diff --git a/src/main/java/mops/gruppen2/config/SwaggerConfig.java b/src/main/java/mops/gruppen2/config/SwaggerConfig.java
index 4c13329..fb3c81d 100644
--- a/src/main/java/mops/gruppen2/config/SwaggerConfig.java
+++ b/src/main/java/mops/gruppen2/config/SwaggerConfig.java
@@ -1,6 +1,5 @@
 package mops.gruppen2.config;
 
-import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Profile;
@@ -16,7 +15,6 @@ import java.util.Collections;
 
 @Profile("dev")
 @Configuration
-@EnableCaching
 @EnableSwagger2
 public class SwaggerConfig {
 
diff --git a/src/main/java/mops/gruppen2/domain/event/Event.java b/src/main/java/mops/gruppen2/domain/event/Event.java
index 84e563c..abb2ceb 100644
--- a/src/main/java/mops/gruppen2/domain/event/Event.java
+++ b/src/main/java/mops/gruppen2/domain/event/Event.java
@@ -11,6 +11,7 @@ import mops.gruppen2.domain.exception.BadArgumentException;
 import mops.gruppen2.domain.exception.EventException;
 import mops.gruppen2.domain.exception.IdMismatchException;
 import mops.gruppen2.domain.model.group.Group;
+import mops.gruppen2.infrastructure.GroupCache;
 
 import java.util.UUID;
 
@@ -31,7 +32,6 @@ import java.util.UUID;
 @NoArgsConstructor // Lombok needs a default constructor in the base class
 public abstract class Event {
 
-
     @JsonProperty("groupid")
     protected UUID groupid;
 
@@ -60,7 +60,7 @@ public abstract class Event {
         this.version = version;
     }
 
-    public Group apply(Group group) throws EventException {
+    public void apply(Group group, GroupCache cache) throws EventException {
         log.trace("Event wird angewendet:\t{}", this);
 
         if (version == 0) {
@@ -68,23 +68,32 @@ public abstract class Event {
         }
 
         checkGroupIdMatch(group.getId());
-        group.update(version);
+        group.updateVersion(version);
         applyEvent(group);
-
-        return group;
+        updateCache(cache, group);
     }
 
-    private void checkGroupIdMatch(UUID groupId) throws IdMismatchException {
+    private void checkGroupIdMatch(UUID groupid) throws IdMismatchException {
         // CreateGroupEvents müssen die Id erst initialisieren
         if (this instanceof CreateGroupEvent) {
             return;
         }
 
-        if (!groupid.equals(groupId)) {
+        if (!this.groupid.equals(groupid)) {
             throw new IdMismatchException("Das Event gehört zu einer anderen Gruppe");
         }
     }
 
+    private void updateCache(GroupCache cache, Group group) {
+        if (this instanceof CreateGroupEvent) {
+            cache.put(group);
+        }
+
+        if (this instanceof DestroyGroupEvent) {
+            cache.remove(group);
+        }
+    }
+
     protected abstract void applyEvent(Group group) throws EventException;
 
     @JsonIgnore
diff --git a/src/main/java/mops/gruppen2/domain/model/group/Group.java b/src/main/java/mops/gruppen2/domain/model/group/Group.java
index 5c407f1..b26fae3 100644
--- a/src/main/java/mops/gruppen2/domain/model/group/Group.java
+++ b/src/main/java/mops/gruppen2/domain/model/group/Group.java
@@ -10,14 +10,14 @@ import mops.gruppen2.domain.exception.LastAdminException;
 import mops.gruppen2.domain.exception.NoAccessException;
 import mops.gruppen2.domain.exception.UserAlreadyExistsException;
 import mops.gruppen2.domain.exception.UserNotFoundException;
-import mops.gruppen2.domain.helper.CommonHelper;
-import mops.gruppen2.domain.helper.ValidationHelper;
 import mops.gruppen2.domain.model.group.wrapper.Body;
 import mops.gruppen2.domain.model.group.wrapper.Description;
 import mops.gruppen2.domain.model.group.wrapper.Limit;
 import mops.gruppen2.domain.model.group.wrapper.Link;
 import mops.gruppen2.domain.model.group.wrapper.Parent;
 import mops.gruppen2.domain.model.group.wrapper.Title;
+import mops.gruppen2.domain.service.helper.CommonHelper;
+import mops.gruppen2.domain.service.helper.ValidationHelper;
 
 import javax.validation.Valid;
 import java.time.LocalDateTime;
@@ -73,6 +73,7 @@ public class Group {
 
     // ####################################### Members ###########################################
 
+
     public List<User> getMembers() {
         return SortHelper.sortByMemberRole(new ArrayList<>(memberships.values())).stream()
                          .map(Membership::getUser)
@@ -210,6 +211,10 @@ public class Group {
         return type == Type.LECTURE;
     }
 
+    public boolean hasParent() {
+        return !parent.isEmpty();
+    }
+
 
     // ######################################## Setters ##########################################
 
@@ -262,7 +267,7 @@ public class Group {
         this.link = link;
     }
 
-    public void update(long version) throws IdMismatchException {
+    public void updateVersion(long version) throws IdMismatchException {
         meta = meta.setVersion(version);
     }
 
@@ -310,4 +315,8 @@ public class Group {
                + (meta == null ? "meta: null" : meta.toString())
                + ")";
     }
+
+    public static Group EMPTY() {
+        return new Group();
+    }
 }
diff --git a/src/main/java/mops/gruppen2/domain/model/group/User.java b/src/main/java/mops/gruppen2/domain/model/group/User.java
index 63464ee..5fa6802 100644
--- a/src/main/java/mops/gruppen2/domain/model/group/User.java
+++ b/src/main/java/mops/gruppen2/domain/model/group/User.java
@@ -56,4 +56,8 @@ public class User {
     public String format() {
         return givenname + " " + familyname;
     }
+
+    public boolean isMember(Group group) {
+        return group.getMembers().contains(this);
+    }
 }
diff --git a/src/main/java/mops/gruppen2/domain/model/group/wrapper/Parent.java b/src/main/java/mops/gruppen2/domain/model/group/wrapper/Parent.java
index bd3d05d..e19cc6e 100644
--- a/src/main/java/mops/gruppen2/domain/model/group/wrapper/Parent.java
+++ b/src/main/java/mops/gruppen2/domain/model/group/wrapper/Parent.java
@@ -4,7 +4,7 @@ import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.ToString;
 import lombok.Value;
-import mops.gruppen2.domain.helper.CommonHelper;
+import mops.gruppen2.domain.service.helper.CommonHelper;
 
 import javax.validation.constraints.NotBlank;
 import javax.validation.constraints.NotNull;
diff --git a/src/main/java/mops/gruppen2/domain/service/EventStoreService.java b/src/main/java/mops/gruppen2/domain/service/EventStoreService.java
index 00f4d2d..8acb61d 100644
--- a/src/main/java/mops/gruppen2/domain/service/EventStoreService.java
+++ b/src/main/java/mops/gruppen2/domain/service/EventStoreService.java
@@ -3,39 +3,26 @@ package mops.gruppen2.domain.service;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
-import mops.gruppen2.aspect.annotation.TraceMethodCalls;
 import mops.gruppen2.domain.event.AddMemberEvent;
-import mops.gruppen2.domain.event.CreateGroupEvent;
 import mops.gruppen2.domain.event.Event;
 import mops.gruppen2.domain.event.EventType;
-import mops.gruppen2.domain.event.SetTypeEvent;
 import mops.gruppen2.domain.exception.BadPayloadException;
-import mops.gruppen2.domain.exception.InvalidInviteException;
-import mops.gruppen2.domain.helper.CommonHelper;
-import mops.gruppen2.domain.helper.JsonHelper;
-import mops.gruppen2.domain.model.group.Type;
+import mops.gruppen2.domain.service.helper.JsonHelper;
 import mops.gruppen2.persistance.EventRepository;
 import mops.gruppen2.persistance.dto.EventDTO;
 import org.springframework.stereotype.Service;
 
