How to connect your OSGi application - Dirk Fauth (Bosch)

HOW TO CONNECT
YOUR
OSGI APPLICATION

Automotive Service Solutions | AA-AS/EIS2-EU | 23.10.2018
© Robert Bosch GmbH 2018. Alle Rechte vorbehalten, auch bzgl. jeder Verfügung, Verwertung, Reproduktion, Bearbeitung, Weitergabe sowie für den Fall von Schutzrechtsanmeldungen.
2
How to connect your OSGi application
Speaker
Dirk Fauth
System-Architect
Eclipse Committer
Robert Bosch GmbH
Franz-Oechsle-Straße 4
73207 Plochingen
dirk.fauth@de.bosch.com
www.bosch.com
blog.vogella.com/author/fipro/
Twitter: fipro78

4
Introduction
Application A Application B
S
S
S
S
Communication Protocol,
e.g. JSON via HTTP
What does OSGi provide to realize this szenario?

5
Setup
JVM
OSGi Framework
JSON Converter
Servlet Container
???
e.g. Equinox or Felix
SCR Felix SCR
e.g. Jetty
Application / Services
e.g. Jackson

6
Setup - Service
public interface StringModifier {
String modify(String input);
}
@Component
public class StringInverter implements StringModifier {
@Override
public String modify(String input) {
return new StringBuilder(input).reverse().toString();
}
}
M(ost) U(seless) S(ervice) E(ver)

8
HTTP Service / HTTP Whiteboard
JVM
OSGi Framework
JSON Converter
Servlet Container
SCR
Servlet

9
@Component(
service=Servlet.class,
property= "osgi.http.whiteboard.servlet.pattern=/modify",
scope=ServiceScope.PROTOTYPE)
public class ModifierServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Reference private volatile List<StringModifier> modifier;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType(MediaType.APPLICATION_JSON);
ObjectMapper objectMapper = new ObjectMapper();
try {
String json = objectMapper.writeValueAsString(
modifier.stream().map(x -> x.modify(input)).collect(toList()));
resp.getWriter().write(json);
} catch (JsonProcessingException e) { ... }
}
}
@Component(
@Override
try {
}
}
@Component(
@Override
try {
}
}

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Service URL: http://localhost:8080/modify?value=Eclipse

11
 Cons
 Dependency to Servlet API
 Conversion done in the service
 Pros
 Very simple
 Small number of bundles

13
Remote Services
Service
Producer
Remote Service
Implementation
endpoint
created by RSA
announced by Discovery
Service
Consumer
endpoint
discovered by Discovery
proxied by RSA
Remote Service
Implementation

15
Remote Services
JVM
OSGi Framework
JSON Converter
Servlet Container
SCR
Remote Service / RSA

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Remote Services
@Component(property= {
"service.exported.interfaces=*",
"service.exported.configs=ecf.generic.server"
})
public class StringInverter implements StringModifier {
@Override
public String modify(String input) {
return new StringBuilder(input).reverse().toString();
}
}

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Remote Services
@Path("/modify")
@Component(
immediate = true,
property = { "service.exported.interfaces=*",
"service.intents=osgi.async",
"service.intents=jaxrs",
"osgi.basic.timeout=50000" })
public class ModifierServiceImpl implements ModifierService {
@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/{value}")
@Override
public List<String> getModifications(@PathParam("value") String value) {
return modifier.stream().map(x -> x.modify(value)).collect(Collectors.toList());
}
}
@Path("/modify")
@Component(
immediate = true,
@GET
@Path("/{value}")
@Override
}
}
@Path("/modify")
@Component(
immediate = true,
@GET
@Path("/{value}")
@Override
}
}

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 Various protocols available (e.g. via ECF)
 Discovery
‒ Zeroconf/aka Bonjour/Rendevous (JmDNS)
‒ jSLP aka SLP/RFC2608
 Distribution Provider
‒ Generic Provider
‒ r-OSGi Provider
‒ Jax-RS Distribution Provider
Remote Services

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Remote Services
Service URL: http://localhost:8080/1/modify/Eclipse

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 Cons
 Complicated bundle composition
 High risk with networking issues
 Client side is an OSGi application
 URL contains dynamic containerID
 Pros
 Simple definition via component
properties
 Usage of default JAX-RS
annotations
 Importing remote services without
efforts in programming
Remote Services

