diff --git a/voter-registry/src/main/java/meerkat/RegistryInstance.java b/voter-registry/src/main/java/meerkat/RegistryInstance.java
index f7da07f..7fa4f40 100644
--- a/voter-registry/src/main/java/meerkat/RegistryInstance.java
+++ b/voter-registry/src/main/java/meerkat/RegistryInstance.java
@@ -4,14 +4,14 @@ package meerkat;
  * Created by Vladimir Eliezer Tokarev on 1/22/2016.
  * provides voters management options
  */
-public abstract class RegistryInstance {
+public interface RegistryInstance {
 
     /**
      * Adds new voter to the bulletin-board
      *
-     * @param voterID id of the new user
+     * @param voterID      id of the new user
      * @param personalData for example residence location
-     * @param callBack when the adding voter done callBack.HandleVoterAdded will be called
+     * @param callBack     when the adding voter done callBack.HandleVoterAdded will be called
      * @return void
      */
     abstract void AddVoter(String voterID, String personalData, RegistryCallBack callBack);
@@ -19,8 +19,8 @@ public abstract class RegistryInstance {
     /**
      * Adding given voter to given group
      *
-     * @param voterID the voter id
-     * @param groupID the group id to which we want add the voter
+     * @param voterID  the voter id
+     * @param groupID  the group id to which we want add the voter
      * @param callBack when the adding voter done callBack.HandleVoterAddedToGroup will be called
      * @return true if the adding action succeeded else return false
      */
@@ -29,8 +29,8 @@ public abstract class RegistryInstance {
     /**
      * Removes given voter from given group
      *
-     * @param voterID the voter id
-     * @param groupID the group from which we want to remove the user
+     * @param voterID  the voter id
+     * @param groupID  the group from which we want to remove the user
      * @param callBack when the adding voter done callBack.HandleVoterRemovedFromGroup will be called
      * @return true if the removing action succeeded else return false
      */
@@ -39,7 +39,7 @@ public abstract class RegistryInstance {
     /**
      * Sets that the voter have voted
      *
-     * @param id id tag string
+     * @param id       id tag string
      * @param callBack when the adding voter done callBack.HandleSetVoted will be called
      * @return true if the set voted succeed else false
      */
@@ -48,7 +48,7 @@ public abstract class RegistryInstance {
     /**
      * Requests all the groups that the given id voter is in
      *
-     * @param id id tag string
+     * @param id       id tag string
      * @param callBack when the adding voter done callBack.HandleVoterGroups will be called
      * @return list of groups ids (or names), if the method fails its empty
      */
@@ -57,9 +57,10 @@ public abstract class RegistryInstance {
     /**
      * Retrieves list of strings that represents voter
      *
-     * @param id id tag string
+     * @param id       id tag string
      * @param callBack when the adding voter done callBack.HandleVoterInfo will be called
      * @return list of strings (empty list if the lookup failed)
      */
     abstract void GetPersonIDDetails(String id, RegistryCallBack callBack);
 }
+