Feature horizontal scalability (#305)

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

examples/hawkbit-example-app/README.md

@@ -33,3 +33,45 @@ The Management API can be accessed via http://localhost:8080/rest/v1
  - **manifest-simple.yml** for a standalone hawkBit installation with embedded H2.
  - **manifest.yml**  for a standalone hawkBit installation with embedded H2 and RabbitMQ service binding for DMF integration (note: this manifest is used for the sandbox above).
 - Run ```cf push``` against you cloud foundry environment.
+
+# Enable Clustering (experimental)
+
+Clustering in hawkBit is based on _Spring Cloud Bus_. It is not enabled in the example app by default.
+
+Add to your `application.properties` :
+
+```
+spring.cloud.bus.enabled=true
+```
+
+Add to your `pom.xml` :
+
+```
+<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
+</dependency>
+```
+
+Optional as well is the addition of [Protostuff](https://github.com/protostuff/protostuff) based message payload serialization for improved performance.
+
+
+Add to your `application.properties` :
+
+```
+spring.cloud.stream.bindings.springCloudBusInput.content-type=application/binary+protostuff
+spring.cloud.stream.bindings.springCloudBusOutput.content-type=application/binary+protostuff
+```
+
+Add to your `pom.xml` :
+
+```
+<dependency>
+	<groupId>io.protostuff</groupId>
+	<artifactId>protostuff-core</artifactId>
+</dependency>
+<dependency>
+	<groupId>io.protostuff</groupId>
+	<artifactId>protostuff-runtime</artifactId>
+</dependency>
+```

examples/hawkbit-example-app/pom.xml

@@ -97,7 +97,6 @@
          <artifactId>hawkbit-repository-jpa</artifactId>
          <version>${project.version}</version>
       </dependency>
-
       <!-- Spring -->
       <dependency>
          <groupId>org.springframework.boot</groupId>

examples/hawkbit-example-app/src/main/java/org/eclipse/hawkbit/app/MyUI.java

@@ -8,14 +8,10 @@
  */
 package org.eclipse.hawkbit.app;
 
-import java.util.concurrent.ScheduledExecutorService;
-
 import org.eclipse.hawkbit.ui.HawkbitUI;
-import org.eclipse.hawkbit.ui.push.DelayedEventBusPushStrategy;
-import org.eclipse.hawkbit.ui.push.UIEventProvider;
-import org.springframework.beans.factory.annotation.Autowired;
+import org.eclipse.hawkbit.ui.push.EventPushStrategy;
+import org.vaadin.spring.events.EventBus.SessionEventBus;
 
-import com.google.common.eventbus.EventBus;
 import com.vaadin.annotations.Push;
 import com.vaadin.shared.communication.PushMode;
 import com.vaadin.shared.ui.ui.Transport;
@@ -35,12 +31,18 @@ import com.vaadin.spring.annotation.SpringUI;
 // Vaadin.
 @SuppressWarnings({ "squid:MaximumInheritanceDepth" })
 public class MyUI extends HawkbitUI {
-
     private static final long serialVersionUID = 1L;
 
-    @Autowired
-    public MyUI(final ScheduledExecutorService scheduledExecutorService, final EventBus systemEventBus,
-            final org.vaadin.spring.events.EventBus.SessionEventBus eventBus, final UIEventProvider provider) {
-        super(new DelayedEventBusPushStrategy(scheduledExecutorService, eventBus, systemEventBus, provider));
+    /**
+     * Constructor
+     * 
+     * @param pushStrategy
+     *            the push strategy
+     * @param eventBus
+     *            the event bus
+     */
+    public MyUI(final EventPushStrategy pushStrategy, final SessionEventBus eventBus) {
+        super(pushStrategy, eventBus);
     }
+
 }