diff --git a/substrafl/nodes/protocol.py b/substrafl/nodes/protocol.py
index 077efa03..8ffc5f0f 100644
--- a/substrafl/nodes/protocol.py
+++ b/substrafl/nodes/protocol.py
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from typing import Any
 from typing import List
 from typing import Protocol
@@ -16,15 +17,19 @@ class TrainDataNodeProtocol(Protocol):
     data_manager_key: str
     data_sample_keys: List[str]
 
+    @abstractmethod
     def init_states(self, *args, **kwargs) -> LocalStateRef:
         pass
 
+    @abstractmethod
     def update_states(self, operation: RemoteDataOperation, *args, **kwargs) -> (LocalStateRef, Any):
         pass
 
+    @abstractmethod
     def register_operations(self, client: substra.Client, *args, **kwargs) -> Any:
         pass
 
+    @abstractmethod
     def summary(self) -> dict:
         pass
 
@@ -35,12 +40,15 @@ class TestDataNodeProtocol(Protocol):
     data_manager_key: str
     data_sample_keys: List[str]
 
+    @abstractmethod
     def update_states(self, operation: RemoteDataOperation, *args, **kwargs) -> None:
         pass
 
+    @abstractmethod
     def register_operations(self, client: substra.Client, *args, **kwargs) -> Any:
         pass
 
+    @abstractmethod
     def summary(self) -> dict:
         pass
 
@@ -49,11 +57,14 @@ def summary(self) -> dict:
 class AggregationNodeProtocol(Protocol):
     organization_id: str
 
+    @abstractmethod
     def update_states(self, operation: RemoteOperation, *args, **kwargs) -> Any:
         pass
 
+    @abstractmethod
     def register_operations(self, client: substra.Client, *args, **kwargs) -> Any:
         pass
 
+    @abstractmethod
     def summary(self) -> dict:
         pass