diff --git a/compose_viz/extends.py b/compose_viz/extends.py
new file mode 100644
index 0000000..0ec2903
--- /dev/null
+++ b/compose_viz/extends.py
@@ -0,0 +1,12 @@
+class Extends:
+    def __init__(self, from_file: str, service_name: str):
+        self._from_file = from_file
+        self._service_name = service_name
+
+    @property
+    def from_file(self):
+        return self._from_file
+
+    @property
+    def service_name(self):
+        return self._service_name
\ No newline at end of file
diff --git a/compose_viz/service.py b/compose_viz/service.py
index b61ccff..acf28aa 100644
--- a/compose_viz/service.py
+++ b/compose_viz/service.py
@@ -1,8 +1,10 @@
 from typing import List
 
+from compose_viz.extends import Extends
+
 
 class Service:
-    def __init__(self, name: str, image: str, ports: List[str] = [], networks: List[str] = [], volumes: List[str] = [], depends_on: List[str] = [], links: List[str] = [], extends: List[str] = []) -> None:
+    def __init__(self, name: str, image: str = None, ports: List[str] = [], networks: List[str] = [], volumes: List[str] = [], depends_on: List[str] = [], links: List[str] = [], extends: Extends = None) -> None:
         self._name = name
         self._image = image
         self._ports = ports
diff --git a/tests/test_extends.py b/tests/test_extends.py
new file mode 100644
index 0000000..3cf9c2f
--- /dev/null
+++ b/tests/test_extends.py
@@ -0,0 +1,6 @@
+import pytest
+from compose_viz.service import Service
+    
+def test_parse_file():
+    with pytest.raises(ValueError, match=r"Both image and extends are not defined in service 'frontend', aborting."):
+        Service(name='frontend')