OSGi R7 Features

October 5, 2017 4 minute read

Here’s a brief rundown of new features added in OSGi R7 release (from core and compendium).

New Developers and SCM metadata headers:

Bundle-Developers: raymond.auge;email=raymond.auge@liferay.com;name="Raymond Augé"; organization="Liferay, Inc."
Bundle-SCM: url=https://github.com/liferay/foo,connection=scm:git:https://github.com/liferay/foo.git,developerConnection=scm:git:git@github.com:liferay/foo.git

Manifest Annotations build-time annotations designed to ease metadata maintenance

Manifest Annotations

@Header @Headers
@Capability @Capabilities
@Requirement @Requirements
@Attribute @Directive
@Requirement.Resolution @Requirement.Cardinality
@Export @Export.Substitution

Arbitrary headers

@Headers({
  @Header(name = "X-FooHeader", value = "foo"),
  @Header(name = "X-FumHeader", value = "fum")
})
public @interface MyHeaders {}

User defined manifest header meta-annotations:

@Capability(namespace = "my.namespace")
public @interface MyCapability {
  @Attribute("attr") String value();
}

@MyCapability("foo")
public MyClass {}

101 Log Service

Logging API: Logger, LoggerFactory, LogLevel

@Reference
LoggerFactory loggerFactory;
Logger logger = loggerFactory.getLogger(Bar.class);
logger.error("Seems {} has erred", foo, exception);

Streaming log handler: LogStreamProvider

@Reference
LogStreamProvider logStreamProvider;
logStreamProvider.createStream()
.forEach(l -> System.out.println(l))
.onResolve(() -> System.out.println("stream closed"));

Logging configuration: LoggerAdmin, LoggerContext: declarative and programmatic configuration

@Reference
LoggerAdmin loggerAdmin;
loggerAdmin.getLoggerContext("com.foo.bar").setLogLevels(...);

example configuration for PID org.osgi.service.log.admin|com.foo.bar:
```
com.foo.bar.Impl=DEBUG
```

104 Configuration Admin Service

Named factory instances, read-only, passive update, pre-processed configurations

Configuration c = configurationAdmin.getFactoryConfiguration(
  factoryPid, name, "?");
c.addAttributes(ConfigurationAttribute.READ_ONLY);
c.updateIfDifferent(properties);
Dictionary<String,Object> d = c.getProcessedProperties(
  ServiceReference<?> reference);

112 Declarative Services

Activation/constructor injection

@Activate
public Foo(@Reference Bar bar) {...}
@Activate
void activate(Config config, @Reference Bar bar) {...}

Logger support
```
@Reference
Logger logger;
```

Factory properties

@Component(
  factoryProperties="OSGI-INF/factory.properties",
  factoryProperty="hours:Integer=24"
)

Detect change to runtime via service.changecount runtime service property

@Reference(name = "src", updated = "set")
void set(ServiceComponentRuntime scr){...}

Component property types

@ComponentPropertyType
public @interface Config {
boolean enabled() default true;
String[] names() default {"a", "b"};
}
@Component
@Config(names="myapp")
@ServiceRanking(100)
public class MyComponent {
  @Activate void activate(Config config) {...}
}

Added support for JPA 2.1

Standard configuration properties
Updated configuration lifecycle rules

New EntityManagerFactoryBuilder methods

String n = entityManagerFactoryBuilder
  .getPersistenceProviderName();
Bundle b = entityManagerFactoryBuilder
  .getPersistenceProviderBundle();

136 Resolver Service

Define resolution of fragments

Collection<Resource> rs = resolveContext.findRelatedResources(resource);

Define substitution wires

List<Wire> ws = resolveContext.getSubstitutionWires(wiring);

Cancelable resolution callback

resolveContext.onCancel(() -> {/* do something */});

Define dynamic resolving

resolver.resolveDynamic(resolveContext, wiring, requirement);

140 Http Whiteboard

Standard Component property types

@Component(
  scope = ServiceScope.PROTOTYPE, service = Servlet.class)
@HttpWhiteboardServletPattern("/as")
class MyServlet extends HttpServlet {}

Multipart support

@Component(
  scope = ServiceScope.PROTOTYPE, service = Servlet.class)
@HttpWhiteboardServletPattern("/as")
@HttpWhiteboardServletMultipart(maxFileSize = 10000)
class MyServlet extends HttpServlet {}

Servlet pre-processors, execute before security, filter chain finishSecurity method

@Component
@HttpWhiteboardTarget("(foo=bar)")
class myPP implements Preprocessor {...}
if (handleSecurity(req, res)) {
  try {/* do filter chain/servlet */
  } finally {
      finishSecurity(req, res);
  }
}

Detect changes via service.changecount runtime service property

@Reference(updated = "setHttpServiceRuntime", policy = DYNAMIC, policyOption = GREEDY)
void setHttpServiceRuntime(HttpServiceRuntime hsr){
  // has changed
}

HttpService integration

@Component(
  scope=ServiceScope.PROTOTYPE, service = Filter.class)
@HttpWhiteboardFilterPattern("/*")
@HttpWhiteboardContextSelect(
  "(osgi.http.whiteboard.context.httpservice=*)")
public class MyFilter implements Filter {...}