21
JAX-RS Whiteboard
JVM
OSGi Framework
JSON Converter
Servlet Container
SCR
JAX-RS Whiteboard

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JAX-RS Whiteboard
@Path("/modify")
@Component(service=ModifierServiceImpl.class)
@JaxrsResource
@JSONRequired
public class ModifierServiceImpl {
@Reference
private volatile List<StringModifier> modifier;
@GET
@Path("/{value}")
return modifier.stream().map(x -> x.modify(value)).collect(toList());
}
}
@Path("/modify")
@Component(service=ModifierServiceImpl.class)
@JaxrsResource
@JSONRequired
public class ModifierServiceImpl {
@Reference
private volatile List<StringModifier> modifier;
@GET
@Path("/{value}")
return modifier.stream().map(x -> x.modify(value)).collect(toList());
}
}

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JAX-RS Whiteboard
@Component(scope = PROTOTYPE)
@JaxrsExtension
@JaxrsMediaType(APPLICATION_JSON)
public class JacksonJsonConverter<T>
implements MessageBodyReader<T>, MessageBodyWriter<T> {
@Reference(service=LoggerFactory.class)
private Logger logger;
private final Converter converter = Converters.newConverterBuilder()
.rule(String.class, this::toJson)
.rule(this::toObject)
.build();
private ObjectMapper mapper = new ObjectMapper();
...
@Component(scope = PROTOTYPE)
@JaxrsExtension
@JaxrsMediaType(APPLICATION_JSON)
public class JacksonJsonConverter<T>
implements MessageBodyReader<T>, MessageBodyWriter<T> {
@Reference(service=LoggerFactory.class)
private Logger logger;
private final Converter converter = Converters.newConverterBuilder()
.rule(String.class, this::toJson)
.rule(this::toObject)
.build();
private ObjectMapper mapper = new ObjectMapper();
...

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JAX-RS Whiteboard
Service URL: http://localhost:8080/modify/Eclipse

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 Cons
 Only CXF based reference
implementation from Aries
available
 osgi.contract capabilities not
widely integrated yet
 Pros
 Simple definition via Component
Property Types
 Usage of default JAX-RS
annotations
 Easy combination of different
OSGi R7 specifications
 Runtime requirements resolved
via osgi.contract capabilities
JAX-RS Whiteboard

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 OSGi JAX-RS Connector
https://github.com/hstaudacher/osgi-jax-rs-connector
 Inactive for > 3 years
 With R7 actually no use anymore
 enRoute
https://enroute.osgi.org
 Basic guidance for using R7 specifications
 Maven based toolchain
 Custom communication implementations
Alternatives

30
 OSGi Core Release 7 Specification
https://osgi.org/specification/osgi.core/7.0.0/
 OSGi Compendium Release 7 Specification
https://osgi.org/specification/osgi.cmpn/7.0.0/
 Eclipse Communication Framework Wiki
https://wiki.eclipse.org/Eclipse_Communication_Framework_Project#OS
Gi_Remote_Services
References

31
 HTTP Service Specification
https://osgi.org/specification/osgi.cmpn/7.0.0/service.http.html
 HTTP Whiteboard Specification
https://osgi.org/specification/osgi.cmpn/7.0.0/service.http.whiteboard.html
 Remote Services
https://osgi.org/specification/osgi.cmpn/7.0.0/service.remoteservices.html
 Remote Service Admin Service Specification
https://osgi.org/specification/osgi.cmpn/7.0.0/service.remoteserviceadmin
.html
 JAX-RS Whiteboard Specification
https://osgi.org/specification/osgi.cmpn/7.0.0/service.jaxrs.html
References

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 ECF JAX-RS Distribution Provider
https://github.com/ECF/JaxRSProviders
https://wiki.eclipse.org/Tutorial:_Exposing_a_Jax_REST_service_as_an_
OSGi_Remote_Service
 Access OSGi services via web interface
http://blog.vogella.com/2017/04/20/access-osgi-services-via-web-
interface/
 Microservices with OSGi
https://www.eclipsecon.org/europe2017/session/microservices-osgi
https://www.youtube.com/watch?v=IOusIWAziFE
 Example sources
https://github.com/fipro78/access_osgi_services
References

How to connect your OSGi application - Dirk Fauth (Bosch)

How to connect your OSGi application - Dirk Fauth (Bosch)

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