-import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
-import static mops.gruppen2.domain.event.EventType.CREATEGROUP;
 import static mops.gruppen2.domain.event.EventType.DESTROYGROUP;
-import static mops.gruppen2.domain.event.EventType.SETLINK;
-import static mops.gruppen2.domain.event.EventType.SETTYPE;
-import static mops.gruppen2.domain.helper.CommonHelper.eventTypesToString;
-import static mops.gruppen2.domain.helper.CommonHelper.uuidsToString;
+import static mops.gruppen2.domain.service.helper.CommonHelper.eventTypesToString;
 
 @Log4j2
 @RequiredArgsConstructor
 @Service
-@TraceMethodCalls
 public class EventStoreService {
 
     private final EventRepository eventStore;
@@ -77,12 +64,6 @@ public class EventStoreService {
     //########################################### DTOs ###########################################
 
 
-    private static List<EventDTO> getDTOsFromEvents(List<Event> events) {
-        return events.stream()
-                     .map(EventStoreService::getDTOFromEvent)
-                     .collect(Collectors.toList());
-    }
-
     /**
      * Erzeugt aus einem Event Objekt ein EventDTO Objekt.
      *
@@ -132,81 +113,6 @@ public class EventStoreService {
     // ######################################## QUERIES ##########################################
 
 
-    List<Event> findGroupEvents(UUID groupId) {
-        return getEventsFromDTOs(eventStore.findEventDTOsByGroup(Collections.singletonList(groupId.toString())));
-    }
-
-    /**
-     * Sucht alle Events, welche zu einer der übergebenen Gruppen gehören.
-     *
-     * @param groupIds Liste an IDs
-     *
-     * @return Liste an Events
-     */
-    List<Event> findGroupEvents(List<UUID> groupIds) {
-        List<EventDTO> eventDTOS = new ArrayList<>();
-
-        for (UUID groupId : groupIds) {
-            eventDTOS.addAll(eventStore.findEventDTOsByGroup(Collections.singletonList(groupId.toString())));
-        }
-
-        return getEventsFromDTOs(eventDTOS);
-    }
-
-    /**
-     * Findet alle Events zu Gruppen, welche seit dem neuen Status verändert wurden.
-     *
-     * @param status Die Id des zuletzt gespeicherten Events
-     *
-     * @return Liste von neuen und alten Events
-     */
-    List<UUID> findChangedGroups(long status) {
-        List<String> changedGroupIds = eventStore.findGroupIdsWhereEventIdGreaterThanStatus(status);
-
-        log.debug("Seit Event {} haben sich {} Gruppen geändert!", status, changedGroupIds.size());
-
-        return CommonHelper.stringsToUUID(changedGroupIds);
-    }
-
-    /**
-     * Liefert Gruppen-Ids von existierenden (ungelöschten) Gruppen.
-     *
-     * @return GruppenIds (UUID) als Liste
-     */
-    List<UUID> findExistingGroupIds() {
-        List<Event> createEvents = findLatestEventsFromGroupsByType(CREATEGROUP,
-                                                                    DESTROYGROUP);
-
-        return createEvents.stream()
-                           .filter(event -> event instanceof CreateGroupEvent)
-                           .map(Event::getGroupid)
-                           .collect(Collectors.toList());
-    }
-
-    public List<UUID> findPublicGroupIds() {
-        List<UUID> groups = findExistingGroupIds();
-        List<Event> typeEvents = findLatestEventsFromGroupsByType(SETTYPE);
-
-        typeEvents.removeIf(event -> ((SetTypeEvent) event).getType() == Type.PRIVATE);
-        typeEvents.removeIf(event -> !groups.contains(event.getGroupid()));
-
-        return typeEvents.stream()
-                         .map(Event::getGroupid)
-                         .collect(Collectors.toList());
-    }
-
-    public List<UUID> findLectureGroupIds() {
-        List<UUID> groups = findExistingGroupIds();
-        List<Event> typeEvents = findLatestEventsFromGroupsByType(SETTYPE);
-
-        typeEvents.removeIf(event -> ((SetTypeEvent) event).getType() != Type.LECTURE);
-        typeEvents.removeIf(event -> !groups.contains(event.getGroupid()));
-
-        return typeEvents.stream()
-                         .map(Event::getGroupid)
-                         .collect(Collectors.toList());
-    }
-
     /**
      * Liefert Gruppen-Ids von existierenden (ungelöschten) Gruppen, in welchen der User teilnimmt.
      *
@@ -234,20 +140,6 @@ public class EventStoreService {
                          .collect(Collectors.toList());
     }
 
-    public UUID findGroupByLink(String link) {
-        List<Event> groupEvents = findEventsByType(eventTypesToString(SETLINK));
-
-        if (groupEvents.size() > 1) {
-            throw new InvalidInviteException("Es existieren mehrere Gruppen mit demselben Link.");
-        }
-
-        if (groupEvents.isEmpty()) {
-            throw new InvalidInviteException("Link nicht gefunden.");
-        }
-
-        return groupEvents.get(0).getGroupid();
-    }
-
 
     // #################################### SIMPLE QUERIES #######################################
 
@@ -262,23 +154,10 @@ public class EventStoreService {
             return eventStore.findMaxEventId();
         } catch (NullPointerException e) {
             log.debug("Keine Events vorhanden!");
-            return 1;
+            return 0;
         }
     }
 
