diff --git a/web/app/corpora/events.py b/web/app/corpora/events.py
index 7e085814..22804fbe 100644
--- a/web/app/corpora/events.py
+++ b/web/app/corpora/events.py
@@ -4,12 +4,13 @@ from flask_login import current_user
 from socket import gaierror
 from .. import db, socketio
 from ..decorators import socketio_login_required
-from ..events import connected_sessions
+from ..events import socketio_sessions
 from ..models import Corpus, User
 import cqi
 import math
 import os
 import shutil
+import logging
 
 
 '''
@@ -282,7 +283,7 @@ def corpus_analysis_session_handler(app, corpus_id, user_id, session_id):
         response = {'code': 200, 'desc': None, 'msg': 'OK', 'payload': payload}
         socketio.emit('corpus_analysis_init', response, room=session_id)
         ''' Observe analysis session '''
-        while session_id in connected_sessions:
+        while session_id in socketio_sessions:
             socketio.sleep(3)
         ''' Teardown analysis session '''
         if client.status == 'running':
diff --git a/web/app/corpora/tasks.py b/web/app/corpora/tasks.py
index f65a00de..3ad43740 100644
--- a/web/app/corpora/tasks.py
+++ b/web/app/corpora/tasks.py
@@ -1,4 +1,4 @@
-from .. import db
+from .. import db, socketio
 from ..decorators import background
 from ..models import Corpus, CorpusFile, QueryResult
 
@@ -12,6 +12,11 @@ def build_corpus(corpus_id, *args, **kwargs):
             raise Exception('Corpus {} not found'.format(corpus_id))
         corpus.build()
         db.session.commit()
+        event = 'user_{}_patch'.format(corpus.user_id)
+        jsonpatch = [{'op': 'replace', 'path': '/corpora/{}/last_edited_date'.format(corpus.id), 'value': corpus.last_edited_date.timestamp()},  # noqa
+                     {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}]  # noqa
+        room = 'user_{}'.format(corpus.user_id)
+        socketio.emit(event, jsonpatch, room=room)
 
 
 @background
@@ -20,8 +25,12 @@ def delete_corpus(corpus_id, *args, **kwargs):
         corpus = Corpus.query.get(corpus_id)
         if corpus is None:
             raise Exception('Corpus {} not found'.format(corpus_id))
+        event = 'user_{}_patch'.format(corpus.user_id)
+        jsonpatch = [{'op': 'remove', 'path': '/corpora/{}'.format(corpus.id)}]
+        room = 'user_{}'.format(corpus.user_id)
         corpus.delete()
         db.session.commit()
+        socketio.emit(event, jsonpatch, room=room)
 
 
 @background
@@ -30,8 +39,13 @@ def delete_corpus_file(corpus_file_id, *args, **kwargs):
         corpus_file = CorpusFile.query.get(corpus_file_id)
         if corpus_file is None:
             raise Exception('Corpus file {} not found'.format(corpus_file_id))
+        event = 'user_{}_patch'.format(corpus_file.corpus.user_id)
+        jsonpatch = [{'op': 'remove', 'path': '/corpora/{}/files/{}'.format(corpus_file.corpus_id, corpus_file.id)},  # noqa
+                     {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus_file.corpus_id), 'value': corpus_file.corpus.status}]  # noqa
+        room = 'user_{}'.format(corpus_file.corpus.user_id)
         corpus_file.delete()
         db.session.commit()
+        socketio.emit(event, jsonpatch, room=room)
 
 
 @background
@@ -40,5 +54,9 @@ def delete_query_result(query_result_id, *args, **kwargs):
         query_result = QueryResult.query.get(query_result_id)
         if query_result is None:
             raise Exception('QueryResult {} not found'.format(query_result_id))
+        event = 'user_{}_patch'.format(query_result.user_id)
+        jsonpatch = [{'op': 'remove', 'path': '/query_results/{}'.format(query_result.id)}]  # noqa
+        room = 'user_{}'.format(query_result.user_id)
         query_result.delete()
         db.session.commit()
+        socketio.emit(event, jsonpatch, room=room)
diff --git a/web/app/corpora/views.py b/web/app/corpora/views.py
index d4382211..cef864c9 100644
--- a/web/app/corpora/views.py
+++ b/web/app/corpora/views.py
@@ -8,7 +8,7 @@ from .forms import (AddCorpusFileForm, AddCorpusForm, AddQueryResultForm,
                     DisplayOptionsForm, InspectDisplayOptionsForm,
                     ImportCorpusForm)
 from jsonschema import validate
-from .. import db
+from .. import db, socketio
 from ..models import Corpus, CorpusFile, QueryResult
 import json
 import logging
@@ -29,16 +29,22 @@ def add_corpus():
                         description=form.description.data,
                         title=form.title.data)
         db.session.add(corpus)
-        db.session.commit()
+        db.session.flush()
+        db.session.refresh(corpus)
         try:
             os.makedirs(corpus.path)
         except OSError:
             logging.error('Make dir {} led to an OSError!'.format(corpus.path))
-            db.session.delete(corpus)
-            db.session.commit()
+            db.session.rollback()
             abort(500)
-        flash('Corpus "{}" added!'.format(corpus.title), 'corpus')
-        return redirect(url_for('.corpus', corpus_id=corpus.id))
+        else:
+            db.session.commit()
+            flash('Corpus "{}" added!'.format(corpus.title), 'corpus')
+            event = 'user_{}_patch'.format(corpus.user_id)
+            jsonpatch = [{'op': 'add', 'path': '/corpora/{}'.format(corpus.id), 'value': corpus.to_dict()}]  # noqa
+            room = 'user_{}'.format(corpus.user_id)
+            socketio.emit(event, jsonpatch, room=room)
+            return redirect(url_for('.corpus', corpus_id=corpus.id))
     return render_template('corpora/add_corpus.html.j2', form=form,
                            title='Add corpus')
 
