While I was writing simple message-based fileserver and client, I got the idea about checking fileserver status, but don't know how to realize this: just try to connect and disconnect from server (and how disconnect immediately, when server is not running, if using this way?) or maybe twisted/autobahn have some things, which help to get server status without creating "full connection"?
a) fileserver.py
import os
import sys
import json
from twisted.internet import reactor
from autobahn.twisted.websocket import WebSocketServerFactory, WebSocketServerProtocol, listenWS
CONFIG_TEMPLATE = ''
CONFIG_DATA = {}
class MessageBasedServerProtocol(WebSocketServerProtocol):
"""
Message-based WebSockets server
Template contains some parts as string:
[USER_ID:OPERATION_NAME:FILE_ID] - 15 symbols for USER_ID,
10 symbols for OPERATION_NAME,
25 symbols for FILE_ID
other - some data
"""
def __init__(self):
path = CONFIG_DATA['path']
base_dir = CONFIG_DATA['base_dir']
# prepare to working with files...
if os.path.exists(path) and os.path.isdir(path):
os.chdir(path)
if not os.path.exists(base_dir) or not os.path.isdir(base_dir):
os.mkdir(base_dir)
os.chdir(base_dir)
else:
os.makedir(path)
os.chdir(path)
os.mkdir(base_dir)
os.chdir(base_dir)
# init some things
self.fullpath = path + '/' + base_dir
def __checkUserCatalog(self, user_id):
# prepare to working with files...
os.chdir(self.fullpath)
if not os.path.exists(user_id) or not os.path.isdir(user_id):
os.mkdir(user_id)
os.chdir(user_id)
else:
os.chdir(self.fullpath + '/' + user_id)
def onOpen(self):
print "[USER] User with %s connected" % (self.transport.getPeer())
def connectionLost(self, reason):
print '[USER] Lost connection from %s' % (self.transport.getPeer())
def onMessage(self, payload, isBinary):
"""
Processing request from user and send response
"""
user_id, cmd, file_id = payload[:54].replace('[', '').replace(']','').split(':')
data = payload[54:]
operation = "UNK" # WRT - Write, REA -> Read, DEL -> Delete, UNK -> Unknown
status = "C" # C -> Complete, E -> Error in operation
commentary = 'Succesfull!'
# write file into user storage
if cmd == 'WRITE_FILE':
self.__checkUserCatalog(user_id)
operation = "WRT"
try:
f = open(file_id, "wb")
f.write(data)
except IOError, argument:
status = "E"
commentary = argument
except Exception, argument:
status = "E"
commentary = argument
raise Exception(argument)
finally:
f.close()
# read some file
elif cmd == 'READU_FILE':
self.__checkUserCatalog(user_id)
operation = "REA"
try:
f = open(file_id, "rb")
commentary = f.read()
except IOError, argument:
status = "E"
commentary = argument
except Exception, argument:
status = "E"
commentary = argument
raise Exception(argument)
finally:
f.close()
# delete file from storage (and in main server, in parallel delete from DB)
elif cmd == 'DELET_FILE':
self.__checkUserCatalog(user_id)
operation = "DEL"
try:
os.remove(file_id)
except IOError, argument:
status = "E"
commentary = argument
except Exception, argument:
status = "E"
commentary = argument
raise Exception(argument)
self.sendMessage('[%s][%s]%s' % (operation, status, commentary), isBinary=True)
if __name__ == '__main__':
if len(sys.argv) < 2:
print "using python fileserver_client.py [PATH_TO_config.json_FILE]"
else:
# read config file
CONFIG_TEMPLATE = sys.argv[1]
with open(CONFIG_TEMPLATE, "r") as f:
CONFIG_DATA = json.load(f)
# create server
factory = WebSocketServerFactory("ws://localhost:9000")
factory.protocol = MessageBasedServerProtocol
listenWS(factory)
reactor.run()
b) client.py
import json
import sys
import commands
from twisted.internet import reactor
from autobahn.twisted.websocket import WebSocketClientFactory, WebSocketClientProtocol, connectWS
CONFIG_TEMPLATE = ''
CONFIG_DATA = {}
class MessageBasedClientProtocol(WebSocketClientProtocol):
"""
Message-based WebSockets client
Template contains some parts as string:
[USER_ID:OPERATION_NAME:FILE_ID] - 15 symbols for USER_ID,
10 symbols for OPERATION_NAME,
25 symbols for FILE_ID
other - some data
"""
def onOpen(self):
user_id = CONFIG_DATA['user']
operation_name = CONFIG_DATA['cmd']
file_id = CONFIG_DATA['file_id']
src_file = CONFIG_DATA['src_file']
data = '[' + str(user_id) + ':' + str(operation_name) + ':' + str(file_id) + ']'
if operation_name == 'WRITE_FILE':
with open(src_file, "r") as f:
info = f.read()
data += str(info)
self.sendMessage(data, isBinary=True)
def onMessage(self, payload, isBinary):
cmd = payload[1:4]
result_cmd = payload[6]
if cmd in ('WRT', 'DEL'):
print payload
elif cmd == 'REA':
if result_cmd == 'C':
try:
data = payload[8:]
f = open(CONFIG_DATA['src_file'], "wb")
f.write(data)
except IOError, e:
print e
except Exception, e:
raise Exception(e)
finally:
print payload[:8] + "Successfully!"
f.close()
else:
print payload
reactor.stop()
if __name__ == '__main__':
if len(sys.argv) < 2:
print "using python fileserver_client.py [PATH_TO_config.json_FILE]"
else:
# read config file
CONFIG_TEMPLATE = sys.argv[1]
with open(CONFIG_TEMPLATE, "r") as f:
CONFIG_DATA = json.load(f)
# connection to server
factory = WebSocketClientFactory("ws://localhost:9000")
factory.protocol = MessageBasedClientProtocol
connectWS(factory)
reactor.run()
Find solution this issue: using callLater or deferLater for disconnect from server, if can't connect, but when all was 'OK', just take server status, which he says.
import sys
from twisted.internet.task import deferLater
from twisted.internet import reactor
from autobahn.twisted.websocket import WebSocketClientFactory, WebSocketClientProtocol, connectWS
CONFIG_IP = ''
CONFIG_PORT = 9000
def isOffline(status):
print status
class StatusCheckerProtocol(WebSocketClientProtocol):
def __init__(self):
self.operation_name = "STATUS_SRV"
self.user_id = 'u00000000000000'
self.file_id = "000000000000000000000.log"
def onOpen(self):
data = '[' + str(self.user_id) + ':' + str(self.operation_name) + ':' + str(self.file_id) + ']'
self.sendMessage(data, isBinary=True)
def onMessage(self, payload, isBinary):
cmd = payload[1:4]
result_cmd = payload[6]
data = payload[8:]
print data
reactor.stop()
if __name__ == '__main__':
if len(sys.argv) < 3:
print "using python statuschecker.py [IP] [PORT]"
else:
# read preferences
CONFIG_IP = sys.argv[1]
CONFIG_PORT = int(sys.argv[2])
server_addr = "ws://%s:%d" % (CONFIG_IP, CONFIG_PORT)
# connection to server
factory = WebSocketClientFactory(server_addr)
factory.protocol = StatusCheckerProtocol
connectWS(factory)
# create special Deffered, which disconnect us from some server, if can't connect within 3 seconds
d = deferLater(reactor, 3, isOffline, 'OFFLINE')
d.addCallback(lambda ignored: reactor.stop())
# run all system...
reactor.run()