jsonrpc.py

"""
Licensed under the Apache License, Version 2.0 (the "License"); 
you may not use this file except in compliance with the License. 
You may obtain a copy of the License at 

   http://www.apache.org/licenses/LICENSE-2.0 

Unless required by applicable law or agreed to in writing, software 
distributed under the License is distributed on an "AS IS" BASIS, 
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
See the License for the specific language governing permissions and 
limitations under the License. 

============================
JSONRPC Library (jsonrpclib)
============================

This library is a JSON-RPC v.2 (proposed) implementation which
follows the xmlrpclib API for portability between clients. It
uses the same Server / ServerProxy, loads, dumps, etc. syntax,
while providing features not present in XML-RPC like:

* Keyword arguments
* Notifications
* Versioning
* Batches and batch notifications

Eventually, I'll add a SimpleXMLRPCServer compatible library,
and other things to tie the thing off nicely. :)

For a quick-start, just open a console and type the following,
replacing the server address, method, and parameters 
appropriately.
>>> import jsonrpclib
>>> server = jsonrpclib.Server('http://localhost:8181')
>>> server.add(5, 6)
11
>>> server._notify.add(5, 6)
>>> batch = jsonrpclib.MultiCall(server)
>>> batch.add(3, 50)
>>> batch.add(2, 3)
>>> batch._notify.add(3, 5)
>>> batch()
[53, 5]

See http://code.google.com/p/jsonrpclib/ for more info.
"""

import types
import sys
from xmlrpclib import Transport as XMLTransport
from xmlrpclib import SafeTransport as XMLSafeTransport
from xmlrpclib import ServerProxy as XMLServerProxy
from xmlrpclib import _Method as XML_Method
import time
import string
import random

# Library includes
import jsonrpclib
from jsonrpclib import config
from jsonrpclib import history

# JSON library importing
cjson = None
json = None
try:
    import cjson
except ImportError:
    try:
        import json
    except ImportError:
        try:
            import simplejson as json
        except ImportError:
            raise ImportError(
                'You must have the cjson, json, or simplejson ' +
                'module(s) available.'
            )

IDCHARS = string.ascii_lowercase+string.digits

class UnixSocketMissing(Exception):
    """ 
    Just a properly named Exception if Unix Sockets usage is 
    attempted on a platform that doesn't support them (Windows)
    """
    pass

#JSON Abstractions

def jdumps(obj, encoding='utf-8'):
    # Do 'serialize' test at some point for other classes
    global cjson
    if cjson:
        return cjson.encode(obj)
    else:
        return json.dumps(obj, encoding=encoding)

def jloads(json_string):
    global cjson
    if cjson:
        return cjson.decode(json_string)
    else:
        return json.loads(json_string)


# XMLRPClib re-implementations

class ProtocolError(Exception):
    pass

class TransportMixIn(object):
    """ Just extends the XMLRPC transport where necessary. """
    user_agent = config.user_agent
    # for Python 2.7 support
    _connection = None

    def send_content(self, connection, request_body):
        connection.putheader("Content-Type", "application/json-rpc")
        connection.putheader("Content-Length", str(len(request_body)))
        connection.endheaders()
        if request_body:
            connection.send(request_body)

    def getparser(self):
        target = JSONTarget()
        return JSONParser(target), target

class JSONParser(object):
    def __init__(self, target):
        self.target = target

    def feed(self, data):
        self.target.feed(data)

    def close(self):
        pass

class JSONTarget(object):
    def __init__(self):
        self.data = []

    def feed(self, data):
        self.data.append(data)

    def close(self):
        return ''.join(self.data)

class Transport(TransportMixIn, XMLTransport):
    pass

class SafeTransport(TransportMixIn, XMLSafeTransport):
    pass
from httplib import HTTP, HTTPConnection
from socket import socket

USE_UNIX_SOCKETS = False

try: 
    from socket import AF_UNIX, SOCK_STREAM
    USE_UNIX_SOCKETS = True
except ImportError:
    pass
    
if (USE_UNIX_SOCKETS):
    
    class UnixHTTPConnection(HTTPConnection):
        def connect(self):
            self.sock = socket(AF_UNIX, SOCK_STREAM)
            self.sock.connect(self.host)

    class UnixHTTP(HTTP):
        _connection_class = UnixHTTPConnection

    class UnixTransport(TransportMixIn, XMLTransport):
        def make_connection(self, host):
            import httplib
            host, extra_headers, x509 = self.get_host_info(host)
            return UnixHTTP(host)

    
class ServerProxy(XMLServerProxy):
    """
    Unfortunately, much more of this class has to be copied since
    so much of it does the serialization.
    """