@@ -54,13 +60,13 @@ def import_corpus():
                         description=form.description.data,
                         title=form.title.data)
         db.session.add(corpus)
-        db.session.commit()
+        db.session.flush()
+        db.session.refresh(corpus)
         try:
             os.makedirs(corpus.path)
         except OSError:
             logging.error('Make dir {} led to an OSError!'.format(corpus.path))
-            db.session.delete(corpus)
-            db.session.commit()
+            db.session.rollback()
             flash('Internal Server Error', 'error')
             return make_response(
                 {'redirect_url': url_for('.import_corpus')}, 500)
@@ -100,6 +106,10 @@ def import_corpus():
             db.session.commit()
             os.remove(archive_file)
             flash('Corpus "{}" imported!'.format(corpus.title), 'corpus')
+            event = 'user_{}_patch'.format(corpus.user_id)
+            jsonpatch = [{'op': 'add', 'path': '/corpora/{}'.format(corpus.id), 'value': corpus.to_dict()}]  # noqa
+            room = 'user_{}'.format(corpus.user_id)
+            socketio.emit(event, jsonpatch, room=room)
             return make_response(
                 {'redirect_url': url_for('.corpus', corpus_id=corpus.id)}, 201)
         else:
@@ -205,6 +215,11 @@ def add_corpus_file(corpus_id):
         corpus.status = 'unprepared'
         db.session.commit()
         flash('Corpus file "{}" added!'.format(corpus_file.filename), 'corpus')
+        event = 'user_{}_patch'.format(corpus.user_id)
+        jsonpatch = [{'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status},  # noqa
+                     {'op': 'add', 'path': '/corpora/{}/files/{}'.format(corpus.id, corpus_file.id), 'value': corpus_file.to_dict()}]  # noqa
+        room = 'user_{}'.format(corpus.user_id)
+        socketio.emit(event, jsonpatch, room=room)
         return make_response({'redirect_url': url_for('.corpus', corpus_id=corpus.id)}, 201)  # noqa
     return render_template('corpora/add_corpus_file.html.j2', corpus=corpus,
                            form=form, title='Add corpus file')
diff --git a/web/app/events.py b/web/app/events.py
index a0f76b3b..72cdef66 100644
--- a/web/app/events.py
+++ b/web/app/events.py
@@ -1,73 +1,72 @@
-from flask import current_app, request
+from flask import request
 from flask_login import current_user
-from . import db, socketio
-from .decorators import socketio_admin_required, socketio_login_required
+from flask_socketio import join_room, leave_room
+from . import socketio
+from .decorators import socketio_login_required
 from .models import User
-import json
-import jsonpatch
 
 
+###############################################################################
+# Socket.IO event handlers                                                    #
+###############################################################################
 '''
 ' A list containing session ids of connected Socket.IO sessions, to keep track
-' of all connected sessions, which is used to determine the runtimes of
+' of all connected sessions, which can be used to determine the runtimes of
 ' associated background tasks.
 '''
-connected_sessions = []
+socketio_sessions = []
 
 
 @socketio.on('connect')
-def connect():
+@socketio_login_required
+def socketio_connect():
     '''
     ' The Socket.IO module creates a session id (sid) for each request.
     ' On connect the sid is saved in the connected sessions list.
     '''
-    connected_sessions.append(request.sid)
+    socketio_sessions.append(request.sid)
 
 
 @socketio.on('disconnect')
-def disconnect():
+def socketio_disconnect():
     '''
     ' On disconnect the session id gets removed from the connected sessions
     ' list.
     '''
-    connected_sessions.remove(request.sid)
+    socketio_sessions.remove(request.sid)
 
 
 @socketio.on('start_user_session')
 @socketio_login_required
-def start_user_session(user_id):
-    if not (current_user.id == user_id or current_user.is_administrator):
-        return
-    socketio.start_background_task(user_session,
-                                   current_app._get_current_object(),
-                                   user_id, request.sid)
+def socketio_start_user_session(user_id):
+    user = User.query.get(user_id)
+    if user is None:
+        response = {'code': 404, 'msg': 'Not found'}
+        socketio.emit('start_user_session', response, room=request.sid)
+    elif not (user == current_user or current_user.is_administrator):
+        response = {'code': 403, 'msg': 'Forbidden'}
+        socketio.emit('start_user_session', response, room=request.sid)
+    else:
+        response = {'code': 200, 'msg': 'OK'}
+        socketio.emit('start_user_session', response, room=request.sid)
+        socketio.emit('user_{}_init'.format(user.id), user.to_dict(),
+                      room=request.sid)
+        room = 'user_{}'.format(user.id)
+        join_room(room)
 
 
-def user_session(app, user_id, session_id):
-    '''
-    ' Sends initial user data to the client. Afterwards it checks every 3s if
-    ' changes to the initial values appeared. If changes are detected, a
-    ' RFC 6902 compliant JSON patch gets send.
-    '''
-    init_event = 'user_{}_init'.format(user_id)
-    patch_event = 'user_{}_patch'.format(user_id)
-    with app.app_context():
-        # Gather current values from database.
-        user = User.query.get(user_id)
-        user_dict = user.to_dict()
-        # Send initial values to the client.
-        socketio.emit(init_event, json.dumps(user_dict), room=session_id)
-        while session_id in connected_sessions:
-            # Get new values from the database
-            db.session.refresh(user)
-            new_user_dict = user.to_dict()
-            # Compute JSON patches.
-            user_patch = jsonpatch.JsonPatch.from_diff(user_dict,
-                                                       new_user_dict)
-            # In case there are patches, send them to the client.
-            if user_patch:
-                socketio.emit(patch_event, user_patch.to_string(),
-                              room=session_id)
-            # Set new values as references for the next iteration.
-            user_dict = new_user_dict
-            socketio.sleep(3)
+@socketio.on('stop_user_session')
+@socketio_login_required
+def socketio_stop_user_session(user_id):
+    user = User.query.get(user_id)
+    if user is None:
+        response = {'code': 404, 'msg': 'Not found'}
+        socketio.emit('stop_user_session', response, room=request.sid)
+    elif not (user == current_user or current_user.is_administrator):
+        response = {'code': 403, 'msg': 'Forbidden'}
+        socketio.emit('stop_user_session', response, room=request.sid)
+    else:
+        response = {'code': 200, 'msg': 'OK'}
+        socketio.emit('stop_user_session', response, room=request.sid)
+        room = 'user_{}'.format(user.id)
+        leave_room(room)
diff --git a/web/app/jobs/tasks.py b/web/app/jobs/tasks.py
index 8ab823dc..fb4223b8 100644
--- a/web/app/jobs/tasks.py
+++ b/web/app/jobs/tasks.py
@@ -1,4 +1,4 @@
-from .. import db
+from .. import db, socketio
 from ..decorators import background
 from ..models import Job
 
