diff --git a/ccm-core/src/main/java/org/libreccm/categorization/CategoryMarshaller.java b/ccm-core/src/main/java/org/libreccm/categorization/CategoryMarshaller.java
index c5aaec025..2174c8bd5 100644
--- a/ccm-core/src/main/java/org/libreccm/categorization/CategoryMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/categorization/CategoryMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.categorization;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class CategoryMarshaller extends AbstractMarshaller<Category> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(Category portableObject) {
         categoryRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/security/GroupMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/GroupMarshaller.java
index 58afaab8f..e4c8dbce3 100644
--- a/ccm-core/src/main/java/org/libreccm/security/GroupMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/GroupMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.security;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class GroupMarshaller extends AbstractMarshaller<Group> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(Group portableObject) {
         groupRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/security/GroupMembershipMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/GroupMembershipMarshaller.java
index a8b8dd026..7c98a7335 100644
--- a/ccm-core/src/main/java/org/libreccm/security/GroupMembershipMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/GroupMembershipMarshaller.java
@@ -22,6 +22,7 @@ import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -38,6 +39,7 @@ public class GroupMembershipMarshaller extends AbstractMarshaller<GroupMembershi
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(GroupMembership portableObject) {
         if (portableObject.getMembershipId() == 0) {
             entityManager.persist(portableObject);
diff --git a/ccm-core/src/main/java/org/libreccm/security/PermissionMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/PermissionMarshaller.java
index 63f408535..94c30df62 100644
--- a/ccm-core/src/main/java/org/libreccm/security/PermissionMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/PermissionMarshaller.java
@@ -22,6 +22,7 @@ import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -38,6 +39,7 @@ public class PermissionMarshaller extends AbstractMarshaller<Permission> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(Permission portableObject) {
         if (portableObject.getPermissionId() == 0) {
             entityManager.persist(portableObject);
diff --git a/ccm-core/src/main/java/org/libreccm/security/RoleMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/RoleMarshaller.java
index 024302276..40423ee88 100644
--- a/ccm-core/src/main/java/org/libreccm/security/RoleMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/RoleMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.security;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class RoleMarshaller extends AbstractMarshaller<Role> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(Role portableObject) {
         roleRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/security/RoleMembershipMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/RoleMembershipMarshaller.java
index 10263bbcc..a98ee33ff 100644
--- a/ccm-core/src/main/java/org/libreccm/security/RoleMembershipMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/RoleMembershipMarshaller.java
@@ -22,6 +22,7 @@ import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -38,6 +39,7 @@ public class RoleMembershipMarshaller extends AbstractMarshaller<RoleMembership>
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(RoleMembership portableObject) {
         if (portableObject.getMembershipId() == 0) {
             entityManager.persist(portableObject);
diff --git a/ccm-core/src/main/java/org/libreccm/security/UserMarshaller.java b/ccm-core/src/main/java/org/libreccm/security/UserMarshaller.java
index 51b93cc16..450553d95 100644
--- a/ccm-core/src/main/java/org/libreccm/security/UserMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/security/UserMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.security;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class UserMarshaller extends AbstractMarshaller<User> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(User portableObject) {
         userRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/workflow/AssignableTaskMarshaller.java b/ccm-core/src/main/java/org/libreccm/workflow/AssignableTaskMarshaller.java
index ce452f808..b6010ad8f 100644
--- a/ccm-core/src/main/java/org/libreccm/workflow/AssignableTaskMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/workflow/AssignableTaskMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.workflow;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class AssignableTaskMarshaller extends AbstractMarshaller<AssignableTask>
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(AssignableTask portableObject) {
         assignableTaskRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/workflow/Task.java b/ccm-core/src/main/java/org/libreccm/workflow/Task.java
index 8303f7c31..7ff527165 100644
--- a/ccm-core/src/main/java/org/libreccm/workflow/Task.java
+++ b/ccm-core/src/main/java/org/libreccm/workflow/Task.java
@@ -18,20 +18,13 @@
  */
 package org.libreccm.workflow;
 