-    List<Event> findEventsByType(String... types) {
-        return getEventsFromDTOs(eventStore.findEventDTOsByType(Arrays.asList(types)));
-    }
-
-    List<Event> findEventsByType(String type) {
-        return getEventsFromDTOs(eventStore.findEventDTOsByType(Collections.singletonList(type)));
-    }
-
-    List<Event> findEventsByGroupAndType(List<UUID> groupIds, String... types) {
-        return getEventsFromDTOs(eventStore.findEventDTOsByGroupAndType(uuidsToString(groupIds),
-                                                                        Arrays.asList(types)));
-    }
-
     /**
      * Sucht zu jeder Gruppe das letzte Add- oder DeleteUserEvent heraus, welches den übergebenen User betrifft.
      *
@@ -301,4 +180,12 @@ public class EventStoreService {
     private List<Event> findLatestEventsFromGroupsByType(EventType... types) {
         return getEventsFromDTOs(eventStore.findLatestEventDTOsPartitionedByGroupByType(Arrays.asList(eventTypesToString(types))));
     }
+
+    public List<Event> findAllEvents() {
+        return getEventsFromDTOs(eventStore.findAllEvents());
+    }
+
+    public List<Event> findNewEvents(long version, long maxid) {
+        return getEventsFromDTOs(eventStore.findNewEvents(version, maxid));
+    }
 }
diff --git a/src/main/java/mops/gruppen2/domain/service/GroupService.java b/src/main/java/mops/gruppen2/domain/service/GroupService.java
index 477da7c..612e627 100644
--- a/src/main/java/mops/gruppen2/domain/service/GroupService.java
+++ b/src/main/java/mops/gruppen2/domain/service/GroupService.java
@@ -2,7 +2,6 @@ package mops.gruppen2.domain.service;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
-import mops.gruppen2.aspect.annotation.TraceMethodCalls;
 import mops.gruppen2.domain.event.AddMemberEvent;
 import mops.gruppen2.domain.event.CreateGroupEvent;
 import mops.gruppen2.domain.event.DestroyGroupEvent;
@@ -16,7 +15,6 @@ import mops.gruppen2.domain.event.SetTitleEvent;
 import mops.gruppen2.domain.event.SetTypeEvent;
 import mops.gruppen2.domain.event.UpdateRoleEvent;
 import mops.gruppen2.domain.exception.EventException;
-import mops.gruppen2.domain.helper.ValidationHelper;
 import mops.gruppen2.domain.model.group.Group;
 import mops.gruppen2.domain.model.group.Role;
 import mops.gruppen2.domain.model.group.Type;
@@ -26,6 +24,8 @@ import mops.gruppen2.domain.model.group.wrapper.Limit;
 import mops.gruppen2.domain.model.group.wrapper.Link;
 import mops.gruppen2.domain.model.group.wrapper.Parent;
 import mops.gruppen2.domain.model.group.wrapper.Title;
+import mops.gruppen2.domain.service.helper.ValidationHelper;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.springframework.stereotype.Service;
 
 import java.time.LocalDateTime;
@@ -37,11 +37,11 @@ import java.util.UUID;
  * Es werden übergebene Gruppen bearbeitet und dementsprechend Events erzeugt und gespeichert.
  */
 @Log4j2
-@TraceMethodCalls
 @RequiredArgsConstructor
 @Service
 public class GroupService {
 
+    private final GroupCache groupCache;
     private final EventStoreService eventStoreService;
 
     // ################################# GRUPPE ERSTELLEN ########################################
@@ -266,7 +266,7 @@ public class GroupService {
 
     private void applyAndSave(Group group, Event event) throws EventException {
         event.init(group.version() + 1);
-        event.apply(group);
+        event.apply(group, groupCache);
 
         eventStoreService.saveEvent(event);
     }
diff --git a/src/main/java/mops/gruppen2/domain/service/ProjectionService.java b/src/main/java/mops/gruppen2/domain/service/ProjectionService.java
deleted file mode 100644
index 1338eef..0000000
--- a/src/main/java/mops/gruppen2/domain/service/ProjectionService.java
+++ /dev/null
@@ -1,215 +0,0 @@
-package mops.gruppen2.domain.service;
-
-import lombok.RequiredArgsConstructor;
-import lombok.extern.log4j.Log4j2;
-import mops.gruppen2.domain.event.Event;
-import mops.gruppen2.domain.exception.EventException;
-import mops.gruppen2.domain.exception.GroupNotFoundException;
-import mops.gruppen2.domain.helper.CommonHelper;
-import mops.gruppen2.domain.model.group.Group;
-import org.springframework.cache.annotation.Cacheable;
-import org.springframework.stereotype.Service;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.UUID;
-
-/**
- * Liefert verschiedene Projektionen auf Gruppen.
- * Benötigt ausschließlich den EventStoreService.
- */
-@Log4j2
-@RequiredArgsConstructor
-@Service
-public class ProjectionService {
-
-    private final EventStoreService eventStoreService;
-
-
-    // ################################## STATISCHE PROJEKTIONEN #################################
-
-
-    /**
-     * Projiziert Events, geht aber davon aus, dass alle zu derselben Gruppe gehören.
-     *
-     * @param events Eventliste
-     *
-     * @return Eine projizierte Gruppe
-     *
-     * @throws EventException Projektionsfehler, z.B. falls Events von verschiedenen Gruppen übergeben werden
-     */
-    private static Group projectGroupByEvents(List<Event> events) throws EventException {
-        if (events.isEmpty()) {
-            throw new GroupNotFoundException(ProjectionService.class.toString());
-        }
-
-        Group group = new Group();
-
-        events.forEach(event -> event.apply(group));
-
-        return group;
-    }
-
-    /**
-     * Konstruiert Gruppen aus einer Liste von Events.
-     *
-     * @param events Liste an Events
-     *
-     * @return Liste an Projizierten Gruppen
-     *
-     * @throws EventException Projektionsfehler
-     */
-    public static List<Group> projectGroupsByEvents(List<Event> events) throws EventException {
-        Map<UUID, Group> groupMap = new HashMap<>();
-
-        events.forEach(event -> event.apply(getOrCreateGroup(groupMap, event.getGroupid())));
-
-        return new ArrayList<>(groupMap.values());
-    }
-
-    /**
-     * Gibt die Gruppe mit der richtigen Id aus der übergebenen Map wieder, existiert diese nicht
-     * wird die Gruppe erstellt und der Map hizugefügt.
-     *
-     * @param groups  Map aus GruppenIds und Gruppen
-     * @param groupId Die Id der Gruppe, die zurückgegeben werden soll
-     *
-     * @return Die gesuchte Gruppe
-     */
-    private static Group getOrCreateGroup(Map<UUID, Group> groups, UUID groupId) {
-        if (!groups.containsKey(groupId)) {
-            groups.put(groupId, new Group());
-        }
-
-        return groups.get(groupId);
-    }
-
-
-    // ############################### PROJEKTIONEN MIT DATENBANK ################################
-
-
-    /**
-     * Gibt die Gruppe zurück, die zu der übergebenen Id passt.
-     * Enthält alle verfügbaren Informationen, also auch User (langsam).
-     * Gibt eine leere Gruppe zurück, falls die Id leer ist.
-     *
-     * @param groupId Die Id der gesuchten Gruppe
-     *
-     * @return Die gesuchte Gruppe
-     *
-     * @throws GroupNotFoundException Wenn die Gruppe nicht gefunden wird
-     */
-    public Group projectGroupById(UUID groupId) throws GroupNotFoundException {
-        try {
-            List<Event> events = eventStoreService.findGroupEvents(groupId);
-            return projectGroupByEvents(events);
-        } catch (Exception e) {
-            log.error("Gruppe {} wurde nicht gefunden!", groupId.toString(), e);
-            throw new GroupNotFoundException(groupId + ": " + ProjectionService.class);
-        }
-    }
-
-    public Group projectParent(UUID parent) {
-        if (CommonHelper.uuidIsEmpty(parent)) {
-            return new Group();
-        }
-
-        return projectGroupById(parent);
-    }
-
-    public List<Group> projectGroupsByIds(List<UUID> groupids) {
-        List<Event> events = eventStoreService.findGroupEvents(groupids);
-
-        return projectGroupsByEvents(events);
-    }
-
-    /**
-     * Projiziert Gruppen, welche sich seit einer übergebenen eventId geändert haben.
-     * Die Gruppen werden dabei vollständig konstruiert.
-     *
-     * @param status Letzte bekannte eventId
-     *
-     * @return Liste an Gruppen
-     */
-    public List<Group> projectChangedGroups(long status) {
-        List<UUID> changedids = eventStoreService.findChangedGroups(status);
-
-        return projectGroupsByIds(changedids);
-    }
-
-    /**
-     * Projiziert öffentliche Gruppen.
-     * Die Gruppen enthalten Metainformationen: Titel, Beschreibung und MaxUserAnzahl.
-     * Außerdem wird noch beachtet, ob der eingeloggte User bereits in entsprechenden Gruppen mitglied ist.
-     *
-     * @return Liste von projizierten Gruppen
-     *
-     * @throws EventException Projektionsfehler
-     */
-    @Cacheable("groups")
-    public List<Group> projectPublicGroups() throws EventException {
-        List<UUID> groupIds = eventStoreService.findPublicGroupIds();
-
-        if (groupIds.isEmpty()) {
-            return Collections.emptyList();
-        }
-
-        return projectGroupsByIds(groupIds);
-    }
-
-    /**
-     * Projiziert Vorlesungen.
-     * Projektionen enthalten nur Metainformationen: Titel.
-     *
-     * @return Liste von Veranstaltungen
-     */
-    @Cacheable("groups")
-    public List<Group> projectLectures() {
-        List<UUID> groupIds = eventStoreService.findLectureGroupIds();
-
-        if (groupIds.isEmpty()) {
-            return Collections.emptyList();
-        }
-
-        return projectGroupsByIds(groupIds);
-    }
-
-    /**
-     * Projiziert Gruppen, in welchen der User aktuell teilnimmt.
-     * Die Gruppen enthalten nur Metainformationen: Titel und Beschreibung.
-     *
-     * @param userid Die Id
-     *
-     * @return Liste aus Gruppen
-     */
-    @Cacheable("groups")
-    public List<Group> projectUserGroups(String userid) {
-        List<UUID> groupIds = eventStoreService.findExistingUserGroups(userid);
-
-        if (groupIds.isEmpty()) {
-            return Collections.emptyList();
-        }
-
-        return projectGroupsByIds(groupIds);
-    }
-
-    /**
-     * Entfernt alle Gruppen, in welchen ein User teilnimmt, aus einer Gruppenliste.
-     *
-     * @param groups Gruppenliste, aus der entfernt wird
-     * @param userid User, welcher teilnimmt
-     */
-    void removeUserGroups(List<Group> groups, String userid) {
-        List<UUID> userGroups = eventStoreService.findExistingUserGroups(userid);
-
-        groups.removeIf(group -> userGroups.contains(group.getId()));
-    }
-
-    public Group projectGroupByLink(String link) {
-        return projectGroupById(eventStoreService.findGroupByLink(link));
-    }
-}
-
diff --git a/src/main/java/mops/gruppen2/domain/service/SearchService.java b/src/main/java/mops/gruppen2/domain/service/SearchService.java
index dcb5228..f87bf1b 100644
--- a/src/main/java/mops/gruppen2/domain/service/SearchService.java
+++ b/src/main/java/mops/gruppen2/domain/service/SearchService.java
@@ -1,24 +1,21 @@
 package mops.gruppen2.domain.service;
 