@@ -9,8 +9,12 @@ def delete_job(job_id, *args, **kwargs):
         job = Job.query.get(job_id)
         if job is None:
             raise Exception('Job {} not found'.format(job_id))
+        event = 'user_{}_patch'.format(job.user_id)
+        jsonpatch = [{'op': 'remove', 'path': '/jobs/{}'.format(job.id)}]
+        room = 'user_{}'.format(job.user_id)
         job.delete()
         db.session.commit()
+        socketio.emit(event, jsonpatch, room=room)
 
 
 @background
@@ -19,5 +23,14 @@ def restart_job(job_id, *args, **kwargs):
         job = Job.query.get(job_id)
         if job is None:
             raise Exception('Job {} not found'.format(job_id))
-        job.restart()
-        db.session.commit()
+        try:
+            job.restart()
+        except Exception:
+            pass
+        else:
+            db.session.commit()
+            event = 'user_{}_patch'.format(job.user_id)
+            jsonpatch = [{'op': 'replace', 'path': '/jobs/{}/end_date'.format(job.id), 'value': job.end_date.timestamp()},  # noqa
+                         {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}]  # noqa
+            room = 'user_{}'.format(job.user_id)
+            socketio.emit(event, jsonpatch, room=room)
diff --git a/web/app/services/views.py b/web/app/services/views.py
index bd4bf3fa..1d81e6a8 100644
--- a/web/app/services/views.py
+++ b/web/app/services/views.py
@@ -2,7 +2,7 @@ from flask import abort, flash, make_response, render_template, url_for
 from flask_login import current_user, login_required
 from werkzeug.utils import secure_filename
 from . import services
-from .. import db
+from .. import db, socketio
 from ..jobs.forms import AddFileSetupJobForm, AddNLPJobForm, AddOCRJobForm
 from ..models import Job, JobInput
 import json
@@ -70,6 +70,10 @@ def service(service):
             job.status = 'submitted'
             db.session.commit()
             flash('Job "{}" added'.format(job.title), 'job')
+            event = 'user_{}_patch'.format(job.user_id)
+            jsonpatch = [{'op': 'add', 'path': '/jobs/{}'.format(job.id), 'value': job.to_dict()}]  # noqa
+            room = 'user_{}'.format(job.user_id)
+            socketio.emit(event, jsonpatch, room=room)
             return make_response(
                 {'redirect_url': url_for('jobs.job', job_id=job.id)}, 201)
     return render_template('services/{}.html.j2'.format(service),
diff --git a/web/app/static/js/nopaque/main.js b/web/app/static/js/nopaque/main.js
index c8f886be..6435186f 100644
--- a/web/app/static/js/nopaque/main.js
+++ b/web/app/static/js/nopaque/main.js
@@ -9,8 +9,8 @@ class AppClient {
     if (userId in this.users) {return this.users[userId];}
     let user = new User();
     this.users[userId] = user;
-    this.socket.on(`user_${userId}_init`, msg => user.init(JSON.parse(msg)));
-    this.socket.on(`user_${userId}_patch`, msg => user.patch(JSON.parse(msg)));
+    this.socket.on(`user_${userId}_init`, msg => user.init(msg));
+    this.socket.on(`user_${userId}_patch`, msg => user.patch(msg));
     this.socket.emit('start_user_session', userId);
     return user;
   }
@@ -40,40 +40,44 @@ class User {
   }
 
   init(data) {
+    console.log('### User.init ###');
+    console.log(data);
     this.data = data;
 
     for (let [corpusId, eventListeners] of Object.entries(this.eventListeners.corpus)) {
       if (corpusId === '*') {
-        for (let eventListener of eventListeners) {eventListener('init', this.data.corpora);}
+        for (let eventListener of eventListeners) {eventListener('init');}
       } else {
         if (corpusId in this.data.corpora) {
-          for (let eventListener of eventListeners) {eventListener('init', this.data.corpora[corpusId]);}
+          for (let eventListener of eventListeners) {eventListener('init');}
         }
       }
     }
 
     for (let [jobId, eventListeners] of Object.entries(this.eventListeners.job)) {
       if (jobId === '*') {
-        for (let eventListener of eventListeners) {eventListener('init', this.data.jobs);}
+        for (let eventListener of eventListeners) {eventListener('init');}
       } else {
         if (jobId in this.data.jobs) {
-          for (let eventListener of eventListeners) {eventListener('init', this.data.jobs[jobId]);}
+          for (let eventListener of eventListeners) {eventListener('init');}
         }
       }
     }
 
     for (let [queryResultId, eventListeners] of Object.entries(this.eventListeners.queryResult)) {
       if (queryResultId === '*') {
-        for (let eventListener of eventListeners) {eventListener('init', this.data.query_results);}
+        for (let eventListener of eventListeners) {eventListener('init');}
       } else {
         if (queryResultId in this.data.query_results) {
-          for (let eventListener of eventListeners) {eventListener('init', this.data.query_results[queryResultId]);}
+          for (let eventListener of eventListeners) {eventListener('init');}
         }
       }
     }
   }
 
