Convert DittoExtensionPoint to an interface

* Extension points are not meant to contain logic which should be reused,
  they should define a code interface which should be available at the place
  where the extension is used
* Also made all implementations final

Signed-off-by: Yannic Klem <Yannic.Klem@bosch.io>

base/service/src/main/java/org/eclipse/ditto/base/service/DittoExtensionPoint.java

@@ -27,21 +27,12 @@
  *
  * @since 3.0.0
  */
-public abstract class DittoExtensionPoint implements Extension {
-
-    protected final ActorSystem actorSystem;
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected DittoExtensionPoint(final ActorSystem actorSystem) {
-        this.actorSystem = actorSystem;
-    }
+public interface DittoExtensionPoint extends Extension {
 
     /**
      * @param <T> the class of the extension for which an implementation should be loaded.
      */
-    protected static final class ExtensionId<T extends Extension> extends AbstractExtensionId<T> {
+    final class ExtensionId<T extends Extension> extends AbstractExtensionId<T> {
 
         private final String implementation;
         private final Class<T> parentClass;

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/directives/auth/DittoGatewayAuthenticationDirectiveFactory.java

@@ -24,7 +24,9 @@
 import org.eclipse.ditto.gateway.service.security.authentication.jwt.JwtAuthenticationFactory;
 import org.eclipse.ditto.gateway.service.security.authentication.jwt.JwtAuthenticationProvider;
 import org.eclipse.ditto.gateway.service.security.authentication.preauth.PreAuthenticatedAuthenticationProvider;
+import org.eclipse.ditto.gateway.service.util.config.DittoGatewayConfig;
 import org.eclipse.ditto.gateway.service.util.config.security.AuthenticationConfig;
+import org.eclipse.ditto.internal.utils.config.DefaultScopedConfig;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -35,7 +37,7 @@
 /**
  * Ditto's default factory for building authentication directives.
  */
-public final class DittoGatewayAuthenticationDirectiveFactory extends GatewayAuthenticationDirectiveFactory {
+public final class DittoGatewayAuthenticationDirectiveFactory implements GatewayAuthenticationDirectiveFactory {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(DittoGatewayAuthenticationDirectiveFactory.class);
     private static final String AUTHENTICATION_DISPATCHER_NAME = "authentication-dispatcher";
@@ -46,8 +48,8 @@ public final class DittoGatewayAuthenticationDirectiveFactory extends GatewayAut
     @Nullable private GatewayAuthenticationDirective gatewayWsAuthenticationDirective;
 
     public DittoGatewayAuthenticationDirectiveFactory(final ActorSystem actorSystem) {
-        super(actorSystem);
-        authConfig = getAuthConfig(actorSystem);
+        authConfig = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(actorSystem.settings().config()))
+                .getAuthenticationConfig();
         authenticationDispatcher = actorSystem.dispatchers().lookup(AUTHENTICATION_DISPATCHER_NAME);
     }
 

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/directives/auth/GatewayAuthenticationDirectiveFactory.java

@@ -25,32 +25,21 @@
 /**
  * Factory for authentication directives.
  */
-public abstract class GatewayAuthenticationDirectiveFactory extends DittoExtensionPoint {
-
-    protected static final String AUTHENTICATION_DISPATCHER_NAME = "authentication-dispatcher";
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected GatewayAuthenticationDirectiveFactory(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
+public interface GatewayAuthenticationDirectiveFactory extends DittoExtensionPoint {
 
     /**
      * Builds the {@link GatewayAuthenticationDirective authentication directive} that should be used for HTTP API.
      *
      * @return The built {@link GatewayAuthenticationDirective authentication directive}.
      */
-    public abstract GatewayAuthenticationDirective buildHttpAuthentication(
-            JwtAuthenticationFactory jwtAuthenticationFactory);
+    GatewayAuthenticationDirective buildHttpAuthentication(JwtAuthenticationFactory jwtAuthenticationFactory);
 
     /**
      * Builds the {@link GatewayAuthenticationDirective authentication directive} that should be used for WebSocket API.
      *
      * @return The built {@link GatewayAuthenticationDirective authentication directive}.
      */
-    public abstract GatewayAuthenticationDirective buildWsAuthentication(
-            JwtAuthenticationFactory jwtAuthenticationFactory);
+    GatewayAuthenticationDirective buildWsAuthentication(JwtAuthenticationFactory jwtAuthenticationFactory);
 
