Lib/xmlrpclib.py

#
# XML-RPC CLIENT LIBRARY
# $Id$
#
# History:
# 1999-01-14 fl  Created
# 1999-01-15 fl  Changed dateTime to use localtime
# 1999-01-16 fl  Added Binary/base64 element, default to RPC2 service
# 1999-01-19 fl  Fixed array data element (from Skip Montanaro)
# 1999-01-21 fl  Fixed dateTime constructor, etc.
# 1999-02-02 fl  Added fault handling, handle empty sequences, etc.
# 1999-02-10 fl  Fixed problem with empty responses (from Skip Montanaro)
# 1999-06-20 fl  Speed improvements, pluggable parsers/transports (0.9.8)
# 2000-11-28 fl  Changed boolean to check the truth value of its argument
# 2001-02-24 fl  Added encoding/Unicode/SafeTransport patches
# 2001-02-26 fl  Added compare support to wrappers (0.9.9/1.0b1)
# 2001-03-28 fl  Make sure response tuple is a singleton
# 2001-03-29 fl  Don't require empty params element (from Nicholas Riley)
# 2001-06-10 fl  Folded in _xmlrpclib accelerator support (1.0b2)
# 2001-08-20 fl  Base xmlrpclib.Error on built-in Exception (from Paul Prescod)
#
# Copyright (c) 1999-2001 by Secret Labs AB.
# Copyright (c) 1999-2001 by Fredrik Lundh.
#
# info@pythonware.com
# http://www.pythonware.com
#
# --------------------------------------------------------------------
# The XML-RPC client interface is
#
# Copyright (c) 1999-2001 by Secret Labs AB
# Copyright (c) 1999-2001 by Fredrik Lundh
#
# By obtaining, using, and/or copying this software and/or its
# associated documentation, you agree that you have read, understood,
# and will comply with the following terms and conditions:
#
# Permission to use, copy, modify, and distribute this software and
# its associated documentation for any purpose and without fee is
# hereby granted, provided that the above copyright notice appears in
# all copies, and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of
# Secret Labs AB or the author not be used in advertising or publicity
# pertaining to distribution of the software without specific, written
# prior permission.
#
# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
# ABILITY AND FITNESS.  IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
# OF THIS SOFTWARE.
# --------------------------------------------------------------------

#
# things to look into before 1.0 final:

# TODO: unicode marshalling -DONE
# TODO: ascii-compatible encoding support -DONE
# TODO: safe transport -DONE (but mostly untested)
# TODO: sgmlop memory leak -DONE
# TODO: sgmlop xml parsing -DONE
# TODO: support unicode method names -DONE
# TODO: update selftest -DONE
# TODO: add docstrings -DONE
# TODO: clean up parser encoding (trust the parser) -DONE
# TODO: expat support -DONE
# TODO: _xmlrpclib accelerator support -DONE
# TODO: use smarter/faster escape from effdom
# TODO: support basic authentication (see robin's patch)
# TODO: fix host tuple handling in the server constructor
# TODO: let transport verify schemes
# TODO: update documentation
# TODO: authentication plugins
# TODO: memo problem (see HP's mail)

"""
An XML-RPC client interface for Python.

The marshalling and response parser code can also be used to
implement XML-RPC servers.

Notes:
This version is designed to work with Python 1.5.2 or newer.
Unicode encoding support requires at least Python 1.6.
Experimental HTTPS requires Python 2.0 built with SSL sockets.
Expat parser support requires Python 2.0 with pyexpat support.

Exported exceptions:

    Error          Base class for client errors
    ProtocolError  Indicates an HTTP protocol error
    ResponseError  Indicates a broken response package
    Fault          Indicates a XML-RPC fault package

Exported classes:

    Boolean        boolean wrapper to generate a "boolean" XML-RPC value
    DateTime       dateTime wrapper for an ISO 8601 string or time tuple or
                   localtime integer value to generate a "dateTime.iso8601"
                   XML-RPC value
    Binary         binary data wrapper

    SlowParser     Slow but safe standard parser
    Marshaller     Generate an XML-RPC params chunk from a Python data structure
    Unmarshaller   Unmarshal an XML-RPC response from incoming XML event message

    Transport      Handles an HTTP transaction to an XML-RPC server
    SafeTransport  Handles an HTTPS transaction to an XML-RPC server
    ServerProxy    Connect to a server through a proxy
    Server         Same as ServerProxy

Exported constants:

    True
    False

Exported functions:

    boolean        Convert any Python value to an XML-RPC boolean
    datetime       Convert value to an XML-RPC datetime
    binary         Convert value to an XML-RPC binary value
    getparser      Create instance of the fastest available parser & attach
                   to an unmarshalling object
    dumps          Convert an argument tuple or a Fault instance to an XML-RPC
                   request (or response, if the methodresponse option is used).
    loads          Convert an XML-RPC packet to unmarshalled data plus a method
                   name (None if not present).