   patch(patch) {
+    console.log('### User.patch ###');
+    console.log(patch);
     this.data = jsonpatch.apply_patch(this.data, patch);
 
     let corporaPatch = patch.filter(operation => operation.path.startsWith("/corpora"));
diff --git a/web/app/tasks/__init__.py b/web/app/tasks/__init__.py
index 154841b7..d19a4b8f 100644
--- a/web/app/tasks/__init__.py
+++ b/web/app/tasks/__init__.py
@@ -1,31 +1,57 @@
-from .. import db
-from ..models import Corpus, Job
+from .corpus_utils import CheckCorporaMixin
+from .job_utils import CheckJobsMixin
+from ..import db, socketio
 import docker
 
 
-docker_client = docker.from_env()
-from . import corpus_utils, job_utils  # noqa
+class TaskRunner(CheckCorporaMixin, CheckJobsMixin):
+    def __init__(self):
+        self.docker = docker.from_env()
+        self._socketio_message_buffer = {}
+
+    def run(self):
+        self.check_corpora()
+        self.check_jobs()
+        db.session.commit()
+        self.flush_socketio_messages()
+
+    def buffer_socketio_message(self, event, payload, room,
+                                msg_id=None, override_policy='replace'):
+        if room not in self._socketio_message_buffer:
+            self._socketio_message_buffer[room] = {}
+        if event not in self._socketio_message_buffer[room]:
+            self._socketio_message_buffer[room][event] = {}
+        if msg_id is None:
+            msg_id = len(self._socketio_message_buffer[room][event].keys())
+        if override_policy == 'append':
+            if msg_id in self._socketio_message_buffer[room][event]:
+                # If the current message value isn't a list, convert it!
+                if not isinstance(self._socketio_message_buffer[room][event][msg_id], list):  # noqa
+                    self._socketio_message_buffer[room][event][msg_id] = [self._socketio_message_buffer[room][event][msg_id]]  # noqa
+            else:
+                self._socketio_message_buffer[room][event][msg_id] = []
+            self._socketio_message_buffer[room][event][msg_id].append(payload)
+        elif override_policy == 'replace':
+            self._socketio_message_buffer[room][event][msg_id] = payload
+        else:
+            raise Exception('Unknown override policy: {}'.format(override_policy))  # noqa
+        return msg_id
+
+    def buffer_user_patch_operation(self, ressource, patch_operation):
+        self.buffer_socketio_message('user_{}_patch'.format(ressource.user_id),
+                                     patch_operation,
+                                     'user_{}'.format(ressource.user_id),
+                                     msg_id='_', override_policy='append')
+
+    def clear_socketio_message_buffer(self):
+        self._socketio_message_buffer = {}
+
+    def flush_socketio_messages(self):
+        for room in self._socketio_message_buffer:
+            for event in self._socketio_message_buffer[room]:
+                for message in self._socketio_message_buffer[room][event]:
+                    socketio.emit(event, self._socketio_message_buffer[room][event][message], room=room)  # noqa
+        self.clear_socketio_message_buffer()
 
 
-def check_corpora():
-    corpora = Corpus.query.all()
-    for corpus in filter(lambda corpus: corpus.status == 'submitted', corpora):
-        corpus_utils.create_build_corpus_service(corpus)
-    for corpus in filter(lambda corpus: corpus.status in ['queued', 'running'], corpora):  # noqa
-        corpus_utils.checkout_build_corpus_service(corpus)
-    for corpus in filter(lambda corpus: corpus.status == 'start analysis', corpora):  # noqa
-        corpus_utils.create_cqpserver_container(corpus)
-    for corpus in filter(lambda corpus: corpus.status == 'stop analysis', corpora):  # noqa
-        corpus_utils.remove_cqpserver_container(corpus)
-    db.session.commit()
-
-
-def check_jobs():
-    jobs = Job.query.all()
-    for job in filter(lambda job: job.status == 'submitted', jobs):
-        job_utils.create_job_service(job)
-    for job in filter(lambda job: job.status in ['queued', 'running'], jobs):
-        job_utils.checkout_job_service(job)
-    for job in filter(lambda job: job.status == 'canceling', jobs):
-        job_utils.remove_job_service(job)
-    db.session.commit()
+task_runner = TaskRunner()
diff --git a/web/app/tasks/corpus_utils.py b/web/app/tasks/corpus_utils.py
index 2167da46..5d51f342 100644
--- a/web/app/tasks/corpus_utils.py
+++ b/web/app/tasks/corpus_utils.py
@@ -1,174 +1,204 @@
-from . import docker_client
+from ..models import Corpus
 import docker
 import logging
 import os
 import shutil
 