     /**
      * Loads the implementation of {@code GatewayAuthenticationDirectiveFactory} which is configured for the
@@ -61,15 +50,13 @@ public abstract GatewayAuthenticationDirective buildWsAuthentication(
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      * @since 3.0.0
      */
-    public static GatewayAuthenticationDirectiveFactory get(final ActorSystem actorSystem) {
+    static GatewayAuthenticationDirectiveFactory get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
-        final var implementation = getAuthConfig(actorSystem).getGatewayAuthenticationDirectiveFactory();
-
+        final AuthenticationConfig authenticationConfig =
+                DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(actorSystem.settings().config()))
+                        .getAuthenticationConfig();
+        final var implementation = authenticationConfig.getGatewayAuthenticationDirectiveFactory();
         return new ExtensionId<>(implementation, GatewayAuthenticationDirectiveFactory.class).get(actorSystem);
     }
 
-    protected static AuthenticationConfig getAuthConfig(final ActorSystem actorSystem) {
-        return DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
-                actorSystem.settings().config())).getAuthenticationConfig();
-    }
 }

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/CustomApiRoutesProvider.java

@@ -27,11 +27,7 @@
  * Provider for custom routes.
  * You can distinguish between routes for unauthorized access and authorized access.
  */
-public abstract class CustomApiRoutesProvider extends DittoExtensionPoint {
-
-    protected CustomApiRoutesProvider(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
+public interface CustomApiRoutesProvider extends DittoExtensionPoint {
 
     /**
      * Provides a custom route for unauthorized access.
@@ -41,8 +37,7 @@ protected CustomApiRoutesProvider(final ActorSystem actorSystem) {
      * @param correlationId the correlation ID.
      * @return custom route for unauthorized access.
      */
-    public abstract Route unauthorized(RouteBaseProperties routeBaseProperties, JsonSchemaVersion version,
-            CharSequence correlationId);
+    Route unauthorized(RouteBaseProperties routeBaseProperties, JsonSchemaVersion version, CharSequence correlationId);
 
     /**
      * Provides a custom route for authorized access.
@@ -51,7 +46,7 @@ public abstract Route unauthorized(RouteBaseProperties routeBaseProperties, Json
      * @param headers headers of the request.
      * @return custom route for authorized access.
      */
-    public abstract Route authorized(RouteBaseProperties routeBaseProperties, DittoHeaders headers);
+    Route authorized(RouteBaseProperties routeBaseProperties, DittoHeaders headers);
 
     /**
      * Loads the implementation of {@code CustomApiRoutesProvider} which is configured for the {@code ActorSystem}.
@@ -61,7 +56,7 @@ public abstract Route unauthorized(RouteBaseProperties routeBaseProperties, Json
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      * @since 3.0.0
      */
-    public static CustomApiRoutesProvider get(final ActorSystem actorSystem) {
+    static CustomApiRoutesProvider get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
         final var implementation = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
                 actorSystem.settings().config())).getHttpConfig().getCustomApiRoutesProvider();

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/HttpBindFlowProvider.java

@@ -29,21 +29,14 @@
  * Extension to add a custom bind flow for HTTP requests.
  * @since 3.0.0
  */
-public abstract class HttpBindFlowProvider extends DittoExtensionPoint {
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected HttpBindFlowProvider(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
+public interface HttpBindFlowProvider extends DittoExtensionPoint {
 
     /**
      * Create a bind flow for HTTP requests.
      *
      * @return flow which processes HTTP requests.
      */
-    public abstract Flow<HttpRequest, HttpResponse, NotUsed> getFlow(final Route innerRoute);
+    Flow<HttpRequest, HttpResponse, NotUsed> getFlow(final Route innerRoute);
 
     /**
      * Loads the implementation of {@code HttpBindFlowProvider} which is configured for the
@@ -53,7 +46,7 @@ protected HttpBindFlowProvider(final ActorSystem actorSystem) {
      * @return the {@code HttpBindFlowProvider} implementation.
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      */
-    public static HttpBindFlowProvider get(final ActorSystem actorSystem) {
+    static HttpBindFlowProvider get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
         final var implementation = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
                 actorSystem.settings().config())).getHttpConfig().getBindFlowProvider();

