diff --git a/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookService.java b/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookService.java
index 52323f689b..f8983dfd16 100644
--- a/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookService.java
+++ b/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookService.java
@@ -1,62 +1,18 @@
 package com.baeldung.spring.data.neo4j.service;
 
-
 import com.baeldung.spring.data.neo4j.model.Book;
-import com.baeldung.spring.data.neo4j.repostory.BookRepository;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.stereotype.Service;
 
-import java.util.*;
+import java.util.Map;
 
-@Service
-public class BookService {
+/**
+ * Created by SDN on 5/13/2016.
+ */
+public interface BookService {
+    Map<String, Object> graph(int limit);
 
-    @Autowired
-    private BookRepository bookRepository;
+    Book save(Book book);
 
-    private Map<String, Object> toD3Format(final Iterator<Map<String, Object>> result) {
-        List<Map<String,Object>> nodes = new ArrayList<Map<String,Object>>();
-        List<Map<String,Object>> rels= new ArrayList<Map<String,Object>>();
-        int i=0;
-        while (result.hasNext()) {
-            Map<String, Object> row = result.next();
-            nodes.add(map("title",row.get("book"),"label","book"));
-            int target=i;
-            i++;
-            for (Object name : (Collection) row.get("cast")) {
-                Map<String, Object> actor = map("title", name,"label","actor");
-                int source = nodes.indexOf(actor);
-                if (source == -1) {
-                    nodes.add(actor);
-                    source = i++;
-                }
-                rels.add(map("source",source,"target",target));
-            }
-        }
-        return map("nodes", nodes, "links", rels);
-    }
+    Book findBookById(Long id);
 
-    private Map<String, Object> map(final String key1, final Object value1, final String key2, final Object value2) {
-        Map<String, Object> result = new HashMap<String,Object>(2);
-        result.put(key1,value1);
-        result.put(key2,value2);
-        return result;
-    }
-
-    public Map<String, Object> graph(final int limit) {
-        Iterator<Map<String, Object>> result = bookRepository.graph(limit).iterator();
-        return toD3Format(result);
-    }
-
-    public Book save(final Book book){
-       return bookRepository.save(book);
-    }
-
-    public Book findBookById(final Long id){
-        return bookRepository.findOne(id);
-    }
-
-    public void deleteAllInGraph(){
-        bookRepository.deleteAll();
-    }
-}
\ No newline at end of file
+    void deleteAllInGraph();
+}
diff --git a/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookServiceImpl.java b/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookServiceImpl.java
new file mode 100644
index 0000000000..cd50f8b740
--- /dev/null
+++ b/spring-data-neo4j/src/main/java/com/baeldung/spring/data/neo4j/service/BookServiceImpl.java
@@ -0,0 +1,62 @@
+package com.baeldung.spring.data.neo4j.service;
+
+
+import com.baeldung.spring.data.neo4j.model.Book;
+import com.baeldung.spring.data.neo4j.repostory.BookRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.*;
+
+@Service
+public class BookServiceImpl implements BookService {
+
+    @Autowired
+    private BookRepository bookRepository;
+
+    private Map<String, Object> toD3Format(final Iterator<Map<String, Object>> result) {
+        List<Map<String,Object>> nodes = new ArrayList<Map<String,Object>>();
+        List<Map<String,Object>> rels= new ArrayList<Map<String,Object>>();
+        int i=0;
+        while (result.hasNext()) {
+            Map<String, Object> row = result.next();
+            nodes.add(map("title",row.get("book"),"label","book"));
+            int target=i;
+            i++;
+            for (Object name : (Collection) row.get("cast")) {
+                Map<String, Object> actor = map("title", name,"label","actor");
+                int source = nodes.indexOf(actor);
+                if (source == -1) {
+                    nodes.add(actor);
+                    source = i++;
+                }
+                rels.add(map("source",source,"target",target));
+            }
+        }
+        return map("nodes", nodes, "links", rels);
+    }
+
+    private Map<String, Object> map(final String key1, final Object value1, final String key2, final Object value2) {
+        Map<String, Object> result = new HashMap<String,Object>(2);
+        result.put(key1,value1);
+        result.put(key2,value2);
+        return result;
+    }
+
+    public Map<String, Object> graph(final int limit) {
+        Iterator<Map<String, Object>> result = bookRepository.graph(limit).iterator();
+        return toD3Format(result);
+    }
+
+    public Book save(final Book book){
+       return bookRepository.save(book);
+    }
+
+    public Book findBookById(final Long id){
+        return bookRepository.findOne(id);
+    }
+
+    public void deleteAllInGraph(){
+        bookRepository.deleteAll();
+    }
+}
\ No newline at end of file
diff --git a/spring-data-neo4j/src/test/java/com/baeldung/spring/data/neo4j/BookServiceTest.java b/spring-data-neo4j/src/test/java/com/baeldung/spring/data/neo4j/BookServiceTest.java
index 100465838e..9a791f87da 100644
--- a/spring-data-neo4j/src/test/java/com/baeldung/spring/data/neo4j/BookServiceTest.java
+++ b/spring-data-neo4j/src/test/java/com/baeldung/spring/data/neo4j/BookServiceTest.java
@@ -21,7 +21,7 @@ public class BookServiceTest {
     private static final Log LOGGER = LogFactory.getLog(BookServiceTest.class);
 
     @Autowired
-    private BookService bookService;
+    private BookService bookServiceImpl;
 
     @Test
     public void testSaveBook() {
@@ -33,8 +33,7 @@ public class BookServiceTest {
         book.setReleased(1876);
         book.setPerson(author1);
 
-        bookService.save(book);
-        final Book savedBook = bookService.findBookById(book.getId());
+        final Book savedBook = bookServiceImpl.save(book);
         assertEquals(book.getTitle(), savedBook.getTitle());
    }
 }