"""

import re, string, time, operator
import urllib, xmllib
from types import *
from cgi import escape

try:
    unicode
except NameError:
    unicode = None # unicode support not available

def _decode(data, encoding, is8bit=re.compile("[\x80-\xff]").search):
    # decode non-ascii string (if possible)
    if unicode and encoding and is8bit(data):
        data = unicode(data, encoding)
    return data

if unicode:
    def _stringify(string):
        # convert to 7-bit ascii if possible
        try:
            return str(string)
        except UnicodeError:
            return string
else:
    def _stringify(string):
        return string

__version__ = "1.0b3"

# --------------------------------------------------------------------
# Exceptions

class Error(Exception):
    """Base class for client errors."""
    pass

class ProtocolError(Error):
    """Indicates an HTTP protocol error."""
    def __init__(self, url, errcode, errmsg, headers):
        self.url = url
        self.errcode = errcode
        self.errmsg = errmsg
        self.headers = headers
    def __repr__(self):
        return (
            "<ProtocolError for %s: %s %s>" %
            (self.url, self.errcode, self.errmsg)
            )

class ResponseError(Error):
    """Indicates a broken response package"""
    pass

class Fault(Error):
    """indicates a XML-RPC fault package"""
    def __init__(self, faultCode, faultString, **extra):
        self.faultCode = faultCode
        self.faultString = faultString
    def __repr__(self):
        return (
            "<Fault %s: %s>" %
            (self.faultCode, repr(self.faultString))
            )

# --------------------------------------------------------------------
# Special values


class Boolean:
    """Boolean-value wrapper.

    Use True or False to generate a "boolean" XML-RPC value.
    """

    def __init__(self, value = 0):
        self.value = operator.truth(value)

    def encode(self, out):
        out.write("<value><boolean>%d</boolean></value>\n" % self.value)

    def __cmp__(self, other):
        if isinstance(other, Boolean):
            other = other.value
        return cmp(self.value, other)

    def __repr__(self):
        if self.value:
            return "<Boolean True at %x>" % id(self)
        else:
            return "<Boolean False at %x>" % id(self)

    def __int__(self):
        return self.value

    def __nonzero__(self):
        return self.value

True, False = Boolean(1), Boolean(0)

def boolean(value, truefalse=(False, True)):
    """Convert any Python value to XML-RPC boolean."""
    return truefalse[operator.truth(value)]

#
# dateTime wrapper
# wrap your iso8601 string or time tuple or localtime integer value
# in this class to generate a "dateTime.iso8601" XML-RPC value

class DateTime:
    """DataTime wrapper for an ISO 8601 string or time tuple or
    localtime integer value to generate a 'dateTime.iso8601' XML-RPC
    value."""

    def __init__(self, value=0):
        if not isinstance(value, StringType):
            if not isinstance(value, TupleType):
                if value == 0:
                    value = time.time()
                value = time.localtime(value)
            value = time.strftime("%Y%m%dT%H:%M:%S", value)
        self.value = value

    def __cmp__(self, other):
        if isinstance(other, DateTime):
            other = other.value
        return cmp(self.value, other)

    def __repr__(self):
        return "<DateTime %s at %x>" % (self.value, id(self))

    def decode(self, data):
        self.value = string.strip(data)

    def encode(self, out):
        out.write("<value><dateTime.iso8601>")
        out.write(self.value)
        out.write("</dateTime.iso8601></value>\n")

def datetime(data):
    value = DateTime()
    value.decode(data)
    return value


class Binary:
    """Wrapper for binary data."""

    def __init__(self, data=None):
        self.data = data

    def __cmp__(self, other):
        if isinstance(other, Binary):
            other = other.data
        return cmp(self.data, other)

    def decode(self, data):
        import base64
        self.data = base64.decodestring(data)

    def encode(self, out):
        import base64, StringIO
        out.write("<value><base64>\n")
        base64.encode(StringIO.StringIO(self.data), out)
        out.write("</base64></value>\n")

def binary(data):
    value = Binary()
    value.decode(data)
    return value

WRAPPERS = DateTime, Binary, Boolean

# --------------------------------------------------------------------
# XML parsers

try:
    # optional xmlrpclib accelerator.  for more information on this
    # component, contact info@pythonware.com
    import _xmlrpclib
    FastParser = _xmlrpclib.Parser
    FastUnmarshaller = _xmlrpclib.Unmarshaller
except (AttributeError, ImportError):
    FastParser = FastUnmarshaller = None