+import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.domain.exception.EventException;
 import mops.gruppen2.domain.model.group.Group;
-import mops.gruppen2.domain.model.group.SortHelper;
-import org.springframework.cache.annotation.Cacheable;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.springframework.stereotype.Service;
 
 import java.util.List;
 import java.util.stream.Collectors;
 
 @Service
+@RequiredArgsConstructor
 @Log4j2
 public class SearchService {
 
-    private final ProjectionService projectionService;
-
-    public SearchService(ProjectionService projectionService) {
-        this.projectionService = projectionService;
-    }
+    private final GroupCache groupCache;
 
     /**
      * Filtert alle öffentliche Gruppen nach dem Suchbegriff und gibt diese als sortierte Liste zurück.
@@ -31,13 +28,11 @@ public class SearchService {
      *
      * @throws EventException Projektionsfehler
      */
-    @Cacheable("groups")
+    //TODO: search in lectures
     public List<Group> searchPublicGroups(String search, String principal) {
-        List<Group> groups = projectionService.projectPublicGroups();
-        System.out.println(groups);
-        projectionService.removeUserGroups(groups, principal);
-        System.out.println(groups);
-        SortHelper.sortByGroupType(groups);
+        List<Group> groups = groupCache.publics();
+
+        groups = removeUserGroups(groups, principal);
 
         if (search.isEmpty()) {
             return groups;
@@ -50,4 +45,10 @@ public class SearchService {
                      .collect(Collectors.toList());
     }
 
+    private static List<Group> removeUserGroups(List<Group> groups, String principal) {
+        return groups.stream()
+                     .filter(group -> !group.isMember(principal))
+                     .collect(Collectors.toList());
+    }
+
 }
diff --git a/src/main/java/mops/gruppen2/domain/helper/APIHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/APIHelper.java
similarity index 80%
rename from src/main/java/mops/gruppen2/domain/helper/APIHelper.java
rename to src/main/java/mops/gruppen2/domain/service/helper/APIHelper.java
index 5da7990..39e7569 100644
--- a/src/main/java/mops/gruppen2/domain/helper/APIHelper.java
+++ b/src/main/java/mops/gruppen2/domain/service/helper/APIHelper.java
@@ -1,10 +1,10 @@
-package mops.gruppen2.domain.helper;
+package mops.gruppen2.domain.service.helper;
 
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.domain.model.group.Group;
-import mops.gruppen2.web.api.GroupRequestWrapper;
+import mops.gruppen2.infrastructure.api.GroupRequestWrapper;
 
 import java.util.List;
 
diff --git a/src/main/java/mops/gruppen2/domain/helper/CommonHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/CommonHelper.java
similarity index 96%
rename from src/main/java/mops/gruppen2/domain/helper/CommonHelper.java
rename to src/main/java/mops/gruppen2/domain/service/helper/CommonHelper.java
index 6e833d8..5ac0ed1 100644
--- a/src/main/java/mops/gruppen2/domain/helper/CommonHelper.java
+++ b/src/main/java/mops/gruppen2/domain/service/helper/CommonHelper.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.domain.helper;
+package mops.gruppen2.domain.service.helper;
 
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
diff --git a/src/main/java/mops/gruppen2/domain/helper/CsvHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/CsvHelper.java
similarity index 97%
rename from src/main/java/mops/gruppen2/domain/helper/CsvHelper.java
rename to src/main/java/mops/gruppen2/domain/service/helper/CsvHelper.java
index 5a43b85..c087540 100644
--- a/src/main/java/mops/gruppen2/domain/helper/CsvHelper.java
+++ b/src/main/java/mops/gruppen2/domain/service/helper/CsvHelper.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.domain.helper;
+package mops.gruppen2.domain.service.helper;
 