-import static org.libreccm.core.CoreConstants.*;
-
 import com.fasterxml.jackson.annotation.JsonBackReference;
-import com.fasterxml.jackson.annotation.JsonManagedReference;
+import com.fasterxml.jackson.annotation.JsonIdentityInfo;
+import com.fasterxml.jackson.annotation.ObjectIdGenerators;
 import org.libreccm.core.CcmObject;
 import org.libreccm.core.Identifiable;
 import org.libreccm.l10n.LocalizedString;
 
-import java.io.Serializable;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Objects;
-
 import javax.persistence.AssociationOverride;
 import javax.persistence.Column;
 import javax.persistence.Embedded;
@@ -52,6 +45,13 @@ import javax.persistence.NamedQuery;
 import javax.persistence.OneToMany;
 import javax.persistence.Table;
 import javax.validation.constraints.NotNull;
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+import static org.libreccm.core.CoreConstants.DB_SCHEMA;
 
 /**
  * A task is part of a workflow and represents a specific step in the creation
@@ -166,7 +166,9 @@ public class Task implements Identifiable, Serializable {
      * Tasks which the depends of this task.
      */
     @ManyToMany(mappedBy = "dependsOn")
-    @JsonManagedReference(value = "dependent-dependson")
+    @JsonIdentityInfo(
+            generator = ObjectIdGenerators.PropertyGenerator.class,
+            property = "taskId")
     private List<Task> dependentTasks;
 
     /**
@@ -179,7 +181,9 @@ public class Task implements Identifiable, Serializable {
                    @JoinColumn(name = "DEPENDS_ON_TASK_ID")},
                inverseJoinColumns = {
                    @JoinColumn(name = "DEPENDENT_TASK_ID")})
-    @JsonBackReference(value = "dependent-dependson")
+    @JsonIdentityInfo(
+            generator = ObjectIdGenerators.PropertyGenerator.class,
+            property = "taskId")
     private List<Task> dependsOn;
 
     /**
diff --git a/ccm-core/src/main/java/org/libreccm/workflow/TaskAssignmentMarshaller.java b/ccm-core/src/main/java/org/libreccm/workflow/TaskAssignmentMarshaller.java
index 5a39d987b..1df7c75dd 100644
--- a/ccm-core/src/main/java/org/libreccm/workflow/TaskAssignmentMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/workflow/TaskAssignmentMarshaller.java
@@ -22,6 +22,7 @@ import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -38,6 +39,7 @@ public class TaskAssignmentMarshaller extends AbstractMarshaller<TaskAssignment>
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(TaskAssignment portableObject) {
         if (portableObject.getTaskAssignmentId() == 0) {
             entityManager.persist(portableObject);
diff --git a/ccm-core/src/main/java/org/libreccm/workflow/WorkflowMarshaller.java b/ccm-core/src/main/java/org/libreccm/workflow/WorkflowMarshaller.java
index aece9259c..a6559c357 100644
--- a/ccm-core/src/main/java/org/libreccm/workflow/WorkflowMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/workflow/WorkflowMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.workflow;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -37,6 +38,7 @@ public class WorkflowMarshaller extends AbstractMarshaller<Workflow> {
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(Workflow portableObject) {
         workflowRepository.save(portableObject);
     }
diff --git a/ccm-core/src/main/java/org/libreccm/workflow/WorkflowTemplateMarshaller.java b/ccm-core/src/main/java/org/libreccm/workflow/WorkflowTemplateMarshaller.java
index 1cae65498..49f9119fe 100644
--- a/ccm-core/src/main/java/org/libreccm/workflow/WorkflowTemplateMarshaller.java
+++ b/ccm-core/src/main/java/org/libreccm/workflow/WorkflowTemplateMarshaller.java
@@ -21,6 +21,7 @@ package org.libreccm.workflow;
 import org.libreccm.portation.AbstractMarshaller;
 
 import javax.inject.Inject;
+import javax.transaction.Transactional;
 
 /**
  * @author <a href="mailto:tosmers@uni-bremen.de>Tobias Osmers</a>
@@ -38,6 +39,7 @@ public class WorkflowTemplateMarshaller extends
     }
 
     @Override
+    @Transactional(Transactional.TxType.REQUIRED)
     protected void insertIntoDb(WorkflowTemplate portableObject) {
         workflowTemplateRepository.save(portableObject);
     }