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/LoggingHttpBindFlowProvider.java

@@ -23,15 +23,18 @@
 
 /**
  * Default HTTP bind flow provider, which logs the requests.
+ *
  * @since 3.0.0
  */
-public class LoggingHttpBindFlowProvider extends HttpBindFlowProvider {
+public final class LoggingHttpBindFlowProvider implements HttpBindFlowProvider {
+
+    private final ActorSystem actorSystem;
 
     /**
      * @param actorSystem the actor system in which to load the extension.
      */
-    protected LoggingHttpBindFlowProvider(final ActorSystem actorSystem) {
-        super(actorSystem);
+    public LoggingHttpBindFlowProvider(final ActorSystem actorSystem) {
+        this.actorSystem = actorSystem;
     }
 
     @Override

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/NoopCustomApiRoutesProvider.java

@@ -22,12 +22,12 @@
 import akka.http.javadsl.server.Route;
 
 @Immutable
-public final class NoopCustomApiRoutesProvider extends CustomApiRoutesProvider {
+public final class NoopCustomApiRoutesProvider implements CustomApiRoutesProvider {
 
     private static final Route EMPTY_ROUTE = Directives.reject();
 
     public NoopCustomApiRoutesProvider(final ActorSystem actorSystem) {
-        super(actorSystem);
+        // No-Op because Extensions need to have constructor accepting the actorSystem.
     }
 
     @Override

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/NoOpSseAuthorizationEnforcer.java

@@ -23,13 +23,13 @@
 /**
  * Null implementation for {@link SseAuthorizationEnforcer}.
  */
-public final class NoOpSseAuthorizationEnforcer extends SseAuthorizationEnforcer {
+public final class NoOpSseAuthorizationEnforcer implements SseAuthorizationEnforcer {
 
     /**
      * @param actorSystem the actor system in which to load the extension.
      */
     public NoOpSseAuthorizationEnforcer(final ActorSystem actorSystem) {
-        super(actorSystem);
+        //No-Op because extensions need a constructor accepting an actorSystem
     }
 
     @Override

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/NoOpSseConnectionSupervisor.java

@@ -20,13 +20,13 @@
 /**
  * Null implementation for {@link SseConnectionSupervisor}.
  */
-public final class NoOpSseConnectionSupervisor extends SseConnectionSupervisor {
+public final class NoOpSseConnectionSupervisor implements SseConnectionSupervisor {
 
     /**
      * @param actorSystem the actor system in which to load the extension.
      */
     public NoOpSseConnectionSupervisor(final ActorSystem actorSystem) {
-        super(actorSystem);
+        //No-Op because extensions need a constructor accepting an actorSystem
     }
 
     @Override

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/NoOpSseEventSniffer.java

@@ -17,24 +17,19 @@
 import akka.http.javadsl.model.HttpRequest;
 import akka.http.javadsl.model.sse.ServerSentEvent;
 import akka.stream.javadsl.Flow;
-import akka.stream.javadsl.Sink;
 
 /**
  * Sniffer for Server Sent Events that does purposefully nothing.
  */
-public class NoOpSseEventSniffer extends SseEventSniffer {
+public final class NoOpSseEventSniffer implements SseEventSniffer {
 
     public NoOpSseEventSniffer(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
-
-    @Override
-    public Sink<ServerSentEvent, ?> createSink(final HttpRequest request) {
-        return Sink.ignore();
+        //No-Op because extensions need a constructor accepting an actorSystem
     }
 
     @Override
     public Flow<ServerSentEvent, ServerSentEvent, NotUsed> toAsyncFlow(final HttpRequest request) {
         return Flow.create();
     }
+
 }

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/SseAuthorizationEnforcer.java

@@ -29,14 +29,7 @@
  * If the authorization check is successful nothing will happen, else a
  * {@link org.eclipse.ditto.base.model.exceptions.DittoRuntimeException DittoRuntimeException} is thrown.
  */
-public abstract class SseAuthorizationEnforcer extends DittoExtensionPoint {
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected SseAuthorizationEnforcer(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
+public interface SseAuthorizationEnforcer extends DittoExtensionPoint {
 