147 Transaction Control Service NEW

Portable, modular abstraction for Transaction lifecycle management

final TransactionControl tc;
final Connection connection;
@Activate public Messenger(
  @Reference TransactionControl tc,
  @Reference JDBCConnectionProvider provider) {
  this.tc = tc;
  this.connection = provider.getResrouce(control)
}
public void addMessage(String message) {
  tc.required(() -> { //start scope
      PreparedStatement ps = connection.prepareStatement(
          "Insert into MESSAGE values ( ? )");
      ps.setString(1, message);
      return ps.executeUpdate();
  }); // end scope
}

Allow different resource types to be easily used within a Transaction
Exception handling
Rollback avoidance
Multithreading
Associate resources with scope
TX lifecycle callbacks
Enlist resources with TX
Mark TX for rollback
Local & XA
Builder pattern
Resource providers
etc.

148 Cluster Information NEW

API for a management agent to discover, list and inspect available nodes in the cluster.

Property Prefix: osgi.clusterinfo.
NodeStatus service properties:
```
Map<String, Object> m = nodeStatus.getMetrics(names);
```
- id
- cluster
- parent
- endpoint
- endpoint.private
- vendor
- version
- country
- location
- region
- zone
- tags
FrameworkNodeStatus properties:
```
interface FrameworkNodeStatus
  extends FrameworkManager, NodeStatus {}

BundleDTO bdto = frameworkNodeStatus.installBundle(location);
```
- org.osgi.framework.version
- org.osgi.framework.processor
- org.osgi.framework.os_name
- java.version
- java.runtime.version
- java.specification.version
- java.vm.version

150 Configurator NEW

Feed configurations into Configuration Admin through

configuration resources, multiple PIDs, multiple
configuration resources, extender pattern, UTF-8 encoded

JSON resources, installed via bundles e.g. OSGI-INF/configurator/foo.json:

{
  // Global Settings
  ":configurator:resource-version" : 1,
  "pid.a": {
      "key": "val",
      "some_number": 123
  },
  "factory.pid.b~name": {
      "a_boolean": true
  }
}

Ranking, factory configs, typed, binary data, overwrite

{
  "my.config": {
      "security.enabled": true,
      "public.key:binary" : "/OSGI-INF/files/mykey.pub"
  }
}

policy, well defined lifecycle, via system property, coordinator -Dconfigurator.initial={"pid.a": {"some_number": 123}} -Dconfigurator.initial=file:/some.json,file:/other.json
integration, standalone configurations

151 JAX-RS Whiteboard NEW

Extensions as services, simple collaboration model

@Component(service = Foo.class)
@JaxrsName("foo") @JaxrsResource @Path("foo")
class Foo {
  @GET @Path("{name}")
  public String interrogateSession(
      @PathParam("name") String name,
      @Context HttpServletRequest req) {

     HttpSession s = req.getSession();
     return String.valueOf(s.getAttribute(name));
  }
}

Require extensions, static resources, multiple whiteboards with own endpoints, simplified default applications,
```
@Component
@JaxrsExtensionSelect("(osgi.jaxrs.name=configProvider)")
```

Detect runtime changes via service.changecount runtime service property:

@Reference(updated = "setJaxRSServiceRuntime", policy = DYNAMIC, policyOption = GREEDY)
void setJaxRSServiceRuntime(JaxRSServiceRuntime runtime){
  // has changed
}

705 Promises

Thrown exceptions in Function and Predicate, timeout/delay, specify executor/scheduledExecutor, support Callback from org.osgi.util.function

final Promise<String> answer = new Deferred<String>(
  executor, scheduledExecutor
).getPromise().delay(1000).timeout(5000).then(
  new Callback() {
      @Override
      public void run() throws Exception {
          System.out.println(answer);
      }
  }
);

706 Push Stream NEW

Compact pipeline asynchronous tasks on event arrival, circuit breaker, finite streams & back pressure explicit in API signatures, inspired by Java 8 Streams API, independent, generics, lazy, composed by functional steps, mapping, flat mapping, filtering, stateless & stateful intermediate operations
```
PushEventSource<Integer> source = ...
Integer i = new PushStreamProvider().buildStream(source)
  .withPushbackPolicy(LINEAR, 20)
  .withQueuePolicy(FAIL)
  .build()
  .max(Integer::compare)
  .getValue().get();
```

707 Converter NEW

Make it easy to convert many types to other types, scalars, collections, maps, beans, interfaces and DTOs, no boilerplate conversion code, customized using converter builders, generics, rules

Converter c = Converters.standardConverter();
MyEnum e = c.convert(MyOtherEnum.BLUE).to(MyEnum.class);
BigDecimal bd = c.convert(12345).to(BigDecimal.class);
long[] la = c.convert(
  Arrays.asList("978", "142")).to(long[].class);
Map m = Collections.singletonMap("timeout", "700");
int t = c.convert(m).to(MyInterface.class).timeout();
Map m = Collections.singletonMap("args", null)
String[] a1 = c.convert(m).to(MyAnnotation.class).args();

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