 import com.fasterxml.jackson.databind.ObjectReader;
 import com.fasterxml.jackson.dataformat.csv.CsvMapper;
diff --git a/src/main/java/mops/gruppen2/domain/helper/JsonHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/JsonHelper.java
similarity index 97%
rename from src/main/java/mops/gruppen2/domain/helper/JsonHelper.java
rename to src/main/java/mops/gruppen2/domain/service/helper/JsonHelper.java
index 614e929..b66c57f 100644
--- a/src/main/java/mops/gruppen2/domain/helper/JsonHelper.java
+++ b/src/main/java/mops/gruppen2/domain/service/helper/JsonHelper.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.domain.helper;
+package mops.gruppen2.domain.service.helper;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
diff --git a/src/main/java/mops/gruppen2/domain/service/helper/ProjectionHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/ProjectionHelper.java
new file mode 100644
index 0000000..b01b1aa
--- /dev/null
+++ b/src/main/java/mops/gruppen2/domain/service/helper/ProjectionHelper.java
@@ -0,0 +1,49 @@
+package mops.gruppen2.domain.service.helper;
+
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import lombok.extern.log4j.Log4j2;
+import mops.gruppen2.domain.event.Event;
+import mops.gruppen2.domain.model.group.Group;
+import mops.gruppen2.infrastructure.GroupCache;
+
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+/**
+ * Liefert verschiedene Projektionen auf Gruppen.
+ * Benötigt ausschließlich den EventStoreService.
+ */
+@Log4j2
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public final class ProjectionHelper {
+
+    public static void project(Map<UUID, Group> groups, List<Event> events, GroupCache cache) {
+        if (events.isEmpty()) {
+            return;
+        }
+
+        log.trace(groups);
+        log.trace(events);
+
+        events.forEach(event -> event.apply(getOrCreateGroup(groups, event.getGroupid()), cache));
+    }
+
+    /**
+     * Gibt die Gruppe mit der richtigen Id aus der übergebenen Map wieder, existiert diese nicht
+     * wird die Gruppe erstellt und der Map hizugefügt.
+     *
+     * @param groups  Map aus GruppenIds und Gruppen
+     * @param groupId Die Id der Gruppe, die zurückgegeben werden soll
+     *
+     * @return Die gesuchte Gruppe
+     */
+    private static Group getOrCreateGroup(Map<UUID, Group> groups, UUID groupId) {
+        if (!groups.containsKey(groupId)) {
+            groups.put(groupId, new Group());
+        }
+
+        return groups.get(groupId);
+    }
+}
diff --git a/src/main/java/mops/gruppen2/domain/helper/ValidationHelper.java b/src/main/java/mops/gruppen2/domain/service/helper/ValidationHelper.java
similarity index 98%
rename from src/main/java/mops/gruppen2/domain/helper/ValidationHelper.java
rename to src/main/java/mops/gruppen2/domain/service/helper/ValidationHelper.java
index 02cdc2e..22942bd 100644
--- a/src/main/java/mops/gruppen2/domain/helper/ValidationHelper.java
+++ b/src/main/java/mops/gruppen2/domain/service/helper/ValidationHelper.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.domain.helper;
+package mops.gruppen2.domain.service.helper;
 
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
diff --git a/src/main/java/mops/gruppen2/infrastructure/ApplicationInit.java b/src/main/java/mops/gruppen2/infrastructure/ApplicationInit.java
new file mode 100644
index 0000000..4c91b4e
--- /dev/null
+++ b/src/main/java/mops/gruppen2/infrastructure/ApplicationInit.java
@@ -0,0 +1,18 @@
+package mops.gruppen2.infrastructure;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+@RequiredArgsConstructor
+@Component
+public class ApplicationInit {
+
+    private final GroupCache groupCache;
+
+    @EventListener(ApplicationReadyEvent.class)
+    public void init() {
+        groupCache.init();
+    }
+}
diff --git a/src/main/java/mops/gruppen2/infrastructure/GroupCache.java b/src/main/java/mops/gruppen2/infrastructure/GroupCache.java
new file mode 100644
index 0000000..16044be
--- /dev/null
+++ b/src/main/java/mops/gruppen2/infrastructure/GroupCache.java
@@ -0,0 +1,79 @@
+package mops.gruppen2.infrastructure;
+
+import lombok.RequiredArgsConstructor;
+import mops.gruppen2.domain.exception.GroupNotFoundException;
+import mops.gruppen2.domain.model.group.Group;
+import mops.gruppen2.domain.service.EventStoreService;
+import mops.gruppen2.domain.service.helper.ProjectionHelper;
+import org.springframework.context.annotation.Scope;
+import org.springframework.stereotype.Component;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+@RequiredArgsConstructor
+@Component
+@Scope("singleton")
+public class GroupCache {
+
+    private final EventStoreService eventStoreService;
+
+    private final Map<UUID, Group> groups = new HashMap<>();
+
+    public void init() {
+        long maxid = eventStoreService.findMaxEventId();
+        ProjectionHelper.project(groups, eventStoreService.findNewEvents(0, maxid), this);
+    }
+
+    public void put(Group group) {
+        groups.put(group.getId(), group);
+    }
+
+    public void remove(Group group) {
+        groups.remove(group.getId());
+    }
+
+    // Getters
+
+    public Group group(UUID groupid) {
+        if (!groups.containsKey(groupid)) {
+            throw new GroupNotFoundException("Gruppe ist nicht im Cache.");
+        }
+
+        return groups.get(groupid);
+    }
+
+    public Group group(String link) {
+        return groups.values().stream()
+                     .filter(group -> group.getLink().equals(link))
+                     .findFirst()
+                     .orElseThrow(() -> new GroupNotFoundException("Link nicht im Cache."));
+    }
+
+    public List<Group> userGroups(String userid) {
+        return groups.values().stream()
+                     .filter(group -> group.isMember(userid))
+                     .collect(Collectors.toUnmodifiableList());
+    }
+
+    public List<Group> publics() {
+        return groups.values().stream()
+                     .filter(Group::isPublic)
+                     .collect(Collectors.toUnmodifiableList());
+    }
+
+    public List<Group> privates() {
+        return groups.values().stream()
+                     .filter(Group::isPrivate)
+                     .collect(Collectors.toUnmodifiableList());
+    }
+
+    public List<Group> lectures() {
+        return groups.values().stream()
+                     .filter(Group::isLecture)
+                     .collect(Collectors.toUnmodifiableList());
+    }
+}
diff --git a/src/main/java/mops/gruppen2/web/ModelAttributeControllerAdvice.java b/src/main/java/mops/gruppen2/infrastructure/ModelAttributeControllerAdvice.java
similarity index 89%
rename from src/main/java/mops/gruppen2/web/ModelAttributeControllerAdvice.java
rename to src/main/java/mops/gruppen2/infrastructure/ModelAttributeControllerAdvice.java
index 71c432f..17b81ed 100644
--- a/src/main/java/mops/gruppen2/web/ModelAttributeControllerAdvice.java
+++ b/src/main/java/mops/gruppen2/infrastructure/ModelAttributeControllerAdvice.java
@@ -1,5 +1,6 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure;
 
+import lombok.RequiredArgsConstructor;
 import mops.gruppen2.domain.Account;
 import mops.gruppen2.domain.model.group.Role;
 import mops.gruppen2.domain.model.group.Type;
@@ -9,9 +10,12 @@ import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ModelAttribute;
 
+@RequiredArgsConstructor
 @ControllerAdvice
 public class ModelAttributeControllerAdvice {
 
