Post on 15-May-2015
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. JAX 2009
OSGi ServiceComponent Models
Heiko Seeberger (WeigleWilczek)Kai Tödter (Siemens Corporate Technology)
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
2
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Why Components?
3
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
The OO Dream
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"Object Oriented technology was going to change the world . . . we would have all these objects in our library and building a new system would be a snap. Just get a few classes,
bunch them together . . . and voila!"Peter Kriens, http://www.aqute.biz/Blog/2006-04-29
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
The OO Reality
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Coupling!
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• Classes can almost never be used in isolation
• They depend on other classes
• Those classes depend on other packages, which depend on other JARs . . .
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
How can Components help?
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Components ...
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• are self-contained and declare their dependencies
• declare their interface and hide their internals
• interact with the container and obey to a life cycle
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi enables Components
• OSGi Framework is the container
• Managed dependencies
• Life cycle and interactions with the container
• Loose coupling through service model
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Why Service Component Models?
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Why not use plain OSGi APIs?
• We want to avoid OSGi glue code
• POJOs enhance testability
• Repetitive glue code reduces productivity
• Service Component Models ease service handling
• OSGi APIs lead to involved code
• SCMs offer advanced features
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
12
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi Framework
Active Bundle
Component
Component Instance
Service
reference
Component Description
Active Bundle
Component
Component Description
Component Instance
provide
OSGi Declarative Services
13
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi Framework
DS-powered Bundle
Service ComponentRuntime
createComponent
Service Component Runtime
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Declaring a Component
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• Specify component description(s) via Service-Component manifest header
• Specify the implementation class
Service-Component: OSGI-INF/treeView.xml
<component xmlns="http://www.osgi.org/xmlns/scr/v1.1.0"> <implementation class="...TreeView"/></component>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Providing a Service
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• Specify each service interface
• By default components providing a service are delayed
<service> <provide interface="...IViewContribution"/> <provide interface="...IPersonListener"/></service>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Referencing Services
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• Specify the service interface
• Specify bind and unbind methods
• Specify the cardinality
<reference interface="...IPersonManager" bind="setPersonManager" unbind="removePersonManager" cardinality="1..1"/>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Concurrency for static and dynamic Policy
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• No concurrency issues for static policy
• On (un)binding of references the component is deactivated and activated again
• Pay attention to concurrency for dynamic policy
• The component must be thread-safe regarding references
<reference ... policy="dynamic"/>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
19
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi Framework
Active Bundle
Application Context
Bean
Service
import
Active Bundle
Application Context
Bean
exportBean
Bean
Bean
Spring Dynamic Modules
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi Framework
Spring-powered Bundle
Spring DM Extender
createApplication Context
Spring DM Extender
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Declaring a Bundle Application Context
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• By default configurations are looked up under META-INF/spring/
• Multiple configurations are merged into a single Application Context
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Providing a Service
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• Specify each service interface or use auto-export
• Beans exported as service cannot be lazy
<osgi:service ref="treeView" auto-export="interfaces" />
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Referencing Services
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• A local bean is created with given ID
• Specify the service interface
• Specify the cardinality
<osgi:reference id="personManagerOSGi" interface="...IPersonManager" cardinality="1..1">
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Concurrency in Spring DM
• References are only injected once
• Proxies for unary references
• Managed collections for multiple references with “Iterator guarantee”
• Concurrency issue is swapped for uncertainty
• ServiceUnavilableException
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
26
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
OSGi Framework
Active Bundle
Component
Component Instance
Service
reference
Component Metadata
Active Bundle
Component
Component Metadata
Component Instance
provide
Apache iPOJO
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© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Declaring a Component
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• Component metadata will be used to instrument the bytecode at build-time
• Specify component and instance
<ipojo> <component classname="...TreeView" /> <instance component="...TreeView" /></ipojo>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Providing a Service
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• Service interfaces are computed by iPOJO
• iPOJO services are created lazily
<component ...> <provides /></component>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Referencing Services
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• iPOJO offers field and method injection
<requires field="logService" /><requires> <callback type="bind" method="setPersonManager" /> <callback type="unbind" method="removePersonManager" /></requires>
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Concurrency in iPOJO
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• iPOJO manages concurrency for references
• We can write our code without regard for thread-safety
• Bytecode instrumentation weaves in all necessary synchronization
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
32
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Comparison
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DS DM iPOJO
POJO-ness + + +
DI power o + o
Ease of programming model o o +
Ease of build + + -
Size and dependencies + - +
Support for laziness + - +
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Agenda
• Why? What?
• OSGi Declarative Services
• Spring Dynamic Modules
• Apache iPOJO
• Guice Peaberry
• Comparison
• Demo
34
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
Dynamic Swing OSGi Demo
35
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.
OSGi Service Component Models
How to get the Demo?
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• http://max-server.myftp.org/trac/pm
• Wiki with some documentation
• Anonymous Subversion access
• Trac issue tracking
• Licenses
• All PM project sources are licensed under EPL
• Swing Application Framework (JSR 296) implementation is licensed under LGPL
• Swing Worker is licensed under LGPL
• The nice icons from FamFamFam are licensed under the Creative Commons Attribution 2.5 License.
© 2009 Seeberger, Tödter. Released under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. JAX 2009
Thank you!Slides at www.slideshare.net/heiko.seeberger/jax-09-osgi-service-components-models
Demo at max-server.myftp.org/trac/pm