Good evening, According to Flink's documentation I have excluded the Flink runtime library from the runtime dependencies of my project:
dependencies { compileOnly group: 'org.apache.flink', name: 'flink-core', version: '1.4.2' compileOnly group: 'org.apache.flink', name: 'flink-java', version: '1.4.2' compileOnly group: 'org.apache.flink', name: 'flink-streaming-java_2.11', version: '1.4.2' implementation group: 'org.apache.flink', name: 'flink-connector-kafka-0.11_2.11', version: '1.4.2' ... } Unfortunately I get the following error: Caused by: java.lang.ClassCastException: interface akka.serialization.Serializer is not assignable from class akka.remote.serialization.MiscMessageSerializer at akka.actor.ReflectiveDynamicAccess$$anonfun$getClassFor$1.apply(ReflectiveDynamicAccess.scala:23) at akka.actor.ReflectiveDynamicAccess$$anonfun$getClassFor$1.apply(ReflectiveDynamicAccess.scala:20) at scala.util.Try$.apply(Try.scala:192) at akka.actor.ReflectiveDynamicAccess.getClassFor(ReflectiveDynamicAccess.scala:20) at akka.actor.ReflectiveDynamicAccess.createInstanceFor(ReflectiveDynamicAccess.scala:38) at akka.serialization.Serialization.serializerOf(Serialization.scala:301) at akka.serialization.Serialization$$anonfun$6.apply(Serialization.scala:327) at akka.serialization.Serialization$$anonfun$6.apply(Serialization.scala:327) at scala.collection.TraversableLike$WithFilter$$anonfun$map$2.apply(TraversableLike.scala:683) at scala.collection.immutable.HashMap$HashMap1.foreach(HashMap.scala:221) at scala.collection.immutable.HashMap$HashTrieMap.foreach(HashMap.scala:428) at scala.collection.TraversableLike$WithFilter.map(TraversableLike.scala:682) at akka.serialization.Serialization.<init>(Serialization.scala:327) at akka.serialization.SerializationExtension$.createExtension(SerializationExtension.scala:15) at akka.serialization.SerializationExtension$.createExtension(SerializationExtension.scala:12) at akka.actor.ActorSystemImpl.registerExtension(ActorSystem.scala:913) at akka.actor.ActorSystemImpl$$anonfun$loadExtensions$1$1.apply(ActorSystem.scala:946) at akka.actor.ActorSystemImpl$$anonfun$loadExtensions$1$1.apply(ActorSystem.scala:944) at scala.collection.Iterator$class.foreach(Iterator.scala:891) at scala.collection.AbstractIterator.foreach(Iterator.scala:1334) at scala.collection.IterableLike$class.foreach(IterableLike.scala:72) at scala.collection.AbstractIterable.foreach(Iterable.scala:54) at akka.actor.ActorSystemImpl.loadExtensions$1(ActorSystem.scala:944) at akka.actor.ActorSystemImpl.loadExtensions(ActorSystem.scala:961) at akka.actor.ActorSystemImpl.liftedTree2$1(ActorSystem.scala:833) at akka.actor.ActorSystemImpl._start$lzycompute(ActorSystem.scala:823) at akka.actor.ActorSystemImpl._start(ActorSystem.scala:823) at akka.actor.ActorSystemImpl.start(ActorSystem.scala:842) at akka.actor.ActorSystem$.apply(ActorSystem.scala:246) at akka.actor.ActorSystem$.apply(ActorSystem.scala:289) at akka.actor.ActorSystem$.apply(ActorSystem.scala:234) at akka.actor.ActorSystem$.apply(ActorSystem.scala:225) at akka.actor.ActorSystem$.create(ActorSystem.scala:160) at akka.actor.ActorSystem.create(ActorSystem.scala) at de.eso.swarm.rest.client.akka.AkkaRestClient.<clinit>(AkkaRestClient.java:43) ... 12 more My application needs to initialize the AKKA ActorSystem because it uses an HTTP client that I have developed using akka-http and akka-stream. Here are the dependencies of my HTTP client: dependencies { compile project(':platform-sdk-java-core') testCompile project(':platform-sdk-java-testing') implementation group: 'com.typesafe.akka', name: 'akka-http_2.11', version: '10.1.2' implementation group: 'com.typesafe.akka', name: 'akka-stream_2.11', version: '2.5.11' implementation group: 'com.google.code.gson', name: 'gson', version: '2.8.4' implementation group: 'com.google.protobuf', name: 'protobuf-java', version: '3.5.1' testImplementation group: 'junit', name: 'junit', version: '4.12' } On the other hand, when I add the flink runtime to my runtime dependencies, everything works: dependencies { implementation group: 'org.apache.flink', name: 'flink-core', version: '1.4.2' implementation group: 'org.apache.flink', name: 'flink-java', version: '1.4.2' implementation group: 'org.apache.flink', name: 'flink-streaming-java_2.11', version: '1.4.2' implementation group: 'org.apache.flink', name: 'flink-connector-kafka-0.11_2.11', version: '1.4.2' } Relocation of AKKA did not solve the problem, because AKKA did no longer find its serialization classes. Using an older version of akka http and akka streams is also not an option, because the client won't compile in that case. Are the any other ideas? Thanks in advance Martin ---------------------------------------------------------------------------------- Martin Gäckler Entwicklung Schwarmdienste Im Auftrag der e.solutions GmbH Despagstr. 4a 85055 Ingolstadt Germany Registered Office: Despagstr. 4a 85055 Ingolstadt Germany Phone +49 8458 3332 145 e.solutions GmbH Managing Directors Uwe Reder, Dr. Riclef Schmidt-Clausen Register Court Ingolstadt HRB 5221