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import socket
import random
from pprint import pformat
from errno import EAGAIN
from Queue import Queue
from Queue import Empty as QueueEmpty
class UnknownBrokerResponseError(Exception):
"""An unexpected response was received from the broker."""
class BrokerErrorResponse(Exception):
"""Received error from the broker."""
class IntermediateMessageQueue(object):
"""Internal message queue that holds messages received by the server.
This to make sure a message isn't received instead of a command response
after issuing a receipt request.
"""
def __init__(self):
self._queue = Queue()
def put(self, frame):
"""Put a new frame onto the message queue.
:param frame: A :class:`Frame` instance.
"""
if "destination" not in frame.headers:
return
self._queue.put(frame)
def get(self, frame, nb=False):
"""Get a new frame from the message queue.
If no frame is available it try to get the next frame
from the socket.
:param frame: A :class:`Frame` instance.
:keyword nb: Non-blocking.
"""
try:
return self._queue.get_nowait()
except QueueEmpty:
return frame.parse_frame(nb=nb)
class Frame(object):
"""Build and manage a STOMP Frame.
:keyword sock: An open socket to the STOMP server.
"""
def __init__(self, sock=None):
self.command = None
self.headers = {}
self.body = None
self.session = None
self.my_name = socket.gethostbyname(socket.gethostname())
self.sock = sock
self.iqueue = IntermediateMessageQueue()
self.rqueue = Queue()
def connect(self, sock, username=None, password=None):
"""Connect to the STOMP server and get the session id.
:param sock: Socket object from stompy.stomp.Stomp.
:keyword username: Username for connection.
:keyword password: Password for connection.
"""
self.sock = sock
if username and password:
frame = self.build_frame({"command": "CONNECT",
"headers": {'login': username,
'passcode': password}})
else:
frame = self.build_frame({"command": "CONNECT", "headers": {}})
self.send_frame(frame.as_string())
# Get session from the next reply from the server.
next_frame = self.get_reply()
self.session = next_frame.headers
def build_frame(self, args, want_receipt=False):
"""Build a frame based on a :class:`dict` of arguments.
:param args: A :class:`dict` of arguments for the frame.
:keyword want_receipt: Optional argument to get a receipt from
the sever that the frame was received.
Example
>>> frame = frameobj.build_frame({"command": 'CONNECT',
"headers": {},
want_receipt=True)
"""
self.command = args.get('command')
self.headers = args.get('headers')
self.body = args.get('body')
if want_receipt:
receipt_stamp = str(random.randint(0, 10000000))
self.headers["receipt"] = "%s-%s" % (
self.session.get("session"), receipt_stamp)
return self
def as_string(self):
"""Raw string representation of this frame
Suitable for passing over a socket to the STOMP server.
Example
>>> stomp.send(frameobj.as_string())
"""
command = self.command
headers = self.headers
body = self.body
bytes_message = False
if 'bytes_message' in headers:
bytes_message = True
del headers['bytes_message']
headers['content-length'] = len(body)
headers['x-client'] = self.my_name
# Convert and append any existing headers to a string as the
# protocol describes.
headerparts = ("%s:%s\n" % (key, value)
for key, value in headers.iteritems())
# Frame is Command + Header + EOF marker.
frame = "%s\n%s\n%s\x00" % (command, "".join(headerparts), body)
return frame
def get_message(self, nb=False):
"""Get next message frame.
:keyword nb: Non-blocking: If this is set and there is no
messages currently waiting, this functions returns ``None``
instead of waiting for more data.
"""
while True:
frame = self.iqueue.get(self, nb=nb)
if not frame and nb:
return None
if frame.command == "MESSAGE":
return frame
else:
self.rqueue.put(frame)
def get_reply(self, nb=False):
"""Get command reply frame.
:keyword nb: Non-blocking: If this is set and there is no
messages currently waiting, this functions returns ``None``
instead of waiting for more data.
"""
while True:
try:
return self.rqueue.get_nowait()
except QueueEmpty:
frame = self.parse_frame(nb=nb)
if not frame and nb:
return None
if frame.command == "MESSAGE":
self.iqueue.put(frame)
else:
self.rqueue.put(frame)
def parse_frame(self, nb=False):
"""Parse data from socket
:keyword nb: Non-blocking: If this is set and there is no
messages currently waiting, this functions returns ``None``
instead of waiting for more data.
Example
>>> frameobj.parse_frame()
"""
line = self._getline(nb=nb)
if not line:
return
command = self.parse_command(line)
line = line[len(command)+1:]
headers_str, _, body = line.partition("\n\n")
if not headers_str:
raise UnknownBrokerResponseError(
"Received: (%s)" % line)
headers = self.parse_headers(headers_str)
if 'content-length' in headers:
headers['bytes_message'] = True
if command == 'ERROR':
raise BrokerErrorResponse(
"Broker Returned Error: %s" % body)
frame = Frame(self.sock)
return frame.build_frame({'command': command,
'headers': headers,
'body': body})
def parse_command(self, command_str):
"""Parse command received from the server.
:param command_str: String to parse command from
"""
command = command_str.split('\n', 1)[0]
return command
def parse_headers(self, headers_str):
"""Parse headers received from the servers and convert
to a :class:`dict`.i
:param headers_str: String to parse headers from
"""
# george:constanza\nelaine:benes
# -> {"george": "constanza", "elaine": "benes"}
return dict(line.split(":", 1) for line in headers_str.split("\n"))
def send_frame(self, frame):
"""Send frame to server, get receipt if needed.
:param frame: :class:`Frame` instance to pass across the socket
"""
self.sock.sendall(frame)
if 'receipt' in self.headers:
return self.get_reply()
def _getline(self, nb=False):
"""Get a single line from socket
:keyword nb: Non-blocking: If this is set, and there are no
messages to receive, this function returns ``None``.
"""
self.sock.setblocking(not nb)
try:
buffer = ''
partial = ''
while not buffer.endswith('\x00'):
try:
partial = self.sock.recv(1)
except socket.error, exc:
if exc[0] == EAGAIN:
if not buffer or buffer == '\n':
return None
continue
buffer += partial
finally:
self.sock.setblocking(nb)
# ** Nasty Alert **
# There may be a left over newline
# RabbitMQ doesn't have a newline after \x00
# ActiveMQ does. This is a hack around that.
# http://stomp.codehaus.org/Protocol mentions
# nothing about a newline following the NULL (^@)
if buffer[:1] == '\n':
return buffer[1:-1]
return buffer[:-1]
def __repr__(self):
return "<Frame %s>" % pformat(self.headers)
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