#
# the SGMLOP parser is about 15x faster than Python's builtin
# XML parser.  SGMLOP sources can be downloaded from:
#
#     http://www.pythonware.com/products/xml/sgmlop.htm
#

try:
    import sgmlop
    if not hasattr(sgmlop, "XMLParser"):
        raise ImportError
except ImportError:
    SgmlopParser = None # sgmlop accelerator not available
else:
    class SgmlopParser:
        def __init__(self, target):

            # setup callbacks
            self.finish_starttag = target.start
            self.finish_endtag = target.end
            self.handle_data = target.data
            self.handle_xml = target.xml

            # activate parser
            self.parser = sgmlop.XMLParser()
            self.parser.register(self)
            self.feed = self.parser.feed
            self.entity = {
                "amp": "&", "gt": ">", "lt": "<",
                "apos": "'", "quot": '"'
                }

        def close(self):
            try:
                self.parser.close()
            finally:
                self.parser = self.feed = None # nuke circular reference

        def handle_proc(self, tag, attr):
            m = re.search("encoding\s*=\s*['\"]([^\"']+)[\"']", attr)
            if m:
                self.handle_xml(m.group(1), 1)

        def handle_entityref(self, entity):
            # <string> entity
            try:
                self.handle_data(self.entity[entity])
            except KeyError:
                self.handle_data("&%s;" % entity)

try:
    from xml.parsers import expat
except ImportError:
    ExpatParser = None
else:
    class ExpatParser:
        # fast expat parser for Python 2.0.  this is about 50%
        # slower than sgmlop, on roundtrip testing
        def __init__(self, target):
            self._parser = parser = expat.ParserCreate(None, None)
            self._target = target
            parser.StartElementHandler = target.start
            parser.EndElementHandler = target.end
            parser.CharacterDataHandler = target.data
            encoding = None
            if not parser.returns_unicode:
                encoding = "utf-8"
            target.xml(encoding, None)

        def feed(self, data):
            self._parser.Parse(data, 0)

        def close(self):
            self._parser.Parse("", 1) # end of data
            del self._target, self._parser # get rid of circular references

class SlowParser(xmllib.XMLParser):
    """XML parser using xmllib.XMLParser.

    This is about 10 times slower than sgmlop on roundtrip testing.
    """

    def __init__(self, target):
        self.handle_xml = target.xml
        self.unknown_starttag = target.start
        self.handle_data = target.data
        self.unknown_endtag = target.end
        xmllib.XMLParser.__init__(self)


# --------------------------------------------------------------------
# XML-RPC marshalling and unmarshalling code

class Marshaller:
    """Generate an XML-RPC params chunk from a Python data structure.

    Create a marshaller instance for each set of parameters, and use
    "dumps" method to convert your data (represented as a tuple) to a
    XML-RPC params chunk.  to write a fault response, pass a Fault
    instance instead.  You may prefer to use the "dumps" convenience
    function for this purpose (see below).
    """

    # by the way, if you don't understand what's going on in here,
    # that's perfectly ok.

    def __init__(self, encoding=None):
        self.memo = {}
        self.data = None
        self.encoding = encoding

    dispatch = {}

    def dumps(self, values):
        self.__out = []
        self.write = write = self.__out.append
        if isinstance(values, Fault):
            # fault instance
            write("<fault>\n")
            self.__dump(vars(values))
            write("</fault>\n")
        else:
            # parameter block
            # FIXME: the xml-rpc specification allows us to leave out
            # the entire <params> block if there are no parameters.
            # however, changing this may break older code (including
            # old versions of xmlrpclib.py), so this is better left as
            # is for now.  See @XMLRPC3 for more information. /F
            write("<params>\n")
            for v in values:
                write("<param>\n")
                self.__dump(v)
                write("</param>\n")
            write("</params>\n")
        result = string.join(self.__out, "")
        del self.__out, self.write # don't need this any more
        return result

    def __dump(self, value):
        try:
            f = self.dispatch[type(value)]
        except KeyError:
            raise TypeError, "cannot marshal %s objects" % type(value)
        else:
            f(self, value)