+    private final GroupCache groupCache;
+
     // Add modelAttributes before each @RequestMapping
     @ModelAttribute
     public void modelAttributes(KeycloakAuthenticationToken token,
diff --git a/src/main/java/mops/gruppen2/web/api/GroupRequestWrapper.java b/src/main/java/mops/gruppen2/infrastructure/api/GroupRequestWrapper.java
similarity index 89%
rename from src/main/java/mops/gruppen2/web/api/GroupRequestWrapper.java
rename to src/main/java/mops/gruppen2/infrastructure/api/GroupRequestWrapper.java
index d8e0680..e4d32a2 100644
--- a/src/main/java/mops/gruppen2/web/api/GroupRequestWrapper.java
+++ b/src/main/java/mops/gruppen2/infrastructure/api/GroupRequestWrapper.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.web.api;
+package mops.gruppen2.infrastructure.api;
 
 import lombok.AllArgsConstructor;
 import lombok.Getter;
diff --git a/src/main/java/mops/gruppen2/web/APIController.java b/src/main/java/mops/gruppen2/infrastructure/controller/APIController.java
similarity index 79%
rename from src/main/java/mops/gruppen2/web/APIController.java
rename to src/main/java/mops/gruppen2/infrastructure/controller/APIController.java
index 0a8dc5c..662bf99 100644
--- a/src/main/java/mops/gruppen2/web/APIController.java
+++ b/src/main/java/mops/gruppen2/infrastructure/controller/APIController.java
@@ -1,4 +1,4 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure.controller;
 
 
 import io.swagger.annotations.ApiOperation;
@@ -6,12 +6,8 @@ import io.swagger.annotations.ApiParam;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.aspect.annotation.TraceMethodCalls;
-import mops.gruppen2.domain.helper.APIHelper;
-import mops.gruppen2.domain.helper.CommonHelper;
-import mops.gruppen2.domain.model.group.Group;
 import mops.gruppen2.domain.service.EventStoreService;
-import mops.gruppen2.domain.service.ProjectionService;
-import mops.gruppen2.web.api.GroupRequestWrapper;
+import mops.gruppen2.domain.service.helper.CommonHelper;
 import org.springframework.security.access.annotation.Secured;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
@@ -19,7 +15,6 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 import java.util.List;
-import java.util.UUID;
 
 /**
  * Api zum Datenabgleich.
@@ -31,8 +26,9 @@ import java.util.UUID;
 @RequestMapping("/gruppen2/api")
 public class APIController {
 
+    //TODO: redo api
+
     private final EventStoreService eventStoreService;
-    private final ProjectionService projectionService;
 
     /**
      * Erzeugt eine Liste aus Gruppen, welche sich seit einer übergebenen Event-Id geändert haben.
@@ -40,15 +36,15 @@ public class APIController {
      *
      * @param eventId Die Event-ID, welche der Anfragesteller beim letzten Aufruf erhalten hat
      */
-    @GetMapping("/update/{id}")
+    /*@GetMapping("/update/{id}")
     @Secured("ROLE_api_user")
     @ApiOperation("Gibt veränderte Gruppen zurück")
     public GroupRequestWrapper getApiUpdate(@ApiParam("Letzte gespeicherte EventId des Anfragestellers")
                                             @PathVariable("id") long eventId) {
 
         return APIHelper.wrap(eventStoreService.findMaxEventId(),
-                              projectionService.projectChangedGroups(eventId));
-    }
+                              projectionHelper.projectChangedGroups(eventId));
+    }*/
 
     /**
      * Gibt die Gruppen-IDs von Gruppen, in welchen der übergebene Nutzer teilnimmt, zurück.
@@ -65,13 +61,13 @@ public class APIController {
     /**
      * Konstruiert eine einzelne, vollständige Gruppe.
      */
-    @GetMapping("/group/{id}")
+    /*@GetMapping("/group/{id}")
     @Secured("ROLE_api_user")
     @ApiOperation("Gibt die Gruppe mit der als Parameter mitgegebenden groupId zurück")
     public Group getApiGroup(@ApiParam("Gruppen-Id der gefordeten Gruppe")
                              @PathVariable("id") String groupId) {
 
-        return projectionService.projectGroupById(UUID.fromString(groupId));
-    }
+        return projectionHelper.projectGroupById(UUID.fromString(groupId));
+    }*/
 
 }
diff --git a/src/main/java/mops/gruppen2/web/GroupCreationController.java b/src/main/java/mops/gruppen2/infrastructure/controller/GroupCreationController.java
similarity index 87%
rename from src/main/java/mops/gruppen2/web/GroupCreationController.java
rename to src/main/java/mops/gruppen2/infrastructure/controller/GroupCreationController.java
index af56d77..84d4e1e 100644
--- a/src/main/java/mops/gruppen2/web/GroupCreationController.java
+++ b/src/main/java/mops/gruppen2/infrastructure/controller/GroupCreationController.java
@@ -1,10 +1,8 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure.controller;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.aspect.annotation.TraceMethodCalls;
-import mops.gruppen2.domain.helper.CsvHelper;
-import mops.gruppen2.domain.helper.ValidationHelper;
 import mops.gruppen2.domain.model.group.Group;
 import mops.gruppen2.domain.model.group.Type;
 import mops.gruppen2.domain.model.group.User;
@@ -13,9 +11,10 @@ import mops.gruppen2.domain.model.group.wrapper.Limit;
 import mops.gruppen2.domain.model.group.wrapper.Parent;
 import mops.gruppen2.domain.model.group.wrapper.Title;
 import mops.gruppen2.domain.service.GroupService;
-import mops.gruppen2.domain.service.ProjectionService;
+import mops.gruppen2.domain.service.helper.CsvHelper;
+import mops.gruppen2.domain.service.helper.ValidationHelper;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.keycloak.adapters.springsecurity.token.KeycloakAuthenticationToken;
-import org.springframework.cache.annotation.CacheEvict;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -35,21 +34,20 @@ import javax.validation.Valid;
 @RequestMapping("/gruppen2")
 public class GroupCreationController {
 
+    private final GroupCache groupCache;
     private final GroupService groupService;
-    private final ProjectionService projectionService;
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @GetMapping("/create")
     public String getCreate(Model model) {
 
-        model.addAttribute("lectures", projectionService.projectLectures());
+        model.addAttribute("lectures", groupCache.lectures());
 
         return "create";
     }
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/create")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postCreateOrga(KeycloakAuthenticationToken token,
                                  @RequestParam("type") Type type,
                                  @RequestParam("parent") @Valid Parent parent,
diff --git a/src/main/java/mops/gruppen2/web/GroupDetailsController.java b/src/main/java/mops/gruppen2/infrastructure/controller/GroupDetailsController.java
similarity index 81%
rename from src/main/java/mops/gruppen2/web/GroupDetailsController.java
rename to src/main/java/mops/gruppen2/infrastructure/controller/GroupDetailsController.java
index 58c3131..7aa5879 100644
--- a/src/main/java/mops/gruppen2/web/GroupDetailsController.java
+++ b/src/main/java/mops/gruppen2/infrastructure/controller/GroupDetailsController.java
@@ -1,19 +1,18 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure.controller;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.aspect.annotation.TraceMethodCalls;
-import mops.gruppen2.domain.helper.CsvHelper;
-import mops.gruppen2.domain.helper.ValidationHelper;
 import mops.gruppen2.domain.model.group.Group;
 import mops.gruppen2.domain.model.group.User;
 import mops.gruppen2.domain.model.group.wrapper.Description;
 import mops.gruppen2.domain.model.group.wrapper.Limit;
 import mops.gruppen2.domain.model.group.wrapper.Title;
 import mops.gruppen2.domain.service.GroupService;
-import mops.gruppen2.domain.service.ProjectionService;
+import mops.gruppen2.domain.service.helper.CsvHelper;
+import mops.gruppen2.domain.service.helper.ValidationHelper;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.keycloak.adapters.springsecurity.token.KeycloakAuthenticationToken;
-import org.springframework.cache.annotation.CacheEvict;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -36,8 +35,8 @@ import java.util.UUID;
 @RequestMapping("/gruppen2")
 public class GroupDetailsController {
 
