OSGi Remote Services with SCA using Apache Tuscany. Raymond Feng

Transcription

1 OSGi Remote s 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 local service 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 s 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 s NOTE: The diagram is copied from OSGi Platform Compendium R4.2 spec

7 Related OSGi specs OSGi Platform Release 4 Version 4.2 Compendium Specification Chapter 13: Remote s (PM, concepts and properties) Early Access draft of the OSGi 4.2 Enterprise Release SCA Configuration Type (SCA specific properties) Remote Admin (runtime architecture, SPIs)

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

9 Remote Admin Remote Admin This specification adds an extra layer on top of the existing Remote s spec (chapter 13 in the 4.2 Compendium). The Distribution Provider registers a RemoteAdmin 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 Calculator Subtract Multiply Calculator bundle Divide Operations Bundle OSGi service OSGi service reference Calculator OSGi service interface 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 Calculator and it looks up the Add/Subtract/Multiply/Divide services (which are remote over RMI) from the service registry. The Calculator is exported as a Web. The operations bundle registers four remote services (Add/Subtract/Multiply/Divide). These services are exported over RMI.

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

14 Modeling OSGi entities using SCA

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

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

20 Mapping an OSGi bundle to an SCA componenttype <componenttype xmlns=" xmlns:t=" <!-- The service elment defines an SCA view of the OSGi service --> <service name="calculator"> <!-- The interface will be mapped into the OSGi service class --> <interface.java interface="calculator.dosgi.calculator"/> </service> <!-- The reference elment defines an SCA proxy to a remote OSGi service --> <reference name="add"> <interface.java interface="calculator.dosgi.operations.add"/> </reference> <reference name="subtract"> <interface.java interface="calculator.dosgi.operations.subtract"/> </reference> <reference name="multiply"> <interface.java interface="calculator.dosgi.operations.multiply"/> </reference> <reference name="divide"> <interface.java interface="calculator.dosgi.operations.divide"/> </reference> </componenttype>

21 SCA composite for the OSGi bundle <composite xmlns=" xmlns:tuscany=" targetnamespace= name="calculatorcomposite"> <component name="calculatorcomponent"> <tuscany:implementation.osgi bundlesymbolicname="calculator.dosgi" bundleversion="1.0.0" /> <service name="calculator"> <binding.ws uri=" </service> <reference name="add"> <tuscany:binding.rmi uri="rmi://localhost:8085/add"/> </reference> <reference name="subtract"> <tuscany:binding.rmi uri="rmi://localhost:8085/subtract"/> </reference> <reference name="multiply"> <tuscany:binding.rmi uri="rmi://localhost:8085/multiply"/> </reference> <reference name="divide"> <tuscany:binding.rmi uri="rmi://localhost:8085/divide"/> </reference> </component> </composite>

22 On-demand mapping from OSGi to SCA

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

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

25 Publish remote services public void start(bundlecontext context) throws Exception { Dictionary<String, Object> props = new Hashtable<String, Object>(); props.put("sca.service", "CalculatorComponent#servicename(Calculator)"); props.put("calculator", "Calculator"); props.put("service.exported.configs", new String[] {"org.osgi.sca"}); props.put("org.osgi.sca.bindings", new String[] {"{ props.put("service.exported.interfaces", new String[] {"*"}); Calculator calculator = new CalculatorImpl(context); context.register(calculator.class.getname(), calculator, props); }

26 Look up remote services (Tracker) Filter remotefilter = null; try { remotefilter = context.createfilter("(&(" + OBJECTCLASS + "=calculator.dosgi.operations.*) (service.imported=*))"); } catch (InvalidSyntaxException e) { } this.remotes = new Tracker(context, remotefilter, null); remotes.open(); Object[] remoteobjects = remotes.gets();

27 MANIFEST.MF Manifest-Version: 1.0 Export-Package: calculator.dosgi;version="1.0.1", calculator.dosgi.operations;version="1.0.1" Bundle-Version: 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-: OSGI-INF/remote-service/*.xml

28 SCA Configuration <scact:sca-config targetnamespace=" xmlns:scact=" xmlns:sca=" xmlns:tuscany=" <sca:binding.ws name="calculator" uri=" <!-- bindings for the remote services --> <tuscany:binding.rmi name="add" uri="rmi://localhost:8085/add"/> <tuscany:binding.rmi name="divide" uri="rmi://localhost:8085/divide"/> <tuscany:binding.rmi name="subtract" uri="rmi://localhost:8085/subtract"/> <tuscany:binding.rmi name="multiply" uri="rmi://localhost:8085/multiply"/> </scact:sca-config>

29 Local endpoint descriptions <service-descriptions xmlns=" xmlns:sca=" xmlns:tuscany=" <!-- Describe a remote OSGi service --> <service-description> <provide interface="calculator.dosgi.operations.add" /> <property name="remote.exported.intents"></property> <property name="remote.configs.supported">org.osgi.sca</property> <property name="org.osgi.sca.bindings">{ </service-description> </service-descriptions>

30 SCA Domain based service discovery

31 Local/Domain Registry for OSGi discovery Local Tracker OSGi Registry Calculator Local OSGi Implementation Endpoint descriptions in Local XML file RMI Node OSGi Registry Add Subtract ListenerHook Filter Matching SCA Domain Registry Endpoints Intent/PolicySet Definitions Add Subtract Multiply Multiply Divide RMI Divide SCA proxies Node SCA Domain OSGi runtime #1 OSGi runtime #2