     /**
      * Ensures that the establishment of a SSE connection is authorized for the given arguments.
@@ -46,8 +39,7 @@ protected SseAuthorizationEnforcer(final ActorSystem actorSystem) {
      * @return a successful future if validation succeeds or a failed future if validation fails.
      * @throws NullPointerException if any argument is {@code null}.
      */
-    protected abstract CompletionStage<Void> checkAuthorization(RequestContext requestContext,
-            DittoHeaders dittoHeaders);
+    CompletionStage<Void> checkAuthorization(RequestContext requestContext, DittoHeaders dittoHeaders);
 
     /**
      * Loads the implementation of {@code SseAuthorizationEnforcer} which is configured for the
@@ -58,7 +50,7 @@ protected abstract CompletionStage<Void> checkAuthorization(RequestContext reque
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      * @since 3.0.0
      */
-    public static SseAuthorizationEnforcer get(final ActorSystem actorSystem) {
+    static SseAuthorizationEnforcer get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
         final var implementation = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
                 actorSystem.settings().config())).getStreamingConfig().getSseConfig().getAuthorizationEnforcer();

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/SseConnectionSupervisor.java

@@ -24,14 +24,7 @@
 /**
  * Provides the means to supervise a particular SSE connection.
  */
-public abstract class SseConnectionSupervisor extends DittoExtensionPoint implements StreamSupervisor{
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected SseConnectionSupervisor(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
+public interface SseConnectionSupervisor extends DittoExtensionPoint, StreamSupervisor{
 
     /**
      * Loads the implementation of {@code SseConnectionSupervisor} which is configured for the
@@ -42,7 +35,7 @@ protected SseConnectionSupervisor(final ActorSystem actorSystem) {
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      * @since 3.0.0
      */
-    public static SseConnectionSupervisor get(final ActorSystem actorSystem) {
+    static SseConnectionSupervisor get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
         final var implementation = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
                 actorSystem.settings().config())).getStreamingConfig().getSseConfig().getConnectionSupervisor();

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/endpoints/routes/sse/SseEventSniffer.java

@@ -30,36 +30,15 @@
 /**
  * Functional interface to sniff events over or SSE.
  */
-public abstract class SseEventSniffer extends DittoExtensionPoint {
-
-    /**
-     * @param actorSystem the actor system in which to load the extension.
-     */
-    protected SseEventSniffer(final ActorSystem actorSystem) {
-        super(actorSystem);
-    }
-
-    /**
-     * Create a receiver for sniffed events.
-     *
-     * @param request the HTTP request that started the event stream.
-     * @return sink to send events into.
-     */
-    protected abstract Sink<ServerSentEvent, ?> createSink(HttpRequest request);
+public interface SseEventSniffer extends DittoExtensionPoint {
 
     /**
      * Create an async flow for event sniffing.
      *
      * @param request the HTTP request that started the event stream.
      * @return flow to pass events through with a wiretap attached over an async barrier to the sink for sniffed events.
      */
-    protected Flow<ServerSentEvent, ServerSentEvent, NotUsed> toAsyncFlow(final HttpRequest request) {
-        return Flow.<ServerSentEvent>create().wireTap(
-                Flow.<ServerSentEvent>create()
-                        .async()
-                        .to(Sink.lazyCompletionStageSink(() -> CompletableFuture.completedFuture(
-                                createSink(request)))));
-    }
+    Flow<ServerSentEvent, ServerSentEvent, NotUsed> toAsyncFlow(final HttpRequest request);
 
     /**
      * Loads the implementation of {@code SseEventSniffer} which is configured for the
@@ -70,7 +49,7 @@ protected Flow<ServerSentEvent, ServerSentEvent, NotUsed> toAsyncFlow(final Http
      * @throws NullPointerException if {@code actorSystem} is {@code null}.
      * @since 3.0.0
      */
-    public static SseEventSniffer get(final ActorSystem actorSystem) {
+    static SseEventSniffer get(final ActorSystem actorSystem) {
         checkNotNull(actorSystem, "actorSystem");
         final var implementation = DittoGatewayConfig.of(DefaultScopedConfig.dittoScoped(
                 actorSystem.settings().config())).getStreamingConfig().getSseConfig().getEventSniffer();