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Inter module communication in DX 7.2 using OSGiWednesday 22th, 2017

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Introduction

What will you see?Some slides about OSGi Some code of DX bundlesPeople talking

There are 29 slides

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Use Services to communicate between

modules.

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1 What kind of service?

- Spring services

- OSGi services

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1 What are OSGi Services?

Definition:An Interface (service interface) with its implementation registered in the OSGi service registry

An OSGi service can be:- Started- Stopped- Configured- Called from anywhere

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Get a service from DX.

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2 How services are exposed by DX

- Spring beans- OSGi services (since

7.2)

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2 Sample of available services

- Site service- Publication service- Categories service- Mail Service

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2 How to get Services

Spring injection

<bean id="myBean" class="org.jahia.modules.Myclass" > <property name="jcrStoreService" ref="JCRStoreService"/></bean>

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2 How to get Services

Blueprint

<osgi:reference id="myService" interface="org.jahia.modules.MyServiceInterface"

/>

<bean id="myBean" class="org.jahia.modules.Myclass" > <property name="myService" ref="myService"/></bean>

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2 How to get Services

OSGi Annotations @Component(...)public class MyClass implements MyInterface {...@Reference(service = MyService.class)protected void bindMyService(MyService myService) { this.myService = myService;}private MyService myService;

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2 How to get Services

DEMO

A DX module that uses the mail service to send a mail on a submitted form

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Create and expose Services

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3 Create and Expose service

Using blueprint

<osgi:service interface="org.jahia.myService"> <osgi:service-properties> <entry key="Service Description" value="my OSGi Service"/> <entry key="Service Vendor" value="Jahia Solutions Group SA"/> </osgi:service-properties> <bean class="org.jahia.myServiceImpl"/></osgi:service>

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3 Expose service

Using OSGi annotation

@Component(name = "org.jahia.myService", service = MyService.class, property = { Constants.SERVICE_PID + "=org.jahia.myService", Constants.SERVICE_DESCRIPTION + "=my OSGi Service", Constants.SERVICE_VENDOR + "=" + Jahia.VENDOR_NAME}, immediate = true)public class MyServiceImpl implements MyService{

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3 Expose service

DEMOModule that exposes a Mail Template service. This service provides methods to wrap the mail content before sending it.

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4Consume an OSGi service from another module

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Consume OSGi service

Same as DX service, using OGSi reference.

Can be done using blueprint or annotations

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Consume OSGi service

Handle import export.

- Export the Interface package to expose the service

- Import is done by the maven-bundle-plugin while building the module.

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Consume OSGi service

Demo

Use the Template Mail service in the send mail module instead of DX mail service.

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5Advanced concepts

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List of services that match an interface

OSGi list, is a blueprint mechanism.

- Provides a dynamic list of services that match an interface.

- The list is automatically updated on service availability

DEMO

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Services listeners

Service tracker:Can be set to perform operations on service add /

remove or modified on a filtered list of services.

Service listener:All events related to services can be catch to

execute custom code

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Other way of communication

Activators:Atcs at bundle startup, can register listener that will

react on other bundle activation.

OSGi Listeners:This allows to react on bundle states change

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Tools

- OSGi web console

- Karaf shell

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Conclusion

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Mix the things

Use OSGi services instead of Spring bean injection

OSGi services have been designed for that purpose.

It solves a lot of Spring injection issue:- Class loading- Module order startup and dependencies

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Mix the things

Sources of the modules are available here:https://github.com/Jahia/inter-module-communication-demo

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THE END!THANKS FOR LISTENING