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OSGi Remote Services with SCA using Apache Tuscany

OSGi Remote Services with SCA using Apache Tuscany. Raymond Feng rfeng@apache.org. Agenda. What are OSGi remote services? A sample scenario: Distributed Calculator Representing OSGi entities using SCA Predefined mapping from OSGi to SCA On-demand mapping from OSGi to SCA

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OSGi Remote Services with SCA using Apache Tuscany

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  1. OSGi Remote Services with SCA using Apache Tuscany Raymond Feng rfeng@apache.org

  2. Agenda • What are OSGi remote services? • A sample scenario: Distributed Calculator • Representing OSGi entities using SCA • Predefined mapping from OSGi to SCA • On-demand mapping from OSGi to SCA • Discovery of OSGi remote services • Demo of distributed calculator • Q&A

  3. What are OSGi remote services?

  4. OSGi local services • The OSGi framework decouples service providers and consumers via a localservice registry, where a service is an object that one bundle registers and another bundle gets. • The services are only be accessed locally by bundles within the same framework instance. It would be nice to make them remote without significant changes of the programming model?

  5. OSGi Remote Services • The OSGi core framework specifies a model where bundles can use distributed services. (R4.2) • The basic model for OSGi remote services is that a bundle can: • register services that are exported to a communication endpoint • use services that are imported from a communication endpoint (registering a proxy in local service registry)

  6. OSGi Remote Services NOTE: The diagram is copied from OSGi Service Platform Service Compendium R4.2 spec

  7. Related OSGi specs • OSGi Service Platform Release 4 Version 4.2 Compendium Specification • Chapter 13: Remote Services (PM, concepts and properties) • http://www.osgi.org/download/r4v42/r4.cmpn.pdf • Early Access draft of the OSGi 4.2 Enterprise Release • SCA Configuration Type (SCA specific properties) • Remote Service Admin (runtime architecture, SPIs) • http://www.osgi.org/download/osgi-4.2-enterprise-early-draft4.pdf

  8. SCA Configuration Type • SCA Configuration Type for Remote Services • This chapter provides a standard mechanism to configure Remote Services and provide qualities of service or intents, through SCA configuration metadata and WS-Policy. Remote Service implementations that also implement the SCA config type provide a portable way to configuration.

  9. Remote Service Admin • Remote Service Admin • This specification adds an extra layer on top of the existing Remote Services spec (chapter 13 in the 4.2 Compendium). • The Distribution Provider registers a RemoteServiceAdmin service that exports and imports services when asked. • The Discovery System API (EndpointListener) provides a standard view over any Discovery System, regardless of how it's realized or what protocol it uses. • The Topology Manager provides a Policy over these things. It decides what services will be exported and for when to look for services in a Discovery System.

  10. OSGi remote services- A sample scenario

  11. An OSGi based Calculator Add Service Subtract Service Calculator Service Multiply Service Divide Service Calculator bundle Operations Bundle Calculator Service OSGi service OSGi service interface OSGi service reference OSGi service implementation

  12. Making the Calculator Distributed • Run the calculator bundle and the operations bundle on two OSGi framework instances. • The calculator bundle registers the CalculatorService and it looks up the Add/Subtract/Multiply/Divide services (which are remote over RMI) from the service registry. The CalculatorService is exported as a Web Service. • The operations bundle registers four remote services (Add/Subtract/Multiply/Divide). These services are exported over RMI.

  13. RMI Add Service RMI Subtract Service Calculator Service Web Service RMI Multiply Service RMI Divide Service Calculator bundle Operations Bundle OSGi runtime #1 OSGi runtime #2 OSGi Remote Services enabled Calculator

  14. Modeling OSGi entities using SCA

  15. The Calculator Scenario: OSGi Remote Services with SCA runtime as the distribution software SCA Component implementation.osgi binding.rmi or binding.ws SCA Component implementation.osgi Add Service Subtract Service Multiply Service Calculator Service Divide Service OSGi bundle OSGi bundle SCA environment

  16. Defining the SCA composite for OSGi bundles OSGI-INF/sca/bundle.composite SCA bundle binding.rmi binding.ws Calculator Operations Add Service Subtract Service Calculator Service Multiply Service Divide Service Calculator bundle Operations Bundle

  17. SCA view of OSGi services and references Local Service OSGi Service Registry Local OSGi Service Implementation SCA Service Calculator Service Web Service Add Service RMI Subtract Service RMI Multiply Service RMI Divide Service RMI SCA References SCA proxies

  18. SCA implementation.osgi • The SCA implementation.osgi component will be used to encapsulate one or more OSGi bundles. • OSGi View: implementation.osgi provides the metadata and infrastructure to enable the distribution of OSGi services • SCA View: implementation.osgi allows OSGi bundles to participate in the SCA assembly. • The references for an SCA OSGi component represents the OSGi services to be consumed by the bundles • The services for an SCA OSgi component represents the OSGi services to be provided by the bundles

  19. Predefined mapping from OSGi to SCAhttp://svn.apache.org/repos/asf/tuscany/java/sca/samples/dosgi-calculator/http://svn.apache.org/repos/asf/tuscany/java/sca/samples/dosgi-calculator-operations/