 
-def create_build_corpus_service(corpus):
-    corpus_data_dir = os.path.join(corpus.path, 'data')
-    shutil.rmtree(corpus_data_dir, ignore_errors=True)
-    os.mkdir(corpus_data_dir)
-    corpus_registry_dir = os.path.join(corpus.path, 'registry')
-    shutil.rmtree(corpus_registry_dir, ignore_errors=True)
-    os.mkdir(corpus_registry_dir)
-    corpus_file = os.path.join(corpus.path, 'merged', 'corpus.vrt')
-    service_kwargs = {
-        'command': 'docker-entrypoint.sh build-corpus',
-        'constraints': ['node.role==worker'],
-        'labels': {'origin': 'nopaque',
-                   'type': 'corpus.build',
-                   'corpus_id': str(corpus.id)},
-        'mounts': [corpus_file + ':/root/files/corpus.vrt:ro',
-                   corpus_data_dir + ':/corpora/data:rw',
-                   corpus_registry_dir + ':/usr/local/share/cwb/registry:rw'],
-        'name': 'build-corpus_{}'.format(corpus.id),
-        'restart_policy': docker.types.RestartPolicy()
-    }
-    service_image = \
-        'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/cqpserver:latest'
-    try:
-        docker_client.services.create(service_image, **service_kwargs)
-    except docker.errors.APIError as e:
-        logging.error(
-            'Create "{}" service raised '.format(service_kwargs['name'])
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-    else:
-        corpus.status = 'queued'
+class CheckCorporaMixin:
+    def check_corpora(self):
+        corpora = Corpus.query.all()
+        queued_corpora = list(filter(lambda corpus: corpus.status == 'queued', corpora))
+        running_corpora = list(filter(lambda corpus: corpus.status == 'running', corpora))
+        start_analysis_corpora = list(filter(lambda corpus: corpus.status == 'start analysis', corpora))
+        stop_analysis_corpora = list(filter(lambda corpus: corpus.status == 'stop analysis', corpora))
+        submitted_corpora = list(filter(lambda corpus: corpus.status == 'submitted', corpora))
+        for corpus in submitted_corpora:
+            self.create_build_corpus_service(corpus)
+        for corpus in queued_corpora + running_corpora:
+            self.checkout_build_corpus_service(corpus)
+        for corpus in start_analysis_corpora:
+            self.create_cqpserver_container(corpus)
+        for corpus in stop_analysis_corpora:
+            self.remove_cqpserver_container(corpus)
 
+    def create_build_corpus_service(self, corpus):
+        corpus_data_dir = os.path.join(corpus.path, 'data')
+        shutil.rmtree(corpus_data_dir, ignore_errors=True)
+        os.mkdir(corpus_data_dir)
+        corpus_registry_dir = os.path.join(corpus.path, 'registry')
+        shutil.rmtree(corpus_registry_dir, ignore_errors=True)
+        os.mkdir(corpus_registry_dir)
+        corpus_file = os.path.join(corpus.path, 'merged', 'corpus.vrt')
+        service_kwargs = {
+            'command': 'docker-entrypoint.sh build-corpus',
+            'constraints': ['node.role==worker'],
+            'labels': {'origin': 'nopaque',
+                       'type': 'corpus.build',
+                       'corpus_id': str(corpus.id)},
+            'mounts': [corpus_file + ':/root/files/corpus.vrt:ro',
+                       corpus_data_dir + ':/corpora/data:rw',
+                       corpus_registry_dir + ':/usr/local/share/cwb/registry:rw'],
+            'name': 'build-corpus_{}'.format(corpus.id),
+            'restart_policy': docker.types.RestartPolicy()
+        }
+        service_image = \
+            'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/cqpserver:latest'
+        try:
+            self.docker.services.create(service_image, **service_kwargs)
+        except docker.errors.APIError as e:
+            logging.error(
+                'Create "{}" service raised '.format(service_kwargs['name'])
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
+        else:
+            corpus.status = 'queued'
+            patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+            self.buffer_user_patch_operation(corpus, patch_operation)
 