    def __init__(self, uri, transport=None, encoding=None, 
                 verbose=0, version=None):
        import urllib
        if not version:
            version = config.version
        self.__version = version
        schema, uri = urllib.splittype(uri)
        if schema not in ('http', 'https', 'unix'):
            raise IOError('Unsupported JSON-RPC protocol.')
        if schema == 'unix':
            if not USE_UNIX_SOCKETS:
                # Don't like the "generic" Exception...
                raise UnixSocketMissing("Unix sockets not available.")
            self.__host = uri
            self.__handler = '/'
        else:
            self.__host, self.__handler = urllib.splithost(uri)
            if not self.__handler:
                # Not sure if this is in the JSON spec?
                #self.__handler = '/'
                self.__handler == '/'
        if transport is None:
            if schema == 'unix':
                transport = UnixTransport()
            elif schema == 'https':
                transport = SafeTransport()
            else:
                transport = Transport()
        self.__transport = transport
        self.__encoding = encoding
        self.__verbose = verbose

    def _request(self, methodname, params, rpcid=None):
        request = dumps(params, methodname, encoding=self.__encoding,
                        rpcid=rpcid, version=self.__version)
        response = self._run_request(request)
        check_for_errors(response)
        return response['result']

    def _request_notify(self, methodname, params, rpcid=None):
        request = dumps(params, methodname, encoding=self.__encoding,
                        rpcid=rpcid, version=self.__version, notify=True)
        response = self._run_request(request, notify=True)
        check_for_errors(response)
        return

    def _run_request(self, request, notify=None):
        history.add_request(request)

        response = self.__transport.request(
            self.__host,
            self.__handler,
            request,
            verbose=self.__verbose
        )
        
        # Here, the XMLRPC library translates a single list
        # response to the single value -- should we do the
        # same, and require a tuple / list to be passed to
        # the response object, or expect the Server to be 
        # outputting the response appropriately?
        
        history.add_response(response)
        if not response:
            return None
        return_obj = loads(response)
        return return_obj

    def __getattr__(self, name):
        # Same as original, just with new _Method reference
        return _Method(self._request, name)

    @property
    def _notify(self):
        # Just like __getattr__, but with notify namespace.
        return _Notify(self._request_notify)


class _Method(XML_Method):
    
    def __call__(self, *args, **kwargs):
        if len(args) > 0 and len(kwargs) > 0:
            raise ProtocolError('Cannot use both positional ' +
                'and keyword arguments (according to JSON-RPC spec.)')
        if len(args) > 0:
            return self.__send(self.__name, args)
        else:
            return self.__send(self.__name, kwargs)

    def __getattr__(self, name):
        self.__name = '%s.%s' % (self.__name, name)
        return self
        # The old method returned a new instance, but this seemed wasteful.
        # The only thing that changes is the name.
        #return _Method(self.__send, "%s.%s" % (self.__name, name))

class _Notify(object):
    def __init__(self, request):
        self._request = request

    def __getattr__(self, name):
        return _Method(self._request, name)
        
# Batch implementation

class MultiCallMethod(object):
    
    def __init__(self, method, notify=False):
        self.method = method
        self.params = []
        self.notify = notify

    def __call__(self, *args, **kwargs):
        if len(kwargs) > 0 and len(args) > 0:
            raise ProtocolError('JSON-RPC does not support both ' +
                                'positional and keyword arguments.')
        if len(kwargs) > 0:
            self.params = kwargs
        else:
            self.params = args

    def request(self, encoding=None, rpcid=None):
        return dumps(self.params, self.method, version=2.0,
                     encoding=encoding, rpcid=rpcid, notify=self.notify)

    def __repr__(self):
        return '%s' % self.request()
        
    def __getattr__(self, method):
        new_method = '%s.%s' % (self.method, method)
        self.method = new_method
        return self

class MultiCallNotify(object):
    
    def __init__(self, multicall):
        self.multicall = multicall

    def __getattr__(self, name):
        new_job = MultiCallMethod(name, notify=True)
        self.multicall._job_list.append(new_job)
        return new_job

class MultiCallIterator(object):
    
    def __init__(self, results):
        self.results = results

    def __iter__(self):
        for i in range(0, len(self.results)):
            yield self[i]
        raise StopIteration

    def __getitem__(self, i):
        item = self.results[i]
        check_for_errors(item)
        return item['result']

    def __len__(self):
        return len(self.results)

class MultiCall(object):
    
    def __init__(self, server):
        self._server = server
        self._job_list = []

    def _request(self):
        if len(self._job_list) < 1:
            # Should we alert? This /is/ pretty obvious.
            return
        request_body = '[ %s ]' % ','.join([job.request() for
                                          job in self._job_list])
        responses = self._server._run_request(request_body)
        del self._job_list[:]
        if not responses:
            responses = []
        return MultiCallIterator(responses)

    @property
    def _notify(self):
        return MultiCallNotify(self)

    def __getattr__(self, name):
        new_job = MultiCallMethod(name)
        self._job_list.append(new_job)
        return new_job