    def dump_int(self, value):
        self.write("<value><int>%s</int></value>\n" % value)
    dispatch[IntType] = dump_int

    def dump_double(self, value):
        self.write("<value><double>%s</double></value>\n" % value)
    dispatch[FloatType] = dump_double

    def dump_string(self, value):
        self.write("<value><string>%s</string></value>\n" % escape(value))
    dispatch[StringType] = dump_string

    if unicode:
        def dump_unicode(self, value):
            value = value.encode(self.encoding)
            self.write("<value><string>%s</string></value>\n" % escape(value))
        dispatch[UnicodeType] = dump_unicode

    def container(self, value):
        if value:
            i = id(value)
            if self.memo.has_key(i):
                raise TypeError, "cannot marshal recursive data structures"
            self.memo[i] = None

    def dump_array(self, value):
        self.container(value)
        write = self.write
        write("<value><array><data>\n")
        for v in value:
            self.__dump(v)
        write("</data></array></value>\n")
    dispatch[TupleType] = dump_array
    dispatch[ListType] = dump_array

    def dump_struct(self, value):
        self.container(value)
        write = self.write
        write("<value><struct>\n")
        for k, v in value.items():
            write("<member>\n")
            if type(k) is not StringType:
                raise TypeError, "dictionary key must be string"
            write("<name>%s</name>\n" % escape(k))
            self.__dump(v)
            write("</member>\n")
        write("</struct></value>\n")
    dispatch[DictType] = dump_struct

    def dump_instance(self, value):
        # check for special wrappers
        if value.__class__ in WRAPPERS:
            value.encode(self)
        else:
            # store instance attributes as a struct (really?)
            self.dump_struct(value.__dict__)
    dispatch[InstanceType] = dump_instance

class Unmarshaller:
    """Unmarshal an XML-RPC response, based on incoming XML event
    messages (start, data, end).  Call close() to get the resulting
    data structure.

    Note that this reader is fairly tolerant, and gladly accepts
    bogus XML-RPC data without complaining (but not bogus XML).
    """

    # and again, if you don't understand what's going on in here,
    # that's perfectly ok.

    def __init__(self):
        self._type = None
        self._stack = []
        self._marks = []
        self._data = []
        self._methodname = None
        self._encoding = "utf-8"
        self.append = self._stack.append

    def close(self):
        # return response tuple and target method
        if self._type is None or self._marks:
            raise ResponseError()
        if self._type == "fault":
            raise apply(Fault, (), self._stack[0])
        return tuple(self._stack)

    def getmethodname(self):
        return self._methodname

    #
    # event handlers

    def xml(self, encoding, standalone):
        self._encoding = encoding
        # FIXME: assert standalone == 1 ???

    def start(self, tag, attrs):
        # prepare to handle this element
        if tag == "array" or tag == "struct":
            self._marks.append(len(self._stack))
        self._data = []
        self._value = (tag == "value")

    def data(self, text):
        self._data.append(text)

    def end(self, tag):
        # call the appropriate end tag handler
        try:
            f = self.dispatch[tag]
        except KeyError:
            pass # unknown tag ?
        else:
            return f(self, self._data)

    #
    # accelerator support

    def end_dispatch(self, tag, data):
        # dispatch data
        try:
            f = self.dispatch[tag]
        except KeyError:
            pass # unknown tag ?
        else:
            return f(self, data)

    #
    # element decoders

    dispatch = {}

    def end_boolean(self, data, join=string.join):
        data = join(data, "")
        if data == "0":
            self.append(False)
        elif data == "1":
            self.append(True)
        else:
            raise TypeError, "bad boolean value"
        self._value = 0
    dispatch["boolean"] = end_boolean

    def end_int(self, data, join=string.join):
        self.append(int(join(data, "")))
        self._value = 0
    dispatch["i4"] = end_int
    dispatch["int"] = end_int

    def end_double(self, data, join=string.join):
        self.append(float(join(data, "")))
        self._value = 0
    dispatch["double"] = end_double

    def end_string(self, data, join=string.join):
        data = join(data, "")
        if self._encoding:
            data = _decode(data, self._encoding)
        self.append(_stringify(data))
        self._value = 0
    dispatch["string"] = end_string
    dispatch["name"] = end_string # struct keys are always strings

    def end_array(self, data):
        mark = self._marks[-1]
        del self._marks[-1]
        # map arrays to Python lists
        self._stack[mark:] = [self._stack[mark:]]
        self._value = 0
    dispatch["array"] = end_array

