diff --git a/adapters/common/event_bus.py b/adapters/common/event_bus.py
new file mode 100644
index 0000000..e717c16
--- /dev/null
+++ b/adapters/common/event_bus.py
@@ -0,0 +1,194 @@
+#
+# Copyright 2017 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+A simple internal pub/sub event bus with topics and filter-based registration.
+"""
+import re
+
+import structlog
+
+
+log = structlog.get_logger()
+
+
+class _Subscription(object):
+
+    __slots__ = ('bus', 'predicate', 'callback', 'topic')
+    def __init__(self, bus, predicate, callback, topic=None):
+        self.bus = bus
+        self.predicate = predicate
+        self.callback = callback
+        self.topic = topic
+
+
+class EventBus(object):
+
+    def __init__(self):
+        self.subscriptions = {}  # topic -> list of _Subscription objects
+                                 # topic None holds regexp based topic subs.
+        self.subs_topic_map = {} # to aid fast lookup when unsubscribing
+
+    def list_subscribers(self, topic=None):
+        if topic is None:
+            return sum(self.subscriptions.itervalues(), [])
+        else:
+            if topic in self.subscriptions:
+                return self.subscriptions[topic]
+            else:
+                return []
+
+    @staticmethod
+    def _get_topic_key(topic):
+        if isinstance(topic, str):
+            return topic
+        elif hasattr(topic, 'match'):
+            return None
+        else:
+            raise AttributeError('topic not a string nor a compiled regex')
+
+    def subscribe(self, topic, callback, predicate=None):
+        """
+        Subscribe to given topic with predicate and register the callback
+        :param topic: String topic (explicit) or regexp based topic filter.
+        :param callback: Callback method with signature def func(topic, msg)
+        :param predicate: Optional method/function signature def predicate(msg)
+        :return: Subscription object which can be used to unsubscribe
+        """
+        subscription = _Subscription(self, predicate, callback, topic)
+        topic_key = self._get_topic_key(topic)
+        self.subscriptions.setdefault(topic_key, []).append(subscription)
+        self.subs_topic_map[subscription] = topic_key
+        return subscription
+
+    def unsubscribe(self, subscription):
+        """
+        Remove given subscription
+        :param subscription: subscription object as was returned by subscribe
+        :return: None
+        """
+        topic_key = self.subs_topic_map[subscription]
+        self.subscriptions[topic_key].remove(subscription)
+
+    def publish(self, topic, msg):
+        """
+        Publish given message to all subscribers registered with topic taking
+        the predicate functions into account.
+        :param topic: String topic
+        :param msg: Arbitrary python data as message
+        :return: None
+        """
+        from copy import copy
+
+        def passes(msg, predicate):
+            try:
+                return predicate(msg)
+            except Exception, e:
+                return False  # failed predicate function treated as no match
+
+        # lookup subscribers with explicit topic subscriptions
+        subscribers = self.subscriptions.get(topic, [])
+
+        # add matching regexp topic subscribers
+        subscribers.extend(s for s in self.subscriptions.get(None, [])
+                           if s.topic.match(topic))
+
+        # iterate over a shallow-copy of subscribers
+        for candidate in copy(subscribers):
+            predicate = candidate.predicate
+            if predicate is None or passes(msg, predicate):
+                try:
+                    candidate.callback(topic, msg)
+                except Exception, e:
+                    log.exception('callback-failed', e=repr(e), topic=topic)
+
+
+
+default_bus = EventBus()
+
+
+class EventBusClient(object):
+    """
+    Primary interface to the EventBus. Usage:
+
+    Publish:
+    >>> events = EventBusClient()
+    >>> msg = dict(a=1, b='foo')
+    >>> events.publish('a.topic', msg)
+
+    Subscribe to get all messages on specific topic:
+    >>> def got_event(topic, msg):
+    >>>     print topic, ':', msg
+    >>> events = EventBusClient()
+    >>> events.subscribe('a.topic', got_event)
+
+    Subscribe to get messages matching predicate on specific topic:
+    >>> def got_event(topic, msg):
+    >>>     print topic, ':', msg
+    >>> events = EventBusClient()
+    >>> events.subscribe('a.topic', got_event, lambda msg: msg.len() < 100)
+
+    Use a DeferredQueue to buffer incoming messages
+    >>> queue = DeferredQueue()
+    >>> events = EventBusClient()
+    >>> events.subscribe('a.topic', lambda _, msg: queue.put(msg))
+
+    """
+    def __init__(self, bus=None):
+        """
+        Obtain a client interface for the pub/sub event bus.
+        :param bus: An optional specific event bus. Inteded for mainly test
+        use. If not provided, the process default bus will be used, which is
+        the preferred use (a process shall not need more than one bus).
+        """
+        self.bus = bus or default_bus
+
+    def publish(self, topic, msg):
+        """
+        Publish given msg to given topic.
+        :param topic: String topic
+        :param msg: Arbitrary python data as message
+        :return: None
+        """
+        self.bus.publish(topic, msg)
+
+    def subscribe(self, topic, callback, predicate=None):
+        """
+        Subscribe to given topic with predicate and register the callback
+        :param topic: String topic (explicit) or regexp based topic filter.
+        :param callback: Callback method with signature def func(topic, msg)
+        :param predicate: Optional method/function with signature
+        def predicate(msg)
+        :return: Subscription object which can be used to unsubscribe
+        """
+        return self.bus.subscribe(topic, callback, predicate)
+
+    def unsubscribe(self, subscription):
+        """
+        Remove given subscription
+        :param subscription: subscription object as was returned by subscribe
+        :return: None
+        """
+        return self.bus.unsubscribe(subscription)
+
+    def list_subscribers(self, topic=None):
+        """
+        Return list of subscribers. If topci is provided, it is filtered for
+        those subscribing to the topic.
+        :param topic: Optional topic
+        :return: List of subscriptions
+        """
+        return self.bus.list_subscribers(topic)