"""Dict-RPC servlets."""
import sys, traceback
from time import time
try:
from cPickle import dumps, PickleError
except ImportError:
from pickle import dumps, PickleError
try:
import zlib
except ImportError:
zlib = None
from RPCServlet import RPCServlet
from MiscUtils.PickleRPC import RequestError, SafeUnpickler
class PickleRPCServlet(RPCServlet, SafeUnpickler):
"""PickleRPCServlet is a base class for Dict-RPC servlets.
The "Pickle" refers to Python's pickle module. This class is
similar to XMLRPCServlet. By using Python pickles you get their
convenience (assuming the client is Pythonic), but lose
language independence. Some of us don't mind that last one. ;-)
Conveniences over XML-RPC include the use of all of the following:
* Any pickle-able Python type (datetime for example)
* Python instances (aka objects)
* None
* Longs that are outside the 32-bit int boundaries
* Keyword arguments
Pickles should also be faster than XML, especially now that
we support binary pickling and compression.
To make your own PickleRPCServlet, create a subclass and implement a
method which is then named in exposedMethods():
from WebKit.PickleRPCServlet import PickleRPCServlet
class Math(PickleRPCServlet):
def multiply(self, x, y):
return x * y
def exposedMethods(self):
return ['multiply']
To make a PickleRPC call from another Python program, do this:
from MiscUtils.PickleRPC import Server
server = Server('http://localhost/WebKit.cgi/Context/Math')
print server.multiply(3, 4) # 12
print server.multiply('-', 10) # ----------
If a request error is raised by the server, then
MiscUtils.PickleRPC.RequestError is raised. If an unhandled
exception is raised by the server, or the server response is
malformed, then MiscUtils.PickleRPC.ResponseError (or one of
its subclasses) is raised.
Tip: If you want callers of the RPC servlets to be able to
introspect what methods are available, then include
'exposedMethods' in exposedMethods().
If you wanted the actual response dictionary for some reason:
print server._request('multiply', 3, 4)
# {'value': 12, 'timeReceived': ...}
In which case, an exception is not purposefully raised if the
dictionary contains one. Instead, examine the dictionary.
For the dictionary formats and more information see the docs
for MiscUtils.PickleRPC.
"""
def respondToPost(self, trans):
try:
request = trans.request()
data = request.rawInput(rewind=1)
response = dict(timeReceived=trans.request().time())
try:
try:
encoding = request.environ().get('HTTP_CONTENT_ENCODING')
if encoding == 'x-gzip':
if zlib is not None:
try:
rawstring = data.read()
req = self.loads(zlib.decompress(rawstring))
except zlib.error:
raise RequestError(
'Cannot uncompress compressed dict-rpc request')
else:
raise RequestError(
'Cannot handle compressed dict-rpc request')
elif encoding:
raise RequestError(
'Cannot handle Content-Encoding of %s' % encoding)
else:
req = self.load(data)
except PickleError:
raise RequestError('Cannot unpickle dict-rpc request.')
if not isinstance(req, dict):
raise RequestError(
'Expecting a dictionary for dict-rpc requests, '
'but got %s instead.' % type(req))
if req.get('version', 1) != 1:
raise RequestError('Cannot handle version %s requests.'
% req['version'])
if req.get('action', 'call') != 'call':
raise RequestError(
'Cannot handle the request action, %r.' % req['action'])
try:
methodName = req['methodName']
except KeyError:
raise RequestError('Missing method in request')
args = req.get('args', ())
if methodName == '__methods__.__getitem__':
response['value'] = self.exposedMethods()[args[0]]
else:
response['value'] = self.call(methodName, *args,
**req.get('keywords', {}))
except RequestError, e:
response['requestError'] = str(e)
self.sendResponse(trans, response)
self.handleException(trans)
except Exception, e:
response['exception'] = self.resultForException(e, trans)
self.sendResponse(trans, response)
self.handleException(trans)
except:
response['exception'] = self.resultForException(
sys.exc_info()[0], trans)
self.sendResponse(trans, response)
self.handleException(trans)
else:
self.sendResponse(trans, response)
except Exception:
print 'PickleRPCServlet internal error'
print ''.join(traceback.format_exception(*sys.exc_info()))
trans.response().setStatus(500, 'Server Error')
self.handleException(trans)
def sendResponse(self, trans, response):
"""Timestamp the response dict and send it."""
response['timeResponded'] = time()
if self.useBinaryPickle():
contentType = 'application/x-python-binary-pickled-dict'
response = dumps(response, -1)
else:
contentType = 'text/x-python-pickled-dict'
response = dumps(response, 0)
try:
acceptEncoding = trans.request().environ()["HTTP_ACCEPT_ENCODING"]
if acceptEncoding:
acceptEncoding = [enc.strip()
for enc in acceptEncoding.split(',')]
else:
acceptEncoding = []
except KeyError:
acceptEncoding = []
if zlib is not None and 'gzip' in acceptEncoding and len(response) > 1000:
contentEncoding = 'x-gzip'
response = zlib.compress(response, 1)
else:
contentEncoding = None
self.sendOK(contentType, response, trans, contentEncoding)
@staticmethod
def useBinaryPickle():
"""Determine whether binary pickling format shall be used.
When this returns True, the highest available binary pickling format
will be used. Override this to return False to use the less-efficient
text pickling format.
"""
return True