88 lines
3.0 KiB
Python
88 lines
3.0 KiB
Python
#
|
|
# LMS Interface to external queueing system (xqueue)
|
|
#
|
|
import hashlib
|
|
import json
|
|
import requests
|
|
import time
|
|
|
|
# TODO: Collection of parameters to be hooked into rest of edX system
|
|
XQUEUE_LMS_AUTH = { 'username': 'LMS',
|
|
'password': 'PaloAltoCA' }
|
|
XQUEUE_SUBMIT_URL = 'http://xqueue.edx.org'
|
|
|
|
def make_hashkey(seed=None):
|
|
'''
|
|
Generate a string key by hashing
|
|
'''
|
|
h = hashlib.md5()
|
|
if seed is not None:
|
|
h.update(str(seed))
|
|
h.update(str(time.time()))
|
|
return h.hexdigest()
|
|
|
|
|
|
def make_xheader(lms_callback_url, lms_key, queue_name):
|
|
'''
|
|
Generate header for delivery and reply of queue request.
|
|
|
|
Xqueue header is a JSON-serialized dict:
|
|
{ 'lms_callback_url': url to which xqueue will return the request (string),
|
|
'lms_key': secret key used by LMS to protect its state (string),
|
|
'queue_name': designate a specific queue within xqueue server, e.g. 'MITx-6.00x' (string)
|
|
}
|
|
'''
|
|
return json.dumps({ 'lms_callback_url': lms_callback_url,
|
|
'lms_key': lms_key,
|
|
'queue_name': queue_name })
|
|
|
|
|
|
def send_to_queue(header, body, xqueue_url=None):
|
|
'''
|
|
Submit a request to xqueue.
|
|
|
|
header: JSON-serialized dict in the format described in 'xqueue_interface.make_xheader'
|
|
|
|
body: Serialized data for the receipient behind the queueing service. The operation of
|
|
xqueue is agnostic to the contents of 'body'
|
|
|
|
Returns an 'error' flag indicating error in xqueue transaction
|
|
'''
|
|
if xqueue_url is None:
|
|
xqueue_url = XQUEUE_SUBMIT_URL
|
|
|
|
# First, we login with our credentials
|
|
#------------------------------------------------------------
|
|
s = requests.session()
|
|
try:
|
|
r = s.post(xqueue_url+'/xqueue/login/', data={ 'username': XQUEUE_LMS_AUTH['username'],
|
|
'password': XQUEUE_LMS_AUTH['password'] })
|
|
except Exception as err:
|
|
msg = 'Error in xqueue_interface.send_to_queue %s: Cannot connect to server url=%s' % (err, xqueue_url)
|
|
raise Exception(msg)
|
|
|
|
# Xqueue responses are JSON-serialized dicts
|
|
xreply = json.loads(r.text)
|
|
return_code = xreply['return_code']
|
|
if return_code: # Nonzero return code from xqueue indicates error
|
|
print ' Error in queue_interface.send_to_queue: %s' % xreply['content']
|
|
return 1 # Error
|
|
|
|
# Next, we can make a queueing request
|
|
#------------------------------------------------------------
|
|
payload = {'xqueue_header': header,
|
|
'xqueue_body' : body}
|
|
try:
|
|
# Send request
|
|
r = s.post(xqueue_url+'/xqueue/submit/', data=payload)
|
|
except Exception as err:
|
|
msg = 'Error in xqueue_interface.send_to_queue %s: Cannot connect to server url=%s' % (err, xqueue_url)
|
|
raise Exception(msg)
|
|
|
|
xreply = json.loads(r.text)
|
|
return_code = xreply['return_code']
|
|
if return_code:
|
|
print ' Error in queue_interface.send_to_queue: %s' % xreply['content']
|
|
|
|
return return_code
|