diff --git a/src/cord_workflow_controller_client/workflow_run.py b/src/cord_workflow_controller_client/workflow_run.py
new file mode 100644
index 0000000..9d3cf99
--- /dev/null
+++ b/src/cord_workflow_controller_client/workflow_run.py
@@ -0,0 +1,366 @@
+#!/usr/bin/env python3
+
+# Copyright 2019-present Open Networking Foundation
+#
+# 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.
+
+"""
+Workflow Run
+
+This module implements Workflow Run interface
+"""
+
+import json
+import socketio
+
+from .countdown_latch import CountDownLatch
+from .utils import get_noop_logger, gen_id, gen_seq_id
+from .errors import ClientRPCError, ClientInputError, ClientResponseError
+
+WAIT_TIMEOUT = 10  # 10 seconds
+
+GREETING = 'cord.workflow.ctlsvc.greeting'
+WORKFLOW_RUN_UPDATE_STATUS = 'cord.workflow.ctlsvc.workflow.run.status'
+WORKFLOW_RUN_COUNT_EVENTS = 'cord.workflow.ctlsvc.workflow.run.count'
+WORKFLOW_RUN_FETCH_EVENT = 'cord.workflow.ctlsvc.workflow.run.fetch'
+WORKFLOW_RUN_NOTIFY_EVENT = 'cord.workflow.ctlsvc.workflow.run.notify'
+
+
+class WorkflowRun(object):
+    def __init__(self, workflow_id, workflow_run_id, logger=None, name=None):
+        self.sio = socketio.Client()
+        self.workflow_id = workflow_id
+        self.workflow_run_id = workflow_run_id
+
+        if logger:
+            self.logger = logger
+        else:
+            self.logger = get_noop_logger()
+
+        if name:
+            self.name = name
+        else:
+            self.name = 'workflow_run_%s' % gen_id()
+
+        self.req_id = gen_seq_id()
+
+        # set sio handlers
+        self.logger.debug('Setting event handlers to Socket.IO')
+        self.sio.on('connect', self.__on_sio_connect)
+        self.sio.on('disconnect', self.__on_sio_disconnect)
+        self.sio.on(GREETING, self.__on_greeting_message)
+        self.sio.on(WORKFLOW_RUN_UPDATE_STATUS, self.__on_update_status_message)
+        self.sio.on(WORKFLOW_RUN_COUNT_EVENTS, self.__on_count_events_message)
+        self.sio.on(WORKFLOW_RUN_FETCH_EVENT, self.__on_fetch_event_message)
+        self.sio.on(WORKFLOW_RUN_NOTIFY_EVENT, self.__on_notify_event_message)
+
+        self.handlers = {
+            'connect': self.__noop_connect_handler,
+            'disconnect': self.__noop_disconnect_handler,
+            'notify': self.__noop_notify_handler
+        }
+
+        # key is req_id
+        self.pending_requests = {}
+
+    def set_logger(self, logger):
+        self.logger = logger
+
+    def get_logger(self):
+        return self.logger
+
+    def __on_sio_connect(self):
+        self.logger.debug('connected to the server')
+        handler = self.handlers['connect']
+        if callable(handler):
+            handler()
+
+    def __noop_connect_handler(self):
+        self.logger.debug('no-op connect handler')
+
+    def __on_sio_disconnect(self):
+        self.logger.debug('disconnected from the server')
+        handler = self.handlers['disconnect']
+        if callable(handler):
+            handler()
+
+    def __noop_disconnect_handler(self):
+        self.logger.debug('no-op disconnect handler')
+
+    def __noop_notify_handler(self, workflow_id, workflow_run_id, topic):
+        self.logger.debug('no-op notify handler')
+
+    def __get_next_req_id(self):
+        req_id = self.req_id
+        self.req_id += 1
+        return req_id
+
+    def __on_greeting_message(self, data):
+        self.logger.debug('received a gretting message from the server')
+
+    def __on_notify_event_message(self, data):
+        """
+        Handler for a notify event
+        REQ = {
+            'topic': <topic>
+        }
+        """
+        self.logger.info('received a notify event message from the server')
+        topic = data['topic']
+
+        self.logger.info('a notify event message - topic (%s)' % topic)
+        if topic:
+            handler = self.handlers['notify']
+            if callable(handler):
+                self.logger.info('calling a notify event handler - %s' % handler)
+                handler(self.workflow_id, self.workflow_run_id, topic)
+
+    def __on_update_status_message(self, data):
