Lab 1 Introduction ipojo Component Model

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1 Lab 1 Introduction ipojo Component Model Thomas Leveque A Page 1, January 27, 2011

2 Service Oriented Computation New computing paradigm Service as fundamental element Reduce dependencies among «software islands» Separate evolution of different pieces More flexible than monolithic approach SOC technologies today Jini, Web Services, OSGi, UPnP, DPWS Page 2, January 27, 2011

3 Service Oriented Architecture Service Broker Lookup S1 reference S1 Service Specification Publication Service Consumer Bind & Invoke S1 Service Provider Page 3, January 27, 2011

4 Dynamic Service Oriented Architecture Service Broker Lookup New S1 reference Notification Notification Service Consumer S1 Service Provider 1 S1 Service Provider 2 Page 4, January 27, 2011

5 Service Oriented Computation Advantages Loose coupling Late binding (at runtime) Hide heterogeneity Drawbacks Dynamics in nature Dynamics is very difficult to manage Page 5, January 27, 2011

6 Component Model Separation of concerns Avoid the mix between business code and non functional concerns. Avoid monolithic application An assembler uses (existing) components and put them together Page 6, January 27, 2011

7 Service Oriented Component Model Combine advantages of components based software engineering (CBSE) and service oriented computing (SOC) A component Provides services Uses services Component A S1 S2 requires service S1 provides service S2 Page 7, January 27, 2011

8 ipojo ipojo is a service component model Plain Old Java Object (POJO) Simple Java class containing the business logic For dynamic environment Extensible and Flexible Aims to ease the application development on the OSGi framework Hide non functional concerns inside the implementation Hide service interactions Manage dynamics Page 8, January 27, 2011

9 ipojo Architecture S1 Component 2 Component 1 S2 Component 3 ipojo OSGi (Felix) JVM Page 9, January 27, 2011

10 ipojo Component Component Type Define provided and required services Define other properties such as component starting/stopping Component Instance Has a name Multiple component instances of the same component type could be created and executed Component Type / Component Instance is similar to Class / Object Page 10, January 27, 2011

11 ipojo Component Type A Java Java annotation * Service * 1 Service Specification Service Providing +property[*] provides requires Service Dependency +query Component A Java Java annotation Page 11, January 27, 2011

12 ipojo Component Definition Add Java to a Java class Provides a Service Implements a Java interface (= service specification) Add MyServiceImplementation MyService provides MyService Page 12, January 27, 2011

13 ipojo Component Definition Requires a Service Add a Java field (field type must be corresponding service interface) Add to the field MyServiceConsumer MyService requires MyService Page 13, January 27, 2011

14 ipojo Component Instance Definition Add Java to a Component Java class A default name is generated (<component name>-0) Set name parameter value to define the instance name You can also define instances using the metada.xml file (but it is more complex) Page 14, January 27, 2011

15 ipojo Component Instance Lifecycle Automatically started and stopped by ipojo method method Page 15, January 27, 2011

16 How does it work? ipojo add code to your component classes during compilation time bytecode modification performed after Java compilation Annotations POJO POJO POJO Meta information in Manifest file POJO POJO ipojo Page 16, January 27, 2011

ipojo Application Launch All instances are created

start the OSGi platform Bindings are automatically

Inst1: AudioPlayer AudioCodec AudioCodec Inst3:

17 ipojo Application Launch All instances are created and started in the right order by ipojo when you start the OSGi platform Bindings are automatically defined by ipojo Speaker Inst2: InternalSpeaker Inst1: AudioPlayer AudioCodec AudioCodec Inst3: MP3Codec Inst4: WMACodec ipojo + Felix Page 17, January 27, 2011

18 ipojo Component Instance Debug Use instances command to list component instances Use instance <instance name> command to check component instance state Page 18, January 27, 2011

19 Felix/iPojo Useful Commands factories List all component types (= factories) lb List all deployment units stop 0 Shutdown the program Workaround for an Eclipse bug: Use lb command after launching your application in order to be sure that your component instances have been created. Page 19, January 27, 2011

20 Questions? Page 20, January 27, 2011

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