+    private final GroupCache groupCache;
     private final GroupService groupService;
-    private final ProjectionService projectionService;
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @GetMapping("/details/{id}")
@@ -46,10 +45,13 @@ public class GroupDetailsController {
                                  @PathVariable("id") String groupId) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         // Parent Badge
-        Group parent = projectionService.projectParent(group.getParent());
+        Group parent = Group.EMPTY();
+        if (group.hasParent()) {
+            parent = groupCache.group(group.getParent());
+        }
 
         model.addAttribute("group", group);
         model.addAttribute("parent", parent);
@@ -64,12 +66,11 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/join")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsJoin(KeycloakAuthenticationToken token,
                                   @PathVariable("id") String groupId) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         if (ValidationHelper.checkIfMember(group, principal)) {
             return "redirect:/gruppen2/details/" + groupId;
@@ -82,12 +83,11 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/leave")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsLeave(KeycloakAuthenticationToken token,
                                    @PathVariable("id") String groupId) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         groupService.kickMember(group, principal, principal);
 
@@ -102,7 +102,7 @@ public class GroupDetailsController {
                                  @PathVariable("id") String groupId) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         // Invite Link
         String actualURL = request.getRequestURL().toString();
@@ -119,14 +119,15 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/edit/meta")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditMeta(KeycloakAuthenticationToken token,
                                       @PathVariable("id") String groupId,
                                       @Valid Title title,
                                       @Valid Description description) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
+
+        System.out.println(group);
 
         groupService.setTitle(group, principal, title);
         groupService.setDescription(group, principal, description);
@@ -136,12 +137,11 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/edit/userlimit")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditUserLimit(KeycloakAuthenticationToken token,
                                            @PathVariable("id") String groupId,
                                            @Valid Limit limit) {
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         groupService.setLimit(group, principal, limit);
 
@@ -150,13 +150,12 @@ public class GroupDetailsController {
 
     @RolesAllowed("ROLE_orga")
     @PostMapping("/details/{id}/edit/csv")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditCsv(KeycloakAuthenticationToken token,
                                      @PathVariable("id") String groupId,
                                      @RequestParam(value = "file", required = false) MultipartFile file) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         groupService.addUsersToGroup(group, principal, CsvHelper.readCsvFile(file));
 
@@ -165,13 +164,12 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/edit/role/{userid}")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditRole(KeycloakAuthenticationToken token,
                                       @PathVariable("id") String groupId,
                                       @PathVariable("userid") String target) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         ValidationHelper.throwIfNoAdmin(group, principal);
 
@@ -187,13 +185,12 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/edit/delete/{userid}")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditDelete(KeycloakAuthenticationToken token,
                                         @PathVariable("id") String groupId,
                                         @PathVariable("userid") String target) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupId));
+        Group group = groupCache.group(UUID.fromString(groupId));
 
         ValidationHelper.throwIfNoAdmin(group, principal);
 
@@ -207,12 +204,11 @@ public class GroupDetailsController {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @PostMapping("/details/{id}/edit/destroy")
-    @CacheEvict(value = "groups", allEntries = true)
     public String postDetailsEditDestroy(KeycloakAuthenticationToken token,
                                          @PathVariable("id") String groupid) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupById(UUID.fromString(groupid));
+        Group group = groupCache.group(UUID.fromString(groupid));
 
         groupService.deleteGroup(group, principal);
 
diff --git a/src/main/java/mops/gruppen2/web/GruppenfindungController.java b/src/main/java/mops/gruppen2/infrastructure/controller/GruppenfindungController.java
similarity index 75%
rename from src/main/java/mops/gruppen2/web/GruppenfindungController.java
rename to src/main/java/mops/gruppen2/infrastructure/controller/GruppenfindungController.java
index 465be52..15e1953 100644
--- a/src/main/java/mops/gruppen2/web/GruppenfindungController.java
+++ b/src/main/java/mops/gruppen2/infrastructure/controller/GruppenfindungController.java
@@ -1,10 +1,10 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure.controller;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.aspect.annotation.TraceMethodCall;
 import mops.gruppen2.domain.exception.PageNotFoundException;
-import mops.gruppen2.domain.service.ProjectionService;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.keycloak.adapters.springsecurity.token.KeycloakAuthenticationToken;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
@@ -20,22 +20,25 @@ import javax.servlet.http.HttpServletRequest;
 @Controller
 public class GruppenfindungController {
 
-    private final ProjectionService projectionService;
+    private final GroupCache groupCache;
 
     // For convenience
-    //@GetMapping("")
-    //public String redirect() {
-    //    return "redirect:/gruppen2";
-    //}
+    @GetMapping("")
+    public String redirect() {
+        return "redirect:/gruppen2";
+    }
+
+    @GetMapping("/login")
+    public String login() {
+        return "redirect:/gruppen2";
+    }
 
     @TraceMethodCall
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
     @GetMapping("/gruppen2")
     public String getIndexPage(KeycloakAuthenticationToken token,
                                Model model) {
-
-        String principal = token.getName();
-        model.addAttribute("groups", projectionService.projectUserGroups(principal));
+        model.addAttribute("groups", groupCache.userGroups(token.getName()));
 
         return "index";
     }
diff --git a/src/main/java/mops/gruppen2/web/SearchAndInviteController.java b/src/main/java/mops/gruppen2/infrastructure/controller/SearchAndInviteController.java
similarity index 90%
rename from src/main/java/mops/gruppen2/web/SearchAndInviteController.java
rename to src/main/java/mops/gruppen2/infrastructure/controller/SearchAndInviteController.java
index 10bc6f6..e9e9e16 100644
--- a/src/main/java/mops/gruppen2/web/SearchAndInviteController.java
+++ b/src/main/java/mops/gruppen2/infrastructure/controller/SearchAndInviteController.java
@@ -1,13 +1,13 @@
-package mops.gruppen2.web;
+package mops.gruppen2.infrastructure.controller;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import mops.gruppen2.aspect.annotation.TraceMethodCalls;
-import mops.gruppen2.domain.helper.ValidationHelper;
 import mops.gruppen2.domain.model.group.Group;
 import mops.gruppen2.domain.model.group.Type;
-import mops.gruppen2.domain.service.ProjectionService;
 import mops.gruppen2.domain.service.SearchService;
+import mops.gruppen2.domain.service.helper.ValidationHelper;
+import mops.gruppen2.infrastructure.GroupCache;
 import org.keycloak.adapters.springsecurity.token.KeycloakAuthenticationToken;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
@@ -29,7 +29,7 @@ import java.util.List;
 @RequestMapping("/gruppen2")
 public class SearchAndInviteController {
 
-    private final ProjectionService projectionService;
+    private final GroupCache groupCache;
     private final SearchService searchService;
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin"})
@@ -62,7 +62,7 @@ public class SearchAndInviteController {
                           @PathVariable("link") String link) {
 