    __call__ = _request

# These lines conform to xmlrpclib's "compatibility" line. 
# Not really sure if we should include these, but oh well.
Server = ServerProxy

class Fault(object):
    # JSON-RPC error class
    def __init__(self, code=-32000, message='Server error', rpcid=None):
        self.faultCode = code
        self.faultString = message
        self.rpcid = rpcid

    def error(self):
        return {'code':self.faultCode, 'message':self.faultString}

    def response(self, rpcid=None, version=None):
        if not version:
            version = config.version
        if rpcid:
            self.rpcid = rpcid
        return dumps(
            self, methodresponse=True, rpcid=self.rpcid, version=version
        )

    def __repr__(self):
        return '<Fault %s: %s>' % (self.faultCode, self.faultString)

def random_id(length=8):
    return_id = ''
    for i in range(length):
        return_id += random.choice(IDCHARS)
    return return_id

class Payload(dict):
    def __init__(self, rpcid=None, version=None):
        if not version:
            version = config.version
        self.id = rpcid
        self.version = float(version)
    
    def request(self, method, params=[]):
        if type(method) not in types.StringTypes:
            raise ValueError('Method name must be a string.')
        if not self.id:
            self.id = random_id()
        request = { 'id':self.id, 'method':method }
        if params:
            request['params'] = params
        if self.version >= 2:
            request['jsonrpc'] = str(self.version)
        return request

    def notify(self, method, params=[]):
        request = self.request(method, params)
        if self.version >= 2:
            del request['id']
        else:
            request['id'] = None
        return request

    def response(self, result=None):
        response = {'result':result, 'id':self.id}
        if self.version >= 2:
            response['jsonrpc'] = str(self.version)
        else:
            response['error'] = None
        return response

    def error(self, code=-32000, message='Server error.'):
        error = self.response()
        if self.version >= 2:
            del error['result']
        else:
            error['result'] = None
        error['error'] = {'code':code, 'message':message}
        return error

def dumps(params=[], methodname=None, methodresponse=None, 
        encoding=None, rpcid=None, version=None, notify=None):
    """
    This differs from the Python implementation in that it implements 
    the rpcid argument since the 2.0 spec requires it for responses.
    """
    if not version:
        version = config.version
    valid_params = (types.TupleType, types.ListType, types.DictType)
    if methodname in types.StringTypes and \
            type(params) not in valid_params and \
            not isinstance(params, Fault):
        """ 
        If a method, and params are not in a listish or a Fault,
        error out.
        """
        raise TypeError('Params must be a dict, list, tuple or Fault ' +
                        'instance.')
    # Begin parsing object
    payload = Payload(rpcid=rpcid, version=version)
    if not encoding:
        encoding = 'utf-8'
    if type(params) is Fault:
        response = payload.error(params.faultCode, params.faultString)
        return jdumps(response, encoding=encoding)
    if type(methodname) not in types.StringTypes and methodresponse != True:
        raise ValueError('Method name must be a string, or methodresponse '+
                         'must be set to True.')
    if config.use_jsonclass == True:
        from jsonrpclib import jsonclass
        params = jsonclass.dump(params)
    if methodresponse is True:
        if rpcid is None:
            raise ValueError('A method response must have an rpcid.')
        response = payload.response(params)
        return jdumps(response, encoding=encoding)
    request = None
    if notify == True:
        request = payload.notify(methodname, params)
    else:
        request = payload.request(methodname, params)
    return jdumps(request, encoding=encoding)

def loads(data):
    """
    This differs from the Python implementation, in that it returns
    the request structure in Dict format instead of the method, params.
    It will return a list in the case of a batch request / response.
    """
    if data == '':
        # notification
        return None
    result = jloads(data)
    # if the above raises an error, the implementing server code 
    # should return something like the following:
    # { 'jsonrpc':'2.0', 'error': fault.error(), id: None }
    if config.use_jsonclass == True:
        from jsonrpclib import jsonclass
        result = jsonclass.load(result)
    return result

def check_for_errors(result):
    if not result:
        # Notification
        return result
    if type(result) is not types.DictType:
        raise TypeError('Response is not a dict.')
    if 'jsonrpc' in result.keys() and float(result['jsonrpc']) > 2.0:
        raise NotImplementedError('JSON-RPC version not yet supported.')
    if 'result' not in result.keys() and 'error' not in result.keys():
        raise ValueError('Response does not have a result or error key.')
    if 'error' in result.keys() and result['error'] != None:
        code = result['error']['code']
        message = result['error']['message']
        raise ProtocolError((code, message))
    return result

def isbatch(result):
    if type(result) not in (types.ListType, types.TupleType):
        return False
    if len(result) < 1:
        return False
    if type(result[0]) is not types.DictType:
        return False
    if 'jsonrpc' not in result[0].keys():
        return False
    try:
        version = float(result[0]['jsonrpc'])
    except ValueError:
        raise ProtocolError('"jsonrpc" key must be a float(able) value.')
    if version < 2:
        return False
    return True

def isnotification(request):
    if 'id' not in request.keys():
        # 2.0 notification
        return True
    if request['id'] == None:
        # 1.0 notification
        return True
    return False