+        self.__on_response(WORKFLOW_RUN_UPDATE_STATUS, data)
+
+    def __on_count_events_message(self, data):
+        self.__on_response(WORKFLOW_RUN_COUNT_EVENTS, data)
+
+    def __on_fetch_event_message(self, data):
+        self.__on_response(WORKFLOW_RUN_FETCH_EVENT, data)
+
+    def __check_pending_request(self, req_id):
+        """
+        Check a pending request
+        """
+        if req_id in self.pending_requests:
+            return True
+        return False
+
+    def __put_pending_request(self, api, params):
+        """
+        Put a pending request to a queue
+        """
+        req_id = self.__get_next_req_id()
+        latch = CountDownLatch()
+        params['req_id'] = req_id  # inject req_id
+        self.sio.emit(api, params)
+        self.pending_requests[req_id] = {
+            'req_id': req_id,
+            'latch': latch,
+            'api': api,
+            'params': params,
+            'result': None
+        }
+        return req_id
+
+    def __wait_response(self, req_id):
+        """
+        Wait for completion of a request
+        """
+        if req_id in self.pending_requests:
+            req = self.pending_requests[req_id]
+            # python v 3.2 or below does not return a result
+            # that tells whether it is timedout or not
+            return req['latch'].wait(WAIT_TIMEOUT)
+        else:
+            self.logger.error(
+                'cannot find a pending request (%s) from a queue' % req_id
+            )
+            raise ClientRPCError(
+                req_id,
+                'cannot find a pending request (%s) from a queue' % req_id
+            )
+
+    def __complete_request(self, req_id, result):
+        """
+        Compelete a pending request
+        """
+        if req_id in self.pending_requests:
+            req = self.pending_requests[req_id]
+            req['latch'].count_down()
+            req['result'] = result
+            return
+
+        self.logger.error(
+            'cannot find a pending request (%s) from a queue' % req_id
+        )
+        raise ClientRPCError(
+            req_id,
+            'cannot find a pending request (%s) from a queue' % req_id
+        )
+
+    def __pop_pending_request(self, req_name):
+        """
+        Pop a pending request from a queue
+        """
+        return self.pending_requests.pop(req_name, None)
+
+    def connect(self, url):
+        """
+        Connect to the given url
+        """
+        query_string = 'id=%s&type=workflow_run&name=%s&workflow_id=%s&workflow_run_id=%s' % \
+            (self.name, self.name, self.workflow_id, self.workflow_run_id)
+        connect_url = '%s?%s' % (url, query_string)
+
+        if not (connect_url.startswith('http://') or connect_url.startswith('https://')):
+            connect_url = 'http://%s' % connect_url
+
+        self.logger.debug('Connecting to a Socket.IO server (%s)' % connect_url)
+        self.sio.connect(url=connect_url, transports=['websocket'])
+
+    def disconnect(self):
+        """
+        Disconnect from the server
+        """
+        self.sio.disconnect()
+
+    def wait(self):
+        self.sio.wait()
+
+    def sleep(self, sec):
+        self.sio.sleep(sec)
+
+    def get_handlers(self):
+        return self.handlers
+
+    def set_handlers(self, new_handlers):
+        for k in self.handlers:
+            if k in new_handlers:
+                self.handlers[k] = new_handlers[k]
+
+    def __request(self, api, params={}):
+        if api and params:
+            req_id = self.__put_pending_request(api, params)
+            self.logger.debug('waiting for a response for req_id (%s)' % req_id)
+            self.__wait_response(req_id)  # wait for completion
+            req = self.__pop_pending_request(req_id)
+            if req:
+                if req['latch'].get_count() > 0:
+                    # timed out
+                    self.logger.error('request (%s) timed out' % req_id)
+                    raise ClientRPCError(
+                        req_id,
+                        'request (%s) timed out' % req_id
+                    )
+                else:
+                    return req['result']
