Use formatters to control output granularity.

etc.skeleton/application.yml

@@ -90,14 +90,20 @@ messaging:
           protocol: '12'
           destination: '/topic/fcrepo'
 
-          # Message format: at the moment only `ActivityStreamsFormatter` is
-          # supported.
-          formatter: ActivityStreamsFormatter
+          # Message format: at the moment the following are supported:
+          # - `ASResourceFormatter`: Sends information about a resource being
+          #   created, updated or deleted, by who and when, with no further
+          #   information about what changed.
+          # - `ASDeltaFormatter`: Sends the same information as
+          #   `ASResourceFormatter` with the addition of the triples that were
+          #   added and the ones that were removed in the request. This may be
+          #   used to send rich provenance data to a preservation system.
+          formatter: ASResourceFormatter
 
           # Granularity level of messages. It can be one of:
-          # - `none`: No message is ever sent.
+          # - `none`: route is not used. No message is ever sent.
           # - `resource`: Messages are sent whenever a resource is created,
           #   updated or deleted. No details about what changed is included.
-          # - `provenance`: up to two messages are sent for each individual
+          # - `delta`: up to two messages are sent for each individual
           #   request: one for the added triples and one for the deleted triples.
-          level: resource
+          active: True

lakesuperior/messaging/formatters.py

@@ -2,10 +2,10 @@ import json
 import logging
 import uuid
 
-from activipy import vocab
+from abc import ABCMeta, abstractmethod
 
 
-class ActivityStreamsFormatter:
+class BaseASFormatter(metaclass=ABCMeta):
     '''
     Format message as ActivityStreams.
 
@@ -37,7 +37,7 @@ class ActivityStreamsFormatter:
         added.
         - `metadata`: provenance metadata as a rdflib.Graph object. This
         contains properties such as actor(s), action (add/remove), etc. This is
-        only present with messaging level set to `provenance`.
+        only meaningful for `ASDeltaFormatter`.
         '''
         self.uri = uri
         self.ev_type = ev_type
@@ -48,6 +48,45 @@ class ActivityStreamsFormatter:
         self.metadata = metadata
 
 
+    @abstractmethod
+    def __str__(self):
+        pass
+
+
+
+class ASResourceFormatter(BaseASFormatter):
+    '''
+    Sends information about a resource being created, updated or deleted, by
+    who and when, with no further information about what changed.
+    '''
+
+    def __str__(self):
+        '''
+        Output structured data as string.
+        '''
+        ret = {
+            '@context': 'https://www.w3.org/ns/activitystreams',
+            'id' : 'urn:uuid:{}'.format(uuid.uuid4()),
+            'type' : self.ev_type,
+            'name' : self.ev_names[self.ev_type],
+            'object' : {
+                'id' : self.uri,
+                'updated' : self.time,
+                'type' : self.type,
+            },
+            'actor' : self.metadata.setdefault('actor', None),
+        }
+
+        return json.dumps(ret)
+
+
+
+class ASDeltaFormatter(BaseASFormatter):
+    '''
+    Sends the same information as `ASResourceFormatter` with the addition of
+    the triples that were added and the ones that were removed in the request.
+    This may be used to send rich provenance data to a preservation system.
+    '''
     def __str__(self):
         '''
         Output structured data as string.
@@ -63,7 +102,7 @@ class ActivityStreamsFormatter:
                 'type' : self.type,
             },
             'actor' : self.metadata.setdefault('actor', None),
-            'data' : self.data or '',
+            'data' : self.data,
         }
 
         return json.dumps(ret)

lakesuperior/messaging/messenger.py

@@ -15,13 +15,13 @@ class Messenger:
 
     def __init__(self, config):
         for route in config['routes']:
-            handler_cls = getattr(handlers, route['handler'])
-            messenger.addHandler(handler_cls(route))
-            messenger.setLevel(logging.INFO)
-            #messenger.formatter = logging.Formatter('%(message)s')
-            formatter = getattr(formatters, route['formatter'])
+            if route['active']:
+                handler_cls = getattr(handlers, route['handler'])
+                messenger.addHandler(handler_cls(route))
+                messenger.setLevel(logging.INFO)
+                formatter = getattr(formatters, route['formatter'])
 
-            self._msg_routes.append((messenger, formatter))
+                self._msg_routes.append((messenger, formatter))
 
 
     def send(self, *args, **kwargs):