diff options
Diffstat (limited to 'Doc/library/xmlrpclib.rst')
| -rw-r--r-- | Doc/library/xmlrpclib.rst | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/Doc/library/xmlrpclib.rst b/Doc/library/xmlrpclib.rst new file mode 100644 index 0000000..cd507c4 --- /dev/null +++ b/Doc/library/xmlrpclib.rst @@ -0,0 +1,422 @@ + +:mod:`xmlrpclib` --- XML-RPC client access +========================================== + +.. module:: xmlrpclib + :synopsis: XML-RPC client access. +.. moduleauthor:: Fredrik Lundh <fredrik@pythonware.com> +.. sectionauthor:: Eric S. Raymond <esr@snark.thyrsus.com> + + +.. % Not everything is documented yet. It might be good to describe +.. % Marshaller, Unmarshaller, getparser, dumps, loads, and Transport. + +.. versionadded:: 2.2 + +XML-RPC is a Remote Procedure Call method that uses XML passed via HTTP as a +transport. With it, a client can call methods with parameters on a remote +server (the server is named by a URI) and get back structured data. This module +supports writing XML-RPC client code; it handles all the details of translating +between conformable Python objects and XML on the wire. + + +.. class:: ServerProxy(uri[, transport[, encoding[, verbose[, allow_none[, use_datetime]]]]]) + + A :class:`ServerProxy` instance is an object that manages communication with a + remote XML-RPC server. The required first argument is a URI (Uniform Resource + Indicator), and will normally be the URL of the server. The optional second + argument is a transport factory instance; by default it is an internal + :class:`SafeTransport` instance for https: URLs and an internal HTTP + :class:`Transport` instance otherwise. The optional third argument is an + encoding, by default UTF-8. The optional fourth argument is a debugging flag. + If *allow_none* is true, the Python constant ``None`` will be translated into + XML; the default behaviour is for ``None`` to raise a :exc:`TypeError`. This is + a commonly-used extension to the XML-RPC specification, but isn't supported by + all clients and servers; see http://ontosys.com/xml-rpc/extensions.php for a + description. The *use_datetime* flag can be used to cause date/time values to + be presented as :class:`datetime.datetime` objects; this is false by default. + :class:`datetime.datetime`, :class:`datetime.date` and :class:`datetime.time` + objects may be passed to calls. :class:`datetime.date` objects are converted + with a time of "00:00:00". :class:`datetime.time` objects are converted using + today's date. + + Both the HTTP and HTTPS transports support the URL syntax extension for HTTP + Basic Authentication: ``http://user:pass@host:port/path``. The ``user:pass`` + portion will be base64-encoded as an HTTP 'Authorization' header, and sent to + the remote server as part of the connection process when invoking an XML-RPC + method. You only need to use this if the remote server requires a Basic + Authentication user and password. + + The returned instance is a proxy object with methods that can be used to invoke + corresponding RPC calls on the remote server. If the remote server supports the + introspection API, the proxy can also be used to query the remote server for the + methods it supports (service discovery) and fetch other server-associated + metadata. + + :class:`ServerProxy` instance methods take Python basic types and objects as + arguments and return Python basic types and classes. Types that are conformable + (e.g. that can be marshalled through XML), include the following (and except + where noted, they are unmarshalled as the same Python type): + + +---------------------------------+---------------------------------------------+ + | Name | Meaning | + +=================================+=============================================+ + | :const:`boolean` | The :const:`True` and :const:`False` | + | | constants | + +---------------------------------+---------------------------------------------+ + | :const:`integers` | Pass in directly | + +---------------------------------+---------------------------------------------+ + | :const:`floating-point numbers` | Pass in directly | + +---------------------------------+---------------------------------------------+ + | :const:`strings` | Pass in directly | + +---------------------------------+---------------------------------------------+ + | :const:`arrays` | Any Python sequence type containing | + | | conformable elements. Arrays are returned | + | | as lists | + +---------------------------------+---------------------------------------------+ + | :const:`structures` | A Python dictionary. Keys must be strings, | + | | values may be any conformable type. Objects | + | | of user-defined classes can be passed in; | + | | only their *__dict__* attribute is | + | | transmitted. | + +---------------------------------+---------------------------------------------+ + | :const:`dates` | in seconds since the epoch (pass in an | + | | instance of the :class:`DateTime` class) or | + | | a :class:`datetime.datetime`, | + | | :class:`datetime.date` or | + | | :class:`datetime.time` instance | + +---------------------------------+---------------------------------------------+ + | :const:`binary data` | pass in an instance of the :class:`Binary` | + | | wrapper class | + +---------------------------------+---------------------------------------------+ + + This is the full set of data types supported by XML-RPC. Method calls may also + raise a special :exc:`Fault` instance, used