+            else:
+                self.logger.error('cannot find a pending request (%s) from a queue' % req_id)
+                raise ClientRPCError(
+                    req_id,
+                    'cannot find a pending request (%s) from a queue' % req_id
+                )
+        else:
+            self.logger.error(
+                'invalid arguments api (%s), params (%s)' %
+                (api, json.dumps(params))
+            )
+            raise ClientInputError(
+                'invalid arguments api (%s), params (%s)' %
+                (api, json.dumps(params))
+            )
+
+    def __on_response(self, api, result):
+        if result and 'req_id' in result:
+            self.logger.debug('completing a request (%s)' % result['req_id'])
+            self.__complete_request(result['req_id'], result)
+        else:
+            self.logger.error(
+                'invalid arguments api (%s), result (%s)' %
+                (api, json.dumps(result))
+            )
+            raise ClientInputError(
+                'invalid arguments api (%s), result (%s)' %
+                (api, json.dumps(result))
+            )
+
+    def update_status(self, task_id, status):
+        """
+        Update status of a workflow run.
+        """
+        if task_id and status:
+            result = self.__request(WORKFLOW_RUN_UPDATE_STATUS, {
+                'workflow_id': self.workflow_id,
+                'workflow_run_id': self.workflow_run_id,
+                'task_id': task_id,
+                'status': status
+            })
+            if result['error']:
+                self.logger.error(
+                    'request (%s) failed with an error - %s' %
+                    (result['req_id'], result['message'])
+                )
+                raise ClientResponseError(
+                    'request (%s) failed with an error - %s' %
+                    (result['req_id'], result['message'])
+                )
+            else:
+                return result['result']
+        else:
+            self.logger.error(
+                'invalid arguments task_id (%s) and status (%s)' %
+                (task_id, status)
+            )
+            raise ClientInputError(
+                'invalid arguments task_id (%s) and status (%s)' %
+                (task_id, status)
+            )
+
+    def count_events(self):
+        """
+        Count events.
+        """
+        result = self.__request(WORKFLOW_RUN_COUNT_EVENTS, {
+            'workflow_id': self.workflow_id,
+            'workflow_run_id': self.workflow_run_id
+        })
+        if result['error']:
+            self.logger.error(
+                'request (%s) failed with an error - %s' %
+                (result['req_id'], result['message'])
+            )
+            raise ClientResponseError(
+                'request (%s) failed with an error - %s' %
+                (result['req_id'], result['message'])
+            )
+        else:
+            return result['result']
+
+    def fetch_event(self, task_id, topic):
+        """
+        Fetch an event.
+        """
+        if task_id and topic:
+            result = self.__request(WORKFLOW_RUN_FETCH_EVENT, {
+                'workflow_id': self.workflow_id,
+                'workflow_run_id': self.workflow_run_id,
+                'task_id': task_id,
+                'topic': topic
+            })
+            if result['error']:
+                self.logger.error(
+                    'request (%s) failed with an error - %s' %
+                    (result['req_id'], result['message'])
+                )
+                raise ClientResponseError(
+                    'request (%s) failed with an error - %s' %
+                    (result['req_id'], result['message'])
+                )
+            else:
+                return result['result']
+        else:
+            self.logger.error(
+                'invalid arguments task_id (%s), topic (%s)' %
+                (task_id, topic)
+            )
+            raise ClientInputError(
+                'invalid arguments task_id (%s), topic (%s)' %
+                (task_id, topic)
+            )