list>
<list>
<value>2</value>
<value>7</value> Arrays.asList(
</list> Arrays.asList(“2”,”7”),
<list value-type=“int”> Arrays.asList(9,5)
<value>9</value> )
<value>5</value>
</list>
</list>

Type of the values



<map>
• Inserts a map of objects
<map>
<entry key="cheese" value="cheddar"/>
<entry key="fruit" value="orange"/>
</map>

<map>
<entry key-ref="keyId" value="cheddar"/>
<entry key="fruit" value-ref="valueId"/>
</map>

<map key-type=”...” value-type="... ">
<entry ...>
</map>



<map>
• Inserts a map of objects
<map>
<entry>
<key>
<value type="org.osgi.framework.Version">
3.2.1
</value>
</key>
<bean ... />
</entry>
</map>



<props>
• Inserts a java.util.Properties object

<props>
<prop key="1">one</prop>
<prop key="2" value="two" />
</props>



Components as values
• Instances provided by managers can be
injected

<list>
<bean class="com.acme.FooImpl"/>
</list>



Service References
• Single service: <reference>
• Multiple services: <ref-list>

<reference id="user1"
interface="osgi.devcon.User"
filter="(name=gnodet)" />

<ref-list id=”all-users"
interface="osgi.devcon.User” />



<reference>
• Provides a proxy to an OSGi service
• Availability: mandatory or optional
• Timeout
• Damping

proxy

backing
service

injected beans services service providers



<ref-list>
• Provides a read-only and dynamic list of
OSGi service
• Availability: mandatory or optional

backing
service

list

injected beans proxies services service providers



Service References Listeners
<bean id="listener" ... />

<ref-list interface="osgi.devcon.User">
<reference-listener ref="listener"
bind-method="bind"
unbind-method="unbind" />
</ref-list>

public class Listener {
public void bind(User user) { }
public void unbind(User user) { }
}

public void (T)
public void (T, Map)
public void (ServiceReference)



Service References Listeners

<ref-list interface="osgi.devcon.User">
<reference-listener ref="listener"
bind-method="bind"
unbind-method="unbind" />
</ref-list>

Bind method
public void bind(User user) { }
public void unbind(User user) { }
}

public void (T)
public void (ServiceReference)



Service registrations
• Expose an object as an OSGi service
• Register a ServiceFactory
• Dependencies on service references

<service ref="user"
interface="osgi.devcon.User" />

<service auto-export="interfaces">
<bean class="osgi.devcon.impl.UserImpl” />
</service>



Service properties
• Expose an object as an OSGi service

<service ref="fooImpl" interface="osgi.devcon.User">
<service-properties>
<entry key="name" value="gnodet"/>
</service-properties>
</service>



Service Registration Listeners

<service ref="..." interface="osgi.devcon.User">
<registration-listener
ref="listener"
registration-method="register"
unregistration-method="unregister" />
</ref-list>

public void register(User user, Map props) { }
public void unregister(User user, Map props) { }
}




Lifecycle



Lifecycle
Support for lazy
activattion



Lifecycle
Track mandatory
references



Lifecycle



Advanced use
• Conversions
• Disambiguation
• Creating custom converters
• Use of <idref>
• <ref-list> can be injected as
List<ServiceReference>
• Use of the ranking attribute on
<service>
• Blueprint Events



Conversions
• Arrays, collections, maps
• Primitives / wrapped primitives
• Simple types with a String constructor
• Locale, Pattern, Properties, Class
• JDK 5 Generics
• Custom converters



Disambiguation
• Constructors / factory methods can
have multiple overloads
public class Bar {
public Bar(File file) { ... }
public Bar(URI uri) { ... }
}

<bean class="foo.Bar">
<argument type="java.net.URI"
value="file://hello.txt"/>
</bean>



Custom converters
<type-converters>
<bean id="converter1" class=”foo.DateTypeConverter">
<property name="format" value="yyyy.MM.dd"/>
</bean>
</type-converters>

<bean class=“...”>
<property name=“date” value=“2009.06.22” />
</bean>

public class DateTypeConverter {
public boolean canConvert(Object fromValue,
CollapsedType toType) {
...
}
public Object convert(Object fromValue,
CollapsedType toType) throws Exception {
...
}
}



<ref-list> as

<ref-list interface=“osgi.devcon.User”
member-type=“service-reference” />



Other advanced uses
• <ref-list> as
<ref-list interface=“osgi.devcon.User”
member-type=“service-reference” />

• Use of ranking attribute on
<service>
<service ref=“foo”
interface=“osgi.devcon.User”
ranking=“5” />



Use of <idref>
• Prototypes
• Use of the Blueprint API
<bean id=“bar” class=“foo.Bar” scope=“prototype”>
<property name=“prop” value=“val” />
</bean>

<bean class=“foo.BarCreator”>
<property name=“blueprintContainer” ref=“blueprintContainer” />
<property name=“id”>
<idref component-id=“bar” />
</property>
</bean>

Bar bar = (Bar) blueprintContainer.getComponent(id)



Blueprint events
• Register listeners
• Blueprint events
– CREATING
– CREATED
– DESTROYING
– DESTROYED
– FAILURE
– GRACE_PERIOD
– WAITING

public interface BlueprintListener {
void blueprintEvent(BlueprintEvent event);
}



Next steps
• Custom namespace handlers
• Config Admin support



Custom namespaces
<ext:property-placeholder system-properties=“override”>
<ext:default-properties>
<ext:property name=“name” value=“value” />
</ext:default-properties>
</ext:property>

<bean ...>
<property name=“prop” value=“${name}” />
</bean>

<reference interface=“foo.Bar”
ext:proxy-method=“classes” />



Config Admin
• Injection of values from a Configuration

<cm:property-placeholder persistent-id=“foo.bar” />
<cm:default-properties>
<cm:property name=“name” value=“value” />
</cm:default-properties>
</cm:property>

<bean ...>
<property name=“prop” value=“${name}” />
</bean>



Config Admin
• Support for managed properties

<bean class=“foo.Bar”>
<cm:managed-properties
persistent-id=“foo.bar”
updated-strategy=“component-managed”
update-method=“update” />
</bean>



Config Admin
• Support for managed service factories

<cm:managed-service-factory
factory-pid=“foo.bar”
interface=“foo.Bar”>
<service-properties>
<entry key=“key1” value=“value1” />
</service-properties>
<cm:managed-component class=“foo.BarImpl” />
</bean>



Implementations
• Spring-DM (RI)
– Based on the Spring Framework
– > 2 Mo but provide more features
• Geronimo blueprint
– Clean implementation of Blueprint
– Size < 300 Ko
– Integrated in Apache Felix Karaf



Conclusion
• Existing alternatives
– DS, iPojo, Peaberry
• Strengths of blueprint
– Familiarity with Spring
– More powerful Dependency Injection
– Easily extensible through namespaces

gnodet@gmail.com
http://svn.apache.org/repos/asf/geronimo/sandbox/blueprint


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