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Asynchronous UI notification implementation
This patch makes backend and UI changes to implement the asynchronous UI notification in WoK. - Backend: A push server was implemented from scratch to manage the opened websocket connections. The push server connects to the /run/user/<user_id>/woknotifications UNIX socket and broadcasts all messages to all connections. The websocket module is the same module that exists in the Kimchi plug-in. The idea is to remove the module from Kimchi and make it use the module from WoK. ws_proxy initialization was also added in src/wok/server.py. A change were made in Wok base control classes to allow every call of log_request to also send a websocket notification in the following format: <METHOD>:/<plugin>/<entity>/<action> For example, creating a new user in Ginger would trigger the following websocket notification: 'POST:/ginger/users' - Frontend: In ui/js/wok.main.js two new functions were added to help the usage of asynchronous notifications in the frontend. The idea: a single websocket is opened per session. This opened websocket will broadcast all incoming messages to all listeners registered. Listeners can be added by the new wok.addNotificationListener() method. This method will clean up any registered listener by itself when the user changes tabs/URL. The single websocket sends heartbeats to the backend side each 30 seconds. No reply from the backend is issued or expected. This heartbeat is just a way to ensure that the browser does not close the connection due to inactivity. This behavior varies from browser to browser but this 30 second heartbeat is more than enough to ensure that the websocket is kept alive. - Working example in User Log: A simple usage is provided in this patch. Changes were made in the UI of the User Log feature to refresh the listing each time a new log entry websocket notification is received. The idea is to allow this code to be a working example of how other tabs can consume the asynchronous notifications. Signed-off-by: Daniel Henrique Barboza <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,164 @@ | ||
| # | ||
| # Project Wok | ||
| # | ||
| # Copyright IBM Corp, 2017 | ||
| # | ||
| # This library is free software; you can redistribute it and/or | ||
| # modify it under the terms of the GNU Lesser General Public | ||
| # License as published by the Free Software Foundation; either | ||
| # version 2.1 of the License, or (at your option) any later version. | ||
| # | ||
| # This library is distributed in the hope that it will be useful, | ||
| # but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| # Lesser General Public License for more details. | ||
| # | ||
| # You should have received a copy of the GNU Lesser General Public | ||
| # License along with this library; if not, write to the Free Software | ||
| # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| # | ||
|
|
||
| import cherrypy | ||
| import os | ||
| import select | ||
| import socket | ||
| import threading | ||
|
|
||
| import wok.websocket as websocket | ||
| from wok.config import get_pushserver_socket_dir | ||
| from wok.utils import wok_log | ||
|
|
||
|
|
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| BASE_DIRECTORY = get_pushserver_socket_dir() | ||
| TOKEN_NAME = 'woknotifications' | ||
| END_OF_MESSAGE_MARKER = '//EOM//' | ||
| push_server = None | ||
|
|
||
|
|
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| def start_push_server(): | ||
| global push_server | ||
|
|
||
| if not push_server: | ||
| push_server = PushServer() | ||
|
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|
|
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| def send_websocket_notification(message): | ||
| global push_server | ||
|
|
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| if push_server: | ||
| push_server.send_notification(message) | ||
|
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|
|
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| def send_wok_notification(uri, entity, method, action_name=None): | ||
| app_name = 'wok' | ||
| app = cherrypy.tree.apps.get(uri) | ||
| if app: | ||
| app_name = app.root.domain | ||
|
|
||
| source = '/%s/%s' % (app_name, entity) | ||
| if action_name: | ||
| source = '%s/%s' % (source, action_name) | ||
| message = '%s:%s' % (method, source) | ||
| send_websocket_notification(message) | ||
|
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|
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| class PushServer(object): | ||
|
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| def set_socket_file(self): | ||
| if not os.path.isdir(BASE_DIRECTORY): | ||
| try: | ||
| os.mkdir(BASE_DIRECTORY) | ||
| except OSError: | ||
| raise RuntimeError('PushServer base UNIX socket dir %s ' | ||
| 'not found.' % BASE_DIRECTORY) | ||
|
|
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| self.server_addr = os.path.join(BASE_DIRECTORY, TOKEN_NAME) | ||
|
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| if os.path.exists(self.server_addr): | ||
| try: | ||
| os.remove(self.server_addr) | ||
| except: | ||
| raise RuntimeError('There is an existing connection in %s' % | ||
| self.server_addr) | ||
|
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| def __init__(self): | ||
| self.set_socket_file() | ||
|
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| websocket.add_proxy_token(TOKEN_NAME, self.server_addr, True) | ||
|
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| self.connections = [] | ||
|
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| self.server_running = True | ||
| self.server_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) | ||
| self.server_socket.setsockopt(socket.SOL_SOCKET, | ||
| socket.SO_REUSEADDR, 1) | ||
| self.server_socket.bind(self.server_addr) | ||
| self.server_socket.listen(10) | ||
| wok_log.info('Push server created on address %s' % self.server_addr) | ||
|
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| self.connections.append(self.server_socket) | ||
| cherrypy.engine.subscribe('stop', self.close_server, 1) | ||
|
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| server_loop = threading.Thread(target=self.listen) | ||
| server_loop.setDaemon(True) | ||
| server_loop.start() | ||
|
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| def listen(self): | ||
| try: | ||
| while self.server_running: | ||
| read_ready, _, _ = select.select(self.connections, | ||
| [], [], 1) | ||
| for sock in read_ready: | ||
| if not self.server_running: | ||
| break | ||
|
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| if sock == self.server_socket: | ||
|
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| new_socket, addr = self.server_socket.accept() | ||
| self.connections.append(new_socket) | ||
| else: | ||
| try: | ||
| data = sock.recv(4096) | ||
| except: | ||
| try: | ||
| self.connections.remove(sock) | ||
| except ValueError: | ||
| pass | ||
|
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| continue | ||
| if data and data == 'CLOSE': | ||
| sock.send('ACK') | ||
| try: | ||
| self.connections.remove(sock) | ||
| except ValueError: | ||
| pass | ||
| sock.close() | ||
|
|
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| except Exception as e: | ||
| raise RuntimeError('Exception ocurred in listen() of pushserver ' | ||
| 'module: %s' % e.message) | ||
|
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| def send_notification(self, message): | ||
| message += END_OF_MESSAGE_MARKER | ||
| for sock in self.connections: | ||
| if sock != self.server_socket: | ||
| try: | ||
| sock.send(message) | ||
| except IOError as e: | ||
| if 'Broken pipe' in str(e): | ||
| sock.close() | ||
| try: | ||
| self.connections.remove(sock) | ||
| except ValueError: | ||
| pass | ||
|
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| def close_server(self): | ||
| try: | ||
| self.server_running = False | ||
| self.server_socket.shutdown(socket.SHUT_RDWR) | ||
| self.server_socket.close() | ||
| os.remove(self.server_addr) | ||
| except: | ||
| pass | ||
| finally: | ||
| cherrypy.engine.unsubscribe('stop', self.close_server) |
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