Addd hook capability

radicale/hook/__init__.py

@@ -0,0 +1,25 @@
+from radicale import utils
+
+INTERNAL_TYPES = ("none", "rabbitmq")
+
+
+def load(configuration):
+    """Load the storage module chosen in configuration."""
+    return utils.load_plugin(
+        INTERNAL_TYPES, "hook", "Hook", configuration)
+
+
+class BaseHook:
+    def __init__(self, configuration):
+        """Initialize BaseHook.
+
+        ``configuration`` see ``radicale.config`` module.
+        The ``configuration`` must not change during the lifetime of
+        this object, it is kept as an internal reference.
+
+        """
+        self.configuration = configuration
+
+    def notify(self, content):
+        """Upload a new or replace an existing item."""
+        raise NotImplementedError