-def checkout_build_corpus_service(corpus):
-    service_name = 'build-corpus_{}'.format(corpus.id)
-    try:
-        service = docker_client.services.get(service_name)
-    except docker.errors.NotFound:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.NotFound" The service does not exist. '
-            + '(corpus.status: {} -> failed)'.format(corpus.status)
-        )
-        corpus.status = 'failed'
-    except docker.errors.APIError as e:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-    except docker.errors.InvalidVersion:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.InvalidVersion" One of the arguments is '
-            + 'not supported with the current API version.'
-        )
-    else:
-        service_tasks = service.tasks()
-        if not service_tasks:
+    def checkout_build_corpus_service(self, corpus):
+        service_name = 'build-corpus_{}'.format(corpus.id)
+        try:
+            service = self.docker.services.get(service_name)
+        except docker.errors.NotFound:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.NotFound" The service does not exist. '
+                + '(corpus.status: {} -> failed)'.format(corpus.status)
+            )
+            corpus.status = 'failed'
+            patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+            self.buffer_user_patch_operation(corpus, patch_operation)
+        except docker.errors.APIError as e:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
+        except docker.errors.InvalidVersion:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.InvalidVersion" One of the arguments is '
+                + 'not supported with the current API version.'
+            )
+        else:
+            service_tasks = service.tasks()
+            if not service_tasks:
+                return
+            task_state = service_tasks[0].get('Status').get('State')
+            if corpus.status == 'queued' and task_state != 'pending':
+                corpus.status = 'running'
+                patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+                self.buffer_user_patch_operation(corpus, patch_operation)
+            elif (corpus.status == 'running'
+                  and task_state in ['complete', 'failed']):
+                try:
+                    service.remove()
+                except docker.errors.APIError as e:
+                    logging.error(
+                        'Remove "{}" service raised '.format(service_name)
+                        + '"docker.errors.APIError" The server returned an error. '
+                        + 'Details: {}'.format(e)
+                    )
+                    return
+                else:
+                    corpus.status = 'prepared' if task_state == 'complete' \
+                                    else 'failed'
+                    patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+                    self.buffer_user_patch_operation(corpus, patch_operation)
+
+    def create_cqpserver_container(self, corpus):
+        corpus_data_dir = os.path.join(corpus.path, 'data')
+        corpus_registry_dir = os.path.join(corpus.path, 'registry')
+        container_kwargs = {
+            'command': 'cqpserver',
+            'detach': True,
+            'volumes': [corpus_data_dir + ':/corpora/data:rw',
+                        corpus_registry_dir + ':/usr/local/share/cwb/registry:rw'],
+            'name': 'cqpserver_{}'.format(corpus.id),
+            'network': 'nopaque_default'
+        }
+        container_image = \
+            'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/cqpserver:latest'
+        # Check if a cqpserver container already exists. If this is the case,
+        # remove it and create a new one
+        try:
+            container = self.docker.containers.get(container_kwargs['name'])
+        except docker.errors.NotFound:
+            pass
+        except docker.errors.APIError as e:
+            logging.error(
+                'Get "{}" container raised '.format(container_kwargs['name'])
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
             return
-        task_state = service_tasks[0].get('Status').get('State')
-        if corpus.status == 'queued' and task_state != 'pending':
-            corpus.status = 'running'
-        elif (corpus.status == 'running'
-              and task_state in ['complete', 'failed']):
+        else:
             try:
-                service.remove()
+                container.remove(force=True)
             except docker.errors.APIError as e:
                 logging.error(
-                    'Remove "{}" service raised '.format(service_name)
+                    'Remove "{}" container raised '.format(container_kwargs['name'])
                     + '"docker.errors.APIError" The server returned an error. '
                     + 'Details: {}'.format(e)
                 )
                 return
-            else:
-                corpus.status = 'prepared' if task_state == 'complete' \
-                                else 'failed'
-
-
-def create_cqpserver_container(corpus):
-    corpus_data_dir = os.path.join(corpus.path, 'data')
-    corpus_registry_dir = os.path.join(corpus.path, 'registry')
-    container_kwargs = {
-        'command': 'cqpserver',
-        'detach': True,
-        'volumes': [corpus_data_dir + ':/corpora/data:rw',
-                    corpus_registry_dir + ':/usr/local/share/cwb/registry:rw'],
-        'name': 'cqpserver_{}'.format(corpus.id),
-        'network': 'nopaque_default'
-    }
-    container_image = \
-        'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/cqpserver:latest'
-    # Check if a cqpserver container already exists. If this is the case,
-    # remove it and create a new one
-    try:
-        container = docker_client.containers.get(container_kwargs['name'])
-    except docker.errors.NotFound:
-        pass
-    except docker.errors.APIError as e:
-        logging.error(
-            'Get "{}" container raised '.format(container_kwargs['name'])
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-        return
-    else:
         try:
-            container.remove(force=True)
+            self.docker.containers.run(container_image, **container_kwargs)
+        except docker.errors.ContainerError:
+            # This case should not occur, because detach is True.
+            logging.error(
+                'Run "{}" container raised '.format(container_kwargs['name'])
+                + '"docker.errors.ContainerError" The container exits with a '
+                + 'non-zero exit code and detach is False.'
+            )
+            corpus.status = 'failed'
+            patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+            self.buffer_user_patch_operation(corpus, patch_operation)
+        except docker.errors.ImageNotFound:
+            logging.error(
+                'Run "{}" container raised '.format(container_kwargs['name'])
+                + '"docker.errors.ImageNotFound" The specified image does not '
+                + 'exist.'
+            )
+            corpus.status = 'failed'
+            patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+            self.buffer_user_patch_operation(corpus, patch_operation)
         except docker.errors.APIError as e:
             logging.error(
-                'Remove "{}" container raised '.format(container_kwargs['name'])  # noqa
+                'Run "{}" container raised '.format(container_kwargs['name'])
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
+        else:
+            corpus.status = 'analysing'
+            patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+            self.buffer_user_patch_operation(corpus, patch_operation)
+
+    def remove_cqpserver_container(self, corpus):
+        container_name = 'cqpserver_{}'.format(corpus.id)
+        try:
+            container = self.docker.containers.get(container_name)
+        except docker.errors.NotFound:
+            pass
+        except docker.errors.APIError as e:
+            logging.error(
+                'Get "{}" container raised '.format(container_name)
                 + '"docker.errors.APIError" The server returned an error. '
                 + 'Details: {}'.format(e)
             )
             return
-    try:
-        docker_client.containers.run(container_image, **container_kwargs)
-    except docker.errors.ContainerError:
-        # This case should not occur, because detach is True.
-        logging.error(
-            'Run "{}" container raised '.format(container_kwargs['name'])
-            + '"docker.errors.ContainerError" The container exits with a '
-            + 'non-zero exit code and detach is False.'
-        )
-        corpus.status = 'failed'
-    except docker.errors.ImageNotFound:
-        logging.error(
-            'Run "{}" container raised '.format(container_kwargs['name'])
-            + '"docker.errors.ImageNotFound" The specified image does not '
-            + 'exist.'
-        )
-        corpus.status = 'failed'
-    except docker.errors.APIError as e:
-        logging.error(
-            'Run "{}" container raised '.format(container_kwargs['name'])
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-    else:
-        corpus.status = 'analysing'
-
-
-def remove_cqpserver_container(corpus):
-    container_name = 'cqpserver_{}'.format(corpus.id)
-    try:
-        container = docker_client.containers.get(container_name)
-    except docker.errors.NotFound:
-        pass
-    except docker.errors.APIError as e:
-        logging.error(
-            'Get "{}" container raised '.format(container_name)
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-        return
-    else:
-        try:
-            container.remove(force=True)
-        except docker.errors.APIError as e:
-            logging.error(
-                'Remove "{}" container raised '.format(container_name)
-                + '"docker.errors.APIError" The server returned an error. '
-                + 'Details: {}'.format(e)
-            )
-            return
-    corpus.status = 'prepared'
+        else:
+            try:
+                container.remove(force=True)
+            except docker.errors.APIError as e:
+                logging.error(
+                    'Remove "{}" container raised '.format(container_name)
+                    + '"docker.errors.APIError" The server returned an error. '
+                    + 'Details: {}'.format(e)
+                )
+                return
+        corpus.status = 'prepared'
+        patch_operation = {'op': 'replace', 'path': '/corpora/{}/status'.format(corpus.id), 'value': corpus.status}
+        self.buffer_user_patch_operation(corpus, patch_operation)
diff --git a/web/app/tasks/job_utils.py b/web/app/tasks/job_utils.py
index 19a75b81..e2635dda 100644
--- a/web/app/tasks/job_utils.py
+++ b/web/app/tasks/job_utils.py
@@ -1,82 +1,161 @@
 from datetime import datetime
 from werkzeug.utils import secure_filename
-from . import docker_client
 from .. import db, mail
 from ..email import create_message
-from ..models import JobResult
+from ..models import Job, JobResult
 import docker
 import logging
 import json
 import os
 
