diff --git a/core/src/main/groovy/com/muwire/core/Event.groovy b/core/src/main/groovy/com/muwire/core/Event.groovy
new file mode 100644
index 00000000..4a9c0e94
--- /dev/null
+++ b/core/src/main/groovy/com/muwire/core/Event.groovy
@@ -0,0 +1,15 @@
+package com.muwire.core
+
+import java.util.concurrent.atomic.AtomicLong
+
+class Event {
+
+	private static final AtomicLong SEQ_NO = new AtomicLong();
+	final long seqNo
+	final long timestamp
+	
+	Event() {
+		seqNo = SEQ_NO.getAndIncrement()
+		timestamp = System.currentTimeMillis()
+	}
+}
diff --git a/core/src/main/groovy/com/muwire/core/files/FileHashedEvent.groovy b/core/src/main/groovy/com/muwire/core/files/FileHashedEvent.groovy
new file mode 100644
index 00000000..57d46237
--- /dev/null
+++ b/core/src/main/groovy/com/muwire/core/files/FileHashedEvent.groovy
@@ -0,0 +1,8 @@
+package com.muwire.core.files
+
+import com.muwire.core.Event
+
+class FileHashedEvent extends Event {
+
+	def sharedFile
+}
diff --git a/core/src/main/groovy/com/muwire/core/files/FileSharedEvent.groovy b/core/src/main/groovy/com/muwire/core/files/FileSharedEvent.groovy
new file mode 100644
index 00000000..e26e81bc
--- /dev/null
+++ b/core/src/main/groovy/com/muwire/core/files/FileSharedEvent.groovy
@@ -0,0 +1,8 @@
+package com.muwire.core.files
+
+import com.muwire.core.Event
+
+class FileSharedEvent extends Event {
+
+	File file
+}
diff --git a/core/src/main/groovy/com/muwire/core/files/HasherService.groovy b/core/src/main/groovy/com/muwire/core/files/HasherService.groovy
new file mode 100644
index 00000000..04fc9910
--- /dev/null
+++ b/core/src/main/groovy/com/muwire/core/files/HasherService.groovy
@@ -0,0 +1,5 @@
+package com.muwire.core.files
+
+class HasherService {
+
+}