diff --git a/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java b/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java
index 4e99566..883f781 100644
--- a/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java
+++ b/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java
@@ -15,15 +15,15 @@
     @GET
     public String getGroupsListByUid(@QueryParam("uId") String uId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.getGroupsListByUid(uId));
+        String json = mapper.writeValueAsString(Groups.getInstance().getGroupsListByUid(uId));
         return json;
     }
 
     @Path("/groups")
     @POST
-    public String createGroup(@FormParam("name") String name, @FormParam("uId") String uId) throws JsonProcessingException{
+    public String createGroup(@FormParam("name") String name, @FormParam("uId") String uId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.createGroup(name, uId));
+        String json = mapper.writeValueAsString(Groups.getInstance().createGroup(name, uId));
         return json;
     }
 
@@ -31,7 +31,7 @@
     @GET
     public String getGroupByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.getGroupByGid(gId));
+        String json = mapper.writeValueAsString(Groups.getInstance().getGroupByGid(gId));
         return json;
     }
 
@@ -39,7 +39,7 @@
     @DELETE
     public String deleteGroup(@PathParam("gId") String gId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.deleteGroup(gId));
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteGroup(gId));
         return json;
     }
 
@@ -47,7 +47,7 @@
     @GET
     public String getGroupMembersListByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.getMembersListByGid(gId));
+        String json = mapper.writeValueAsString(Groups.getInstance().getMembersListByGid(gId));
         return json;
     }
 
@@ -55,7 +55,7 @@
     @POST
     public String addMember(@PathParam("gId") String gId, @FormParam("uId") String uId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.addMember(gId, uId));
+        String json = mapper.writeValueAsString(Groups.getInstance().addMember(gId, uId));
         return json;
     }
 
@@ -63,7 +63,7 @@
     @DELETE
     public String deleteMember(@PathParam("gId") String gId, @FormParam("uId") String uId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.deleteMember(gId, uId));
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteMember(gId, uId));
         return json;
     }
 
@@ -71,7 +71,7 @@
     @GET
     public String getRequestsListByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.getRequestsListByGid(gId));
+        String json = mapper.writeValueAsString(Groups.getInstance().getRequestsListByGid(gId));
         return json;
     }
 
@@ -79,7 +79,7 @@
     @POST
     public String addRequests(@PathParam("gId") String gId, @FormParam("uId") String uId, @FormParam("product") String product, @FormParam("deadline") String deadline, @FormParam("location") int location, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.addRequests(gId, uId, product, deadline, location));
+        String json = mapper.writeValueAsString(Groups.getInstance().addRequests(gId, uId, product, deadline, location));
         return json;
     }
 
@@ -87,7 +87,7 @@
     @GET
     public String getRequestsDetailByGidAndRid(@PathParam("gId") String gId, @PathParam("rId") String rId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.getRequestDetailByGidAndRid(gId, rId));
+        String json = mapper.writeValueAsString(Groups.getInstance().getRequestDetailByGidAndRid(gId, rId));
         return json;
     }
 
@@ -95,7 +95,7 @@
     @PUT
     public String updateRequest(@PathParam("gId") String gId, @PathParam("rId") String rId, @FormParam("uId") String uId, @FormParam("product") String product, @FormParam("deadline") String deadline, @FormParam("location") int location, @FormParam("done") boolean done, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.updateRequest(gId, rId, uId, product, deadline, location, done));
+        String json = mapper.writeValueAsString(Groups.getInstance().updateRequest(gId, rId, uId, product, deadline, location, done));
         return json;
     }
 
@@ -103,7 +103,7 @@
     @DELETE
     public String deleteRequest(@PathParam("gId") String gId, @PathParam("rId") String rId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(Groups.deleteRequest(gId, rId));
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteRequest(gId, rId));
         return json;
     }
 }