         String principal = token.getName();
-        Group group = projectionService.projectGroupByLink(link);
+        Group group = groupCache.group(link);
 
         model.addAttribute("group", group);
 
diff --git a/src/main/java/mops/gruppen2/persistance/EventRepository.java b/src/main/java/mops/gruppen2/persistance/EventRepository.java
index d5b5164..0b187d7 100644
--- a/src/main/java/mops/gruppen2/persistance/EventRepository.java
+++ b/src/main/java/mops/gruppen2/persistance/EventRepository.java
@@ -11,43 +11,21 @@ import java.util.List;
 @Repository
 public interface EventRepository extends CrudRepository<EventDTO, Long> {
 
-    // ####################################### GROUP IDs #########################################
-
-    /*@Query("SELECT DISTINCT group_id FROM event"
-           + " WHERE user_id = :userId AND event_type = :type")
-    List<String> findGroupIdsByUserAndType(@Param("userId") String userId,
-                                           @Param("type") String type);*/
-
-    @Query("SELECT DISTINCT group_id FROM event"
-           + " WHERE event_id > :status")
-    List<String> findGroupIdsWhereEventIdGreaterThanStatus(@Param("status") long status);
 
     // ####################################### EVENT DTOs ########################################
 
-    @Query("SELECT * FROM event"
-           + " WHERE group_id IN (:groupIds) ")
-    List<EventDTO> findEventDTOsByGroup(@Param("groupIds") List<String> groupIds);
 
-    /*@Query("SELECT * FROM event"
-           + " WHERE group_id IN (:userIds) ")
-    List<EventDTO> findEventDTOsByUser(@Param("groupIds") String... userIds);*/
+    @Query("SELECT * FROM event WHERE event_id > :version AND event_id <= :max")
+    List<EventDTO> findNewEvents(@Param("version") long version,
+                                 @Param("max") long maxid);
 
-    @Query("SELECT * FROM event"
-           + " WHERE event_type IN (:types)")
-    List<EventDTO> findEventDTOsByType(@Param("types") List<String> types);
+    @Query("SELECT * FROM event")
+    List<EventDTO> findAllEvents();
 
-    @Query("SELECT * FROM event"
-           + " WHERE event_type IN (:types) AND group_id IN (:groupIds)")
-    List<EventDTO> findEventDTOsByGroupAndType(@Param("groupIds") List<String> groupIds,
-                                               @Param("types") List<String> types);
-
-    /*@Query("SELECT * FROM event"
-           + " WHERE event_type IN (:types) AND user_id = :userId")
-    List<EventDTO> findEventDTOsByUserAndType(@Param("userId") String userId,
-                                              @Param("types") String... types);*/
 
     // ################################ LATEST EVENT DTOs ########################################
 
+
     @Query("WITH ranked_events AS ("
            + "SELECT *, ROW_NUMBER() OVER (PARTITION BY group_id ORDER BY event_id DESC) AS rn"
            + " FROM event"
diff --git a/src/main/resources/application-dev.properties b/src/main/resources/application-dev.properties
index 13f17ef..824d245 100644
--- a/src/main/resources/application-dev.properties
+++ b/src/main/resources/application-dev.properties
@@ -12,11 +12,6 @@ spring.datasource.password                  =
 spring.jpa.database-platform                = org.hibernate.dialect.H2Dialect
 spring.h2.console.enabled                   = false
 
-# Security
-keycloak.auth-server-url                    = http://localhost:8082/auth
-hhu_keycloak.token-uri                      = http://localhost:8082/auth/realms/Gruppen/protocol/openid-connect/token
-
-
 # Misc
 server.error.include-stacktrace             = always
 management.endpoints.web.exposure.include   = info,health
diff --git a/src/main/resources/application-docker.properties b/src/main/resources/application-docker.properties
index 864d2dc..a9faa16 100644
--- a/src/main/resources/application-docker.properties
+++ b/src/main/resources/application-docker.properties
@@ -10,11 +10,6 @@ spring.datasource.url                       = jdbc:mysql://dbmysql:3306/gruppen
 spring.datasource.username                  = gruppen
 spring.datasource.password                  = password
 
-# Security
-keycloak.auth-server-url                    = http://localhost:8082/auth
-hhu_keycloak.token-uri                      = http://localhost:8082/auth/realms/Gruppen/protocol/openid-connect/token
-
-
 # Misc
 management.endpoints.web.exposure.include   = info,health
 server.error.include-stacktrace             = always
diff --git a/src/main/resources/application-heroku.properties b/src/main/resources/application-heroku.properties
index 3839b1b..2ddb9d8 100644
--- a/src/main/resources/application-heroku.properties
+++ b/src/main/resources/application-heroku.properties
@@ -10,10 +10,6 @@ spring.datasource.url                       = mysql://b4b665d39d0670:cc933ff7@eu
 spring.datasource.username                  = b4b665d39d0670
 spring.datasource.password                  = cc933ff7
 
-# Security
-keycloak.auth-server-url                    = https://gruppenkeycloak.herokuapp.com/auth
-hhu_keycloak.token-uri                      = https://gruppenkeycloak.herokuapp.com/auth/realms/master/protocol/openid-connect/token
-
 
 # Misc
 management.endpoints.web.exposure.include   = info,health
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
index 6866cba..45828c0 100644
--- a/src/main/resources/application.properties
+++ b/src/main/resources/application.properties
@@ -11,6 +11,8 @@ spring.profiles.active              = dev
 #keycloak.use-resource-role-mappings = true
 #keycloak.autodetect-bearer-only     = true
 #keycloak.confidential-port          = 443
+keycloak.auth-server-url            = https://gruppenkeycloak.herokuapp.com/auth
+hhu_keycloak.token-uri              = https://gruppenkeycloak.herokuapp.com/auth/realms/master/protocol/openid-connect/token
 keycloak.principal-attribute        = preferred_username
 keycloak.realm                      = master
 keycloak.resource                   = gruppen-app
diff --git a/src/test/java/mops/gruppen2/architecture/ControllerTest.java b/src/test/java/mops/gruppen2/architecture/ControllerTest.java
index 0920791..5867549 100644
--- a/src/test/java/mops/gruppen2/architecture/ControllerTest.java
+++ b/src/test/java/mops/gruppen2/architecture/ControllerTest.java
@@ -30,7 +30,7 @@ class ControllerTest {
     public static final ArchRule controllerClassesShouldBeInControllerPackage = classes()
             .that().areAnnotatedWith(Controller.class)
             .or().areAnnotatedWith(RestController.class)
-            .should().resideInAPackage("..web");
+            .should().resideInAPackage("..controller");
 
     @ArchTest
     public static final ArchRule classesInControllerPackageShouldHaveControllerInName = classes()
diff --git a/src/test/java/mops/gruppen2/architecture/ServiceTest.java b/src/test/java/mops/gruppen2/architecture/ServiceTest.java
index f71a9aa..84477a6 100644
--- a/src/test/java/mops/gruppen2/architecture/ServiceTest.java
+++ b/src/test/java/mops/gruppen2/architecture/ServiceTest.java
@@ -25,11 +25,11 @@ class ServiceTest {
     @ArchTest
     public static final ArchRule serviceClassesShouldBeInServicePackage = classes()
             .that().areAnnotatedWith(Service.class)
-            .should().resideInAPackage("..service..");
+            .should().resideInAPackage("..service");
 
     @ArchTest
     public static final ArchRule classesInServicePackageShouldHaveServiceInName = classes()
-            .that().resideInAPackage("..service..")
+            .that().resideInAPackage("..service")
             .should().haveSimpleNameEndingWith("Service");
 
     @ArchIgnore