    def end_struct(self, data):
        mark = self._marks[-1]
        del self._marks[-1]
        # map structs to Python dictionaries
        dict = {}
        items = self._stack[mark:]
        for i in range(0, len(items), 2):
            dict[_stringify(items[i])] = items[i+1]
        self._stack[mark:] = [dict]
        self._value = 0
    dispatch["struct"] = end_struct

    def end_base64(self, data, join=string.join):
        value = Binary()
        value.decode(join(data, ""))
        self.append(value)
        self._value = 0
    dispatch["base64"] = end_base64

    def end_dateTime(self, data, join=string.join):
        value = DateTime()
        value.decode(join(data, ""))
        self.append(value)
    dispatch["dateTime.iso8601"] = end_dateTime

    def end_value(self, data):
        # if we stumble upon an value element with no internal
        # elements, treat it as a string element
        if self._value:
            self.end_string(data)
    dispatch["value"] = end_value

    def end_params(self, data):
        self._type = "params"
    dispatch["params"] = end_params

    def end_fault(self, data):
        self._type = "fault"
    dispatch["fault"] = end_fault

    def end_methodName(self, data, join=string.join):
        data = join(data, "")
        if self._encoding:
            data = _decode(data, self._encoding)
        self._methodname = data
        self._type = "methodName" # no params
    dispatch["methodName"] = end_methodName


# --------------------------------------------------------------------
# convenience functions

def getparser():
    """getparser() -> parser, unmarshaller

    Create an instance of the fastest available parser, and attach
    it to an unmarshalling object.  Return both objects.
    """
    if FastParser and FastUnmarshaller:
        target = FastUnmarshaller(True, False, binary, datetime)
        parser = FastParser(target)
    else:
        target = Unmarshaller()
        if FastParser:
            parser = FastParser(target)
        elif SgmlopParser:
            parser = SgmlopParser(target)
        elif ExpatParser:
            parser = ExpatParser(target)
        else:
            parser = SlowParser(target)
    return parser, target

def dumps(params, methodname=None, methodresponse=None, encoding=None):
    """data [,options] -> marshalled data

    Convert an argument tuple or a Fault instance to an XML-RPC
    request (or response, if the methodresponse option is used).

    In addition to the data object, the following options can be
    given as keyword arguments:

        methodname: the method name for a methodCall packet

        methodresponse: true to create a methodResponse packet.
        If this option is used with a tuple, the tuple must be
        a singleton (i.e. it can contain only one element).

        encoding: the packet encoding (default is UTF-8)

    All 8-bit strings in the data structure are assumed to use the
    packet encoding.  Unicode strings are automatically converted,
    as necessary.
    """

    assert isinstance(params, TupleType) or isinstance(params, Fault),\
           "argument must be tuple or Fault instance"

    if isinstance(params, Fault):
        methodresponse = 1
    elif methodresponse and isinstance(params, TupleType):
        assert len(params) == 1, "response tuple must be a singleton"

    if not encoding:
        encoding = "utf-8"

    m = Marshaller(encoding)
    data = m.dumps(params)

    if encoding != "utf-8":
        xmlheader = "<?xml version='1.0' encoding=%s?>\n" % repr(encoding)
    else:
        xmlheader = "<?xml version='1.0'?>\n" # utf-8 is default

    # standard XML-RPC wrappings
    if methodname:
        # a method call
        if not isinstance(methodname, StringType):
            methodname = methodname.encode(encoding)
        data = (
            xmlheader,
            "<methodCall>\n"
            "<methodName>", methodname, "</methodName>\n",
            data,
            "</methodCall>\n"
            )
    elif methodresponse:
        # a method response, or a fault structure
        data = (
            xmlheader,
            "<methodResponse>\n",
            data,
            "</methodResponse>\n"
            )
    else:
        return data # return as is
    return string.join(data, "")

def loads(data):
    """data -> unmarshalled data, method name

    Convert an XML-RPC packet to unmarshalled data plus a method
    name (None if not present).