 
-def create_job_service(job):
-    cmd = '{} -i /files -o /files/output'.format(job.service)
-    if job.service == 'file-setup':
-        cmd += ' -f {}'.format(secure_filename(job.title))
-    cmd += ' --log-dir /files'
-    cmd += ' --zip [{}]_{}'.format(job.service, secure_filename(job.title))
-    cmd += ' ' + ' '.join(json.loads(job.service_args))
-    service_kwargs = {'command': cmd,
-                      'constraints': ['node.role==worker'],
-                      'labels': {'origin': 'nopaque',
-                                 'type': 'service.{}'.format(job.service),
-                                 'job_id': str(job.id)},
-                      'mounts': [job.path + ':/files:rw'],
-                      'name': 'job_{}'.format(job.id),
-                      'resources': docker.types.Resources(
-                          cpu_reservation=job.n_cores * (10 ** 9),
-                          mem_reservation=job.mem_mb * (10 ** 6)
-                      ),
-                      'restart_policy': docker.types.RestartPolicy()}
-    service_image = 'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/{}:{}'.format(
-        job.service, job.service_version)
-    try:
-        docker_client.services.create(service_image, **service_kwargs)
-    except docker.errors.APIError as e:
-        logging.error(
-            'Create "{}" service raised '.format(service_kwargs['name'])
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-        return
-    else:
-        job.status = 'queued'
-    finally:
-        send_notification(job)
+class CheckJobsMixin:
+    def check_jobs(self):
+        jobs = Job.query.all()
+        canceling_jobs = list(filter(lambda job: job.status == 'canceling', jobs))
+        queued_jobs = list(filter(lambda job: job.status == 'queued', jobs))
+        running_jobs = list(filter(lambda job: job.status == 'running', jobs))
+        submitted_jobs = list(filter(lambda job: job.status == 'submitted', jobs))
+        for job in submitted_jobs:
+            self.create_job_service(job)
+        for job in queued_jobs + running_jobs:
+            self.checkout_job_service(job)
+        for job in canceling_jobs:
+            self.remove_job_service(job)
 
