diff --git a/service/__init__.py b/service/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/service/base.py b/service/base.py
new file mode 100644
index 0000000..651607e
--- /dev/null
+++ b/service/base.py
@@ -0,0 +1,7 @@
+from abc import ABC, abstractmethod
+from uuid import UUID
+
+
+class Service(ABC):
+    def __init__(self, model: UUID):
+        self.model = model
diff --git a/service/bottom_0.py b/service/bottom_0.py
new file mode 100644
index 0000000..4a6be94
--- /dev/null
+++ b/service/bottom_0.py
@@ -0,0 +1,81 @@
+from service.base import Service, UUID
+from state.base import State
+from typing import Any, List
+
+
+class Bottom0(Service):
+    def __init__(self, model: UUID, state: State):
+        super().__init__(model)
+        self.state = state
+
+    def create_node(self, value=None) -> UUID:
+        if value is None:
+            return self.state.create_node()
+        else:
+            return self.state.create_nodevalue(value)
+
+    def create_edge(self, source: UUID, target: UUID, label=None):
+        pass
+
+    def read_model_root(self) -> UUID:
+        return self.model
+
+    def read_value(self, node: UUID) -> Any:
+        return self.state.read_value(node)
+
+    def read_edge_source(self, edge: UUID) -> UUID:
+        result = self.state.read_edge(edge)
+        return result[0] if result is not None else result
+
+    def read_edge_target(self, edge: UUID) -> UUID:
+        result = self.state.read_edge(edge)
+        return result[1] if result is not None else result
+
+    def read_incoming_edges(self, target: UUID, label=None) -> List[UUID]:
+        def read_label(_edge: UUID):
+            try:
+                label_edge, = self.state.read_outgoing(_edge)
+                _, tgt = self.state.read_edge(label_edge)
+                _label = self.state.read_value(tgt)
+                return _label
+            except (TypeError, ValueError):
+                return None
+
+        edges = self.state.read_incoming(target)
+        if edges is None:
+            return []
+        if label is not None:
+            edges = [e for e in edges if read_label(e) == label]
+        return edges
+
+    def read_outgoing_edges(self, source: UUID, label=None) -> List[UUID]:
+        def read_label(_edge: UUID):
+            try:
+                label_edge, = self.state.read_outgoing(_edge)
+                _, tgt = self.state.read_edge(label_edge)
+                _label = self.state.read_value(tgt)
+                return _label
+            except (TypeError, ValueError):
+                return None
+
+        edges = self.state.read_outgoing(source)
+        if edges is None:
+            return []
+        if label is not None:
+            edges = [e for e in edges if read_label(e) == label]
+        return edges
+
+    def read_keys(self, element: UUID) -> List[str]:
+        key_nodes = self.state.read_dict_keys(element)
+        unique_keys = {self.state.read_value(node) for node in key_nodes}
+        return list(unique_keys)
+
+    def delete_element(self, element: UUID):
+        src, tgt = self.state.read_edge(element)
+        if src is None and tgt is None:
+            # node
+            self.state.delete_node(element)
+        else:
+            # edge
+            self.state.delete_edge(element)
+