    If the XML-RPC packet represents a fault condition, this function
    raises a Fault exception.
    """
    p, u = getparser()
    p.feed(data)
    p.close()
    return u.close(), u.getmethodname()


# --------------------------------------------------------------------
# request dispatcher

class _Method:
    # some magic to bind an XML-RPC method to an RPC server.
    # supports "nested" methods (e.g. examples.getStateName)
    def __init__(self, send, name):
        self.__send = send
        self.__name = name
    def __getattr__(self, name):
        return _Method(self.__send, "%s.%s" % (self.__name, name))
    def __call__(self, *args):
        return self.__send(self.__name, args)


class Transport:
    """Handles an HTTP transaction to an XML-RPC server"""

    # client identifier (may be overridden)
    user_agent = "xmlrpclib.py/%s (by www.pythonware.com)" % __version__

    def request(self, host, handler, request_body, verbose=0):
        # issue XML-RPC request

        h = self.make_connection(host)
        if verbose:
            h.set_debuglevel(1)

        self.send_request(h, handler, request_body)
        self.send_host(h, host)
        self.send_user_agent(h)
        self.send_content(h, request_body)

        errcode, errmsg, headers = h.getreply()

        if errcode != 200:
            raise ProtocolError(
                host + handler,
                errcode, errmsg,
                headers
                )

        self.verbose = verbose

        return self.parse_response(h.getfile())

    def make_connection(self, host):
        # create a HTTP connection object from a host descriptor
        import httplib
        return httplib.HTTP(host)

    def send_request(self, connection, handler, request_body):
        connection.putrequest("POST", handler)

    def send_host(self, connection, host):
        connection.putheader("Host", host)

    def send_user_agent(self, connection):
        connection.putheader("User-Agent", self.user_agent)

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

    def parse_response(self, f):
        # read response from input file, and parse it

        p, u = getparser()

        while 1:
            response = f.read(1024)
            if not response:
                break
            if self.verbose:
                print "body:", repr(response)
            p.feed(response)

        f.close()
        p.close()

        return u.close()

class SafeTransport(Transport):
    """Handles an HTTPS transaction to an XML-RPC server"""

    def make_connection(self, host):
        # create a HTTPS connection object from a host descriptor
        # host may be a string, or a (host, x509-dict) tuple
        import httplib
        if isinstance(host, TupleType):
            host, x509 = host
        else:
            x509 = {}
        try:
            HTTPS = httplib.HTTPS
        except AttributeError:
            raise NotImplementedError,\
                  "your version of httplib doesn't support HTTPS"
        else:
            return apply(HTTPS, (host, None), x509)

    def send_host(self, connection, host):
        if isinstance(host, TupleType):
            host, x509 = host
        connection.putheader("Host", host)

class ServerProxy:
    """uri [,options] -> a logical connection to an XML-RPC server

    uri is the connection point on the server, given as
    scheme://host/target.

    The standard implementation always supports the "http" scheme.  If
    SSL socket support is available (Python 2.0), it also supports
    "https".

    If the target part and the slash preceding it are both omitted,
    "/RPC2" is assumed.

    The following options can be given as keyword arguments:

        transport: a transport factory
        encoding: the request encoding (default is UTF-8)

    All 8-bit strings passed to the server proxy are assumed to use
    the given encoding.
    """

    def __init__(self, uri, transport=None, encoding=None, verbose=0):
        # establish a "logical" server connection

        # get the url
        type, uri = urllib.splittype(uri)
        if type not in ("http", "https"):
            raise IOError, "unsupported XML-RPC protocol"
        self.__host, self.__handler = urllib.splithost(uri)
        if not self.__handler:
            self.__handler = "/RPC2"

        if transport is None:
            if type == "https":
                transport = SafeTransport()
            else:
                transport = Transport()
        self.__transport = transport

        self.__encoding = encoding
        self.__verbose = verbose

    def __request(self, methodname, params):
        # call a method on the remote server

        request = dumps(params, methodname, encoding=self.__encoding)

        response = self.__transport.request(
            self.__host,
            self.__handler,
            request,
            verbose=self.__verbose
            )

        if len(response) == 1:
            response = response[0]

        return response

    def __repr__(self):
        return (
            "<ServerProxy for %s%s>" %
            (self.__host, self.__handler)
            )

    __str__ = __repr__

    def __getattr__(self, name):
        # magic method dispatcher
        return _Method(self.__request, name)

    # note: to call a remote object with an non-standard name, use
    # result getattr(server, "strange-python-name")(args)

# compatibility
Server = ServerProxy

# --------------------------------------------------------------------
# test code

if __name__ == "__main__":

    # simple test program (from the XML-RPC specification)

    # server = ServerProxy("http://localhost:8000") # local server
    server = ServerProxy("http://betty.userland.com")

    print server

    try:
        print server.examples.getStateName(41)
    except Error, v:
        print "ERROR", v