-
-def checkout_job_service(job):
-    service_name = 'job_{}'.format(job.id)
-    try:
-        service = docker_client.services.get(service_name)
-    except docker.errors.NotFound:
-        logging.error('Get "{}" service raised '.format(service_name)
-                      + '"docker.errors.NotFound" The service does not exist. '
-                      + '(job.status: {} -> failed)'.format(job.status))
-        job.status = 'failed'
-    except docker.errors.APIError as e:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-        return
-    except docker.errors.InvalidVersion:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.InvalidVersion" One of the arguments is '
-            + 'not supported with the current API version.'
-        )
-        return
-    else:
-        service_tasks = service.tasks()
-        if not service_tasks:
+    def create_job_service(self, job):
+        cmd = '{} -i /files -o /files/output'.format(job.service)
+        if job.service == 'file-setup':
+            cmd += ' -f {}'.format(secure_filename(job.title))
+        cmd += ' --log-dir /files'
+        cmd += ' --zip [{}]_{}'.format(job.service, secure_filename(job.title))
+        cmd += ' ' + ' '.join(json.loads(job.service_args))
+        service_kwargs = {'command': cmd,
+                          'constraints': ['node.role==worker'],
+                          'labels': {'origin': 'nopaque',
+                                     'type': 'service.{}'.format(job.service),
+                                     'job_id': str(job.id)},
+                          'mounts': [job.path + ':/files:rw'],
+                          'name': 'job_{}'.format(job.id),
+                          'resources': docker.types.Resources(
+                              cpu_reservation=job.n_cores * (10 ** 9),
+                              mem_reservation=job.mem_mb * (10 ** 6)
+                          ),
+                          'restart_policy': docker.types.RestartPolicy()}
+        service_image = 'gitlab.ub.uni-bielefeld.de:4567/sfb1288inf/{}:{}'.format(job.service, job.service_version)
+        try:
+            self.docker.services.create(service_image, **service_kwargs)
+        except docker.errors.APIError as e:
+            logging.error(
+                'Create "{}" service raised '.format(service_kwargs['name'])
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
             return
-        task_state = service_tasks[0].get('Status').get('State')
-        if job.status == 'queued' and task_state != 'pending':
-            job.status = 'running'
-        elif job.status == 'running' and task_state in ['complete', 'failed']:
+        else:
+            job.status = 'queued'
+            patch_operation = {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}
+            self.buffer_user_patch_operation(job, patch_operation)
+        finally:
+            self.send_job_notification(job)
+
+    def checkout_job_service(self, job):
+        service_name = 'job_{}'.format(job.id)
+        try:
+            service = self.docker.services.get(service_name)
+        except docker.errors.NotFound:
+            logging.error('Get "{}" service raised '.format(service_name)
+                          + '"docker.errors.NotFound" The service does not exist. '
+                          + '(job.status: {} -> failed)'.format(job.status))
+            job.status = 'failed'
+            patch_operation = {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}
+            self.buffer_user_patch_operation(job, patch_operation)
+        except docker.errors.APIError as e:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
+            return
+        except docker.errors.InvalidVersion:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.InvalidVersion" One of the arguments is '
+                + 'not supported with the current API version.'
+            )
+            return
+        else:
+            service_tasks = service.tasks()
+            if not service_tasks:
+                return
+            task_state = service_tasks[0].get('Status').get('State')
+            if job.status == 'queued' and task_state != 'pending':
+                job.status = 'running'
+                patch_operation = {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}
+                self.buffer_user_patch_operation(job, patch_operation)
+            elif job.status == 'running' and task_state in ['complete', 'failed']:
+                try:
+                    service.remove()
+                except docker.errors.APIError as e:
+                    logging.error(
+                        'Remove "{}" service raised '.format(service_name)
+                        + '"docker.errors.APIError" The server returned an error. '
+                        + 'Details: {}'.format(e)
+                    )
+                    return
+                else:
+                    if task_state == 'complete':
+                        results_dir = os.path.join(job.path, 'output')
+                        result_files = filter(lambda x: x.endswith('.zip'),
+                                              os.listdir(results_dir))
+                        for result_file in result_files:
+                            job_result = JobResult(filename=result_file, job=job)
+                            db.session.add(job_result)
+                            db.session.flush()
+                            db.session.refresh(job_result)
+                            patch_operation = {'op': 'add', 'path': '/jobs/{}/results/{}'.format(job.id, job_result.id), 'value': job_result.to_dict()}
+                            self.buffer_user_patch_operation(job, patch_operation)
+                    job.end_date = datetime.utcnow()
+                    patch_operation = {'op': 'replace', 'path': '/jobs/{}/end_date'.format(job.id), 'value': job.end_date.timestamp()}
+                    self.buffer_user_patch_operation(job, patch_operation)
+                    job.status = task_state
+                    patch_operation = {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}
+                    self.buffer_user_patch_operation(job, patch_operation)
+        finally:
+            self.send_job_notification(job)
+
+    def remove_job_service(self, job):
+        service_name = 'job_{}'.format(job.id)
+        try:
+            service = self.docker.services.get(service_name)
+        except docker.errors.NotFound:
+            job.status = 'canceled'
+            patch_operation = {'op': 'replace', 'path': '/jobs/{}/status'.format(job.id), 'value': job.status}
+            self.buffer_user_patch_operation(job, patch_operation)
+        except docker.errors.APIError as e:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.APIError" The server returned an error. '
+                + 'Details: {}'.format(e)
+            )
+            return
+        except docker.errors.InvalidVersion:
+            logging.error(
+                'Get "{}" service raised '.format(service_name)
+                + '"docker.errors.InvalidVersion" One of the arguments is '
+                + 'not supported with the current API version.'
+            )
+            return
+        else:
+            try:
+                service.update(mounts=None)
+            except docker.errors.APIError as e:
+                logging.error(
+                    'Update "{}" service raised '.format(service_name)
+                    + '"docker.errors.APIError" The server returned an error. '
+                    + 'Details: {}'.format(e)
+                )
+                return
             try:
                 service.remove()
             except docker.errors.APIError as e:
@@ -85,68 +164,14 @@ def checkout_job_service(job):
                     + '"docker.errors.APIError" The server returned an error. '
                     + 'Details: {}'.format(e)
                 )
-                return
-            else:
-                if task_state == 'complete':
-                    job_results_dir = os.path.join(job.path, 'output')
-                    job_results = filter(lambda x: x.endswith('.zip'),
-                                         os.listdir(job_results_dir))
-                    for job_result in job_results:
-                        job_result = JobResult(filename=job_result, job=job)
-                        db.session.add(job_result)
-                job.end_date = datetime.utcnow()
-                job.status = task_state
-    finally:
-        send_notification(job)
 
-
-def remove_job_service(job):
-    service_name = 'job_{}'.format(job.id)
-    try:
-        service = docker_client.services.get(service_name)
-    except docker.errors.NotFound:
-        job.status = 'canceled'
-    except docker.errors.APIError as e:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.APIError" The server returned an error. '
-            + 'Details: {}'.format(e)
-        )
-        return
-    except docker.errors.InvalidVersion:
-        logging.error(
-            'Get "{}" service raised '.format(service_name)
-            + '"docker.errors.InvalidVersion" One of the arguments is '
-            + 'not supported with the current API version.'
-        )
-        return
-    else:
-        try:
-            service.update(mounts=None)
-        except docker.errors.APIError as e:
-            logging.error(
-                'Update "{}" service raised '.format(service_name)
-                + '"docker.errors.APIError" The server returned an error. '
-                + 'Details: {}'.format(e)
-            )
+    def send_job_notification(self, job):
+        if job.creator.setting_job_status_mail_notifications == 'none':
             return
-        try:
-            service.remove()
-        except docker.errors.APIError as e:
-            logging.error(
-                'Remove "{}" service raised '.format(service_name)
-                + '"docker.errors.APIError" The server returned an error. '
-                + 'Details: {}'.format(e)
-            )
-
-
-def send_notification(job):
-    if job.creator.setting_job_status_mail_notifications == 'none':
-        return
-    if (job.creator.setting_job_status_mail_notifications == 'end'
-            and job.status not in ['complete', 'failed']):
-        return
-    msg = create_message(job.creator.email,
-                         'Status update for your Job "{}"'.format(job.title),
-                         'tasks/email/notification', job=job)
-    mail.send(msg)
+        if (job.creator.setting_job_status_mail_notifications == 'end'
+                and job.status not in ['complete', 'failed']):
+            return
+        msg = create_message(job.creator.email,
+                             'Status update for your Job "{}"'.format(job.title),
+                             'tasks/email/notification', job=job)
+        mail.send(msg)
diff --git a/web/nopaque.py b/web/nopaque.py
index 5c5c5af5..16662a23 100644
--- a/web/nopaque.py
+++ b/web/nopaque.py
@@ -50,9 +50,8 @@ def deploy():
 
 @app.cli.command()
 def tasks():
-    from app.tasks import check_corpora, check_jobs
-    check_corpora()
-    check_jobs()
+    from app.tasks import task_runner
+    task_runner.run()
 
 
 @app.cli.command()