  20. Mapping an OSGi bundle to an SCA componentType <componentType xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903" xmlns:t="http://tuscany.apache.org/xmlns/sca/1.1"> <!-- The service elment defines an SCA view of the OSGi service --> <service name="CalculatorService"> <!-- The interface will be mapped into the OSGi service class --> <interface.java interface="calculator.dosgi.CalculatorService"/> </service> <!-- The reference elment defines an SCA proxy to a remote OSGi service --> <reference name="addService"> <interface.java interface="calculator.dosgi.operations.AddService"/> </reference> <reference name="subtractService"> <interface.java interface="calculator.dosgi.operations.SubtractService"/> </reference> <reference name="multiplyService"> <interface.java interface="calculator.dosgi.operations.MultiplyService"/> </reference> <reference name="divideService"> <interface.java interface="calculator.dosgi.operations.DivideService"/> </reference> </componentType>

  21. SCA composite for the OSGi bundle <compositexmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903“ xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.1“ targetNamespace=http://calculator.dosginame="CalculatorComposite"> <componentname="CalculatorComponent"> <tuscany:implementation.osgibundleSymbolicName="calculator.dosgi"bundleVersion="1.0.0"/> <servicename="CalculatorService"> <binding.wsuri="http://localhost:8086/CalculatorService"/> </service> <referencename="addService"> <tuscany:binding.rmiuri="rmi://localhost:8085/AddService"/> </reference> <referencename="subtractService"> <tuscany:binding.rmiuri="rmi://localhost:8085/SubtractService"/> </reference> <referencename="multiplyService"> <tuscany:binding.rmiuri="rmi://localhost:8085/MultiplyService"/> </reference> <referencename="divideService"> <tuscany:binding.rmiuri="rmi://localhost:8085/DivideService"/> </reference> </component> </composite>

  22. On-demand mapping from OSGi to SCAhttp://svn.apache.org/repos/asf/tuscany/java/sca/samples/dosgi-dynamic-calculator/http://svn.apache.org/repos/asf/tuscany/java/sca/samples/dosgi-dynamic-calculator-operations/

  23. Remote Service Admin NOTE: The diagram is copied from OSGi Remote Service Admin spec (to be published)

  24. Remote Services with SCA NOTE: The diagram is copied from OSGi Remote Service SCA Configuration Type spec (to be published)

  25. Publish remote services publicvoid start(BundleContext context) throws Exception { Dictionary<String, Object> props = new Hashtable<String, Object>(); props.put("sca.service", "CalculatorComponent#service-name(Calculator)"); props.put("calculator", "Calculator"); props.put("service.exported.configs", new String[] {"org.osgi.sca"}); props.put("org.osgi.sca.bindings", new String[] {"{http://sample}Calculator"}); props.put("service.exported.interfaces", new String[] {"*"}); CalculatorService calculator = new CalculatorServiceImpl(context); context.registerService(CalculatorService.class.getName(), calculator, props); }

  26. Look up remote services (ServiceTracker) Filter remoteFilter = null; try { remoteFilter = context.createFilter("(&(" + OBJECTCLASS + "=calculator.dosgi.operations.*) (service.imported=*))"); } catch (InvalidSyntaxException e) { … } this.remoteServices = new ServiceTracker(context, remoteFilter, null); remoteServices.open(); … Object[] remoteObjects = remoteServices.getServices();

  27. MANIFEST.MF Manifest-Version: 1.0 Export-Package: calculator.dosgi;version="1.0.1", calculator.dosgi.operations;version="1.0.1" Bundle-Version: 1.0.0 Bundle-Name: calculator.dosgi.dynamic Bundle-Activator: calculator.dosgi.impl.CalculatorActivator Bundle-ManifestVersion: 2 Import-Package: org.oasisopen.sca.annotation;version="2.0.0", org.osgi.framework, org.osgi.service.component;resolution:=optional, org.osgi.service.packageadmin, org.osgi.util.tracker Bundle-SymbolicName: calculator.dosgi.dynamic Bundle-ActivationPolicy: lazy Bundle-RequiredExecutionEnvironment: J2SE-1.5,JavaSE-1.6 SCA-Configuration: OSGI-INF/sca-config/calculator-config.xml Remote-Service: OSGI-INF/remote-service/*.xml

  28. SCA Configuration <scact:sca-config targetNamespace="http://sample" xmlns:scact="http://www.osgi.org/xmlns/scact/v1.0.0" xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903" xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.1"> <sca:binding.ws name="Calculator" uri="http://localhost:8086/CalculatorService"/> <!-- bindings for the remote services --> <tuscany:binding.rmi name="Add" uri="rmi://localhost:8085/AddService"/> <tuscany:binding.rmi name="Divide" uri="rmi://localhost:8085/DivideService"/> <tuscany:binding.rmi name="Subtract" uri="rmi://localhost:8085/SubtractService"/> <tuscany:binding.rmi name="Multiply" uri="rmi://localhost:8085/MultiplyService"/> </scact:sca-config>

  29. Local endpoint descriptions <service-descriptions xmlns="http://www.osgi.org/xmlns/sd/v1.0.0" xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903" xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.1"> <!-- Describe a remote OSGi service --> <service-description> <provide interface="calculator.dosgi.operations.AddService" /> <property name="remote.exported.intents"></property> <property name="remote.configs.supported">org.osgi.sca</property> <property name="org.osgi.sca.bindings">{http://sample}Add</property> </service-description> … </service-descriptions>

  30. SCA Domain based service discovery

  31. Domain Registry for OSGi discovery

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