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 56e936d..883f781 100644
--- a/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java
+++ b/src/main/java/com/example/cosmos_serversb/resources/GroupsRest.java
@@ -6,6 +6,8 @@
 
 import javax.ws.rs.*;
 
+import com.example.cosmos_serversb.models.*;
+
 @Component
 
 public class GroupsRest {
@@ -13,7 +15,7 @@
     @GET
     public String getGroupsListByUid(@QueryParam("uId") String uId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().getGroupsListByUid(uId));
         return json;
     }
 
@@ -21,15 +23,15 @@
     @POST
     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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().createGroup(name, uId));
         return json;
     }
 
     @Path("/{gId}")
     @GET
-    public String getGroupInfoByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
+    public String getGroupByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().getGroupByGid(gId));
         return json;
     }
 
@@ -37,7 +39,7 @@
     @DELETE
     public String deleteGroup(@PathParam("gId") String gId, @FormParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteGroup(gId));
         return json;
     }
 
@@ -45,7 +47,7 @@
     @GET
     public String getGroupMembersListByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().getMembersListByGid(gId));
         return json;
     }
 
@@ -53,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().addMember(gId, uId));
         return json;
     }
 
@@ -61,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteMember(gId, uId));
         return json;
     }
 
@@ -69,7 +71,7 @@
     @GET
     public String getRequestsListByGid(@PathParam("gId") String gId, @QueryParam("token") String token) throws JsonProcessingException{
         ObjectMapper mapper = new ObjectMapper();
-        String json = mapper.writeValueAsString(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().getRequestsListByGid(gId));
         return json;
     }
 
@@ -77,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().addRequests(gId, uId, product, deadline, location));
         return json;
     }
 
@@ -85,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().getRequestDetailByGidAndRid(gId, rId));
         return json;
     }
 
@@ -93,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().updateRequest(gId, rId, uId, product, deadline, location, done));
         return json;
     }
 
@@ -101,7 +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(null);
+        String json = mapper.writeValueAsString(Groups.getInstance().deleteRequest(gId, rId));
         return json;
     }
 }