to signal XML-RPC server errors, or + :exc:`ProtocolError` used to signal an error in the HTTP/HTTPS transport layer. + Both :exc:`Fault` and :exc:`ProtocolError` derive from a base class called + :exc:`Error`. Note that even though starting with Python 2.2 you can subclass + builtin types, the xmlrpclib module currently does not marshal instances of such + subclasses. + + When passing strings, characters special to XML such as ``<``, ``>``, and ``&`` + will be automatically escaped. However, it's the caller's responsibility to + ensure that the string is free of characters that aren't allowed in XML, such as + the control characters with ASCII values between 0 and 31 (except, of course, + tab, newline and carriage return); failing to do this will result in an XML-RPC + request that isn't well-formed XML. If you have to pass arbitrary strings via + XML-RPC, use the :class:`Binary` wrapper class described below. + + :class:`Server` is retained as an alias for :class:`ServerProxy` for backwards + compatibility. New code should use :class:`ServerProxy`. + + .. versionchanged:: 2.5 + The *use_datetime* flag was added. + + .. versionchanged:: 2.6 + Instances of new-style classes can be passed in if they have an *__dict__* + attribute and don't have a base class that is marshalled in a special way. + + +.. seealso:: + + `XML-RPC HOWTO <http://www.tldp.org/HOWTO/XML-RPC-HOWTO/index.html>`_ + A good description of XML operation and client software in several languages. + Contains pretty much everything an XML-RPC client developer needs to know. + + `XML-RPC Hacks page <http://xmlrpc-c.sourceforge.net/hacks.php>`_ + Extensions for various open-source libraries to support introspection and + multicall. + + +.. _serverproxy-objects: + +ServerProxy Objects +------------------- + +A :class:`ServerProxy` instance has a method corresponding to each remote +procedure call accepted by the XML-RPC server. Calling the method performs an +RPC, dispatched by both name and argument signature (e.g. the same method name +can be overloaded with multiple argument signatures). The RPC finishes by +returning a value, which may be either returned data in a conformant type or a +:class:`Fault` or :class:`ProtocolError` object indicating an error. + +Servers that support the XML introspection API support some common methods +grouped under the reserved :attr:`system` member: + + +.. method:: ServerProxy.system.listMethods() + + This method returns a list of strings, one for each (non-system) method + supported by the XML-RPC server. + + +.. method:: ServerProxy.system.methodSignature(name) + + This method takes one parameter, the name of a method implemented by the XML-RPC + server.It returns an array of possible signatures for this method. A signature + is an array of types. The first of these types is the return type of the method, + the rest are parameters. + + Because multiple signatures (ie. overloading) is permitted, this method returns + a list of signatures rather than a singleton. + + Signatures themselves are restricted to the top level parameters expected by a + method. For instance if a method expects one array of structs as a parameter, + and it returns a string, its signature is simply "string, array". If it expects + three integers and returns a string, its signature is "string, int, int, int". + + If no signature is defined for the method, a non-array value is returned. In + Python this means that the type of the returned value will be something other + that list. + + +.. method:: ServerProxy.system.methodHelp(name) + + This method takes one parameter, the name of a method implemented by the XML-RPC + server. It returns a documentation string describing the use of that method. If + no such string is available, an empty string is returned. The documentation + string may contain HTML markup. + +Introspection methods are currently supported by servers written in PHP, C and +Microsoft .NET. Partial introspection support is included in recent updates to +UserLand Frontier. Introspection support for Perl, Python and Java is available +at the `XML-RPC Hacks <http://xmlrpc-c.sourceforge.net/hacks.php>`_ page. + + +.. _boolean-objects: + +Boolean Objects +--------------- + +This class may be initialized from any Python value; the instance returned +depends only on its truth value. It supports various Python operators through +:meth:`__cmp__`, :meth:`__repr__`, :meth:`__int__`, and :meth:`__bool__` +methods, all implemented in the obvious ways. + +It also has the following method, supported mainly for internal use by the +unmarshalling code: + + +.. method:: Boolean.encode(out) + + Write the XML-RPC encoding of this Boolean item to the out stream object. + + +.. _datetime-objects: + +DateTime Objects +---------------- + +This class may be initialized with seconds since the epoch, a time tuple, an ISO +8601 time/date string, or a :class:`datetime.datetime`, :class:`datetime.date` +or :class:`datetime.time` instance. It has the following methods, supported +mainly for internal use by the marshalling/unmarshalling code: + + +.. method:: DateTime.decode(string) + + Accept a string as the instance's new time value. + + +.. method:: DateTime.encode(out) + + Write the XML-RPC encoding of this :class:`DateTime` item to the *out* stream + object. + +It also supports certain of Python's built-in operators through :meth:`__cmp__` +and :meth:`__repr__` methods. + + +.. _binary-objects: + +Binary Objects +-------------- + +This class may be initialized from string data (which may include NULs). The +primary access to the content of a :class:`Binary` object is provided by an +attribute: + + +.. attribute:: Binary.data + + The binary data encapsulated by the :class:`Binary` instance. The data is + provided as an 8-bit string. + +:class:`Binary` objects have the following methods, supported mainly for +internal use by the marshalling/unmarshalling code: + + +.. method:: Binary.decode(string) + + Accept a base64 string and decode it as the instance's new data. + + +.. method:: Binary.encode(out) + + Write the XML-RPC base 64 encoding of this binary item to the out stream object. + +It also supports certain of Python's built-in operators through a +:meth:`__cmp__` method. + + +.. _fault-objects: + +Fault Objects +------------- + +A :class:`Fault` object encapsulates the content of an XML-RPC fault tag. Fault +objects have the following members: + + +.. attribute:: Fault.faultCode + + A string indicating the fault type. + + +.. attribute:: Fault.faultString + + A string containing a diagnostic message associated with the fault. + + +.. _protocol-error-objects: + +ProtocolError Objects +--------------------- + +A :class:`ProtocolError` object describes a protocol error in the underlying +transport layer (such as a 404 'not found' error if the server named by the URI +does not exist). It has the following members: + + +.. attribute:: ProtocolError.url + + The URI or URL that triggered the error. + + +.. attribute:: ProtocolError.errcode + + The error code. + + +.. attribute:: ProtocolError.errmsg + + The error message or diagnostic string. + + +.. attribute:: ProtocolError.headers + + A string containing the headers of the HTTP/HTTPS request that triggered the + error. + + +MultiCall Objects +----------------- + +.. versionadded:: 2.4 + +In http://www.xmlrpc.com/discuss/msgReader%241208, an approach is presented to +encapsulate multiple calls to a remote server into a single request. + + +.. class:: MultiCall(server) + + Create an object used to boxcar method calls. *server* is the eventual target of + the call. Calls can be made to the result object, but they will immediately + return ``None``, and only store the call name and parameters in the + :class:`MultiCall` object. Calling the object itself causes all stored calls to + be transmitted as a single ``system.multicall`` request. The result of this call + is a generator; iterating over this generator yields the individual results. + +A usage example of this class is :: + + multicall = MultiCall(server_proxy) + multicall.add(2,3) + multicall.get_address("Guido") + add_result, address = multicall() + + +Convenience Functions +--------------------- + + +.. function:: boolean(value) + + Convert any Python value to one of the XML-RPC Boolean constants, ``True`` or + ``False``. + + +.. function:: dumps(params[, methodname[, methodresponse[, encoding[, allow_none]]]]) + + Convert *params* into an XML-RPC request. or into a response if *methodresponse* + is true. *params* can be either a tuple of arguments or an instance of the + :exc:`Fault` exception class. If *methodresponse* is true, only a single value + can be returned, meaning that *params* must be of length 1. *encoding*, if + supplied, is the encoding to use in the generated XML; the default is UTF-8. + Python's :const:`None` value cannot be used in standard XML-RPC; to allow using + it via an extension, provide a true value for *allow_none*. + + +.. function:: loads(data[, use_datetime]) + + Convert an XML-RPC request or response into Python objects, a ``(params, + methodname)``. *params* is a tuple of argument; *methodname* is a string, or + ``None`` if no method name is present in the packet. If the XML-RPC packet + represents a fault condition, this function will raise a :exc:`Fault` exception. + The *use_datetime* flag can be used to cause date/time values to be presented as + :class:`datetime.datetime` objects; this is false by default. Note that even if + you call an XML-RPC method with :class:`datetime.date` or :class:`datetime.time` + objects, they are converted to :class:`DateTime` objects internally, so only + :class:`datetime.datetime` objects will be returned. + + .. versionchanged:: 2.5 + The *use_datetime* flag was added. + + +.. _xmlrpc-client-example: + +Example of Client Usage +----------------------- + +:: + + # simple test program (from the XML-RPC specification) + from xmlrpclib import ServerProxy, Error + + # server = ServerProxy("http://localhost:8000") # local server + server = ServerProxy("http://betty.userland.com") + + print server + + try: + print server.examples.getStateName(41) + except Error as v: + print "ERROR", v + +To access an XML-RPC server through a proxy, you need to define a custom +transport. The following example, written by NoboNobo, shows how: + +.. % fill in original author's name if we ever learn it + +.. % Example taken from http://lowlife.jp/nobonobo/wiki/xmlrpcwithproxy.html + +:: + + import xmlrpclib, httplib + + class ProxiedTransport(xmlrpclib.Transport): + def set_proxy(self, proxy): + self.proxy = proxy + def make_connection(self, host): + self.realhost = host + h = httplib.HTTP(self.proxy) + return h + def send_request(self, connection, handler, request_body): + connection.putrequest("POST", 'http://%s%s' % (self.realhost, handler)) + def send_host(self, connection, host): + connection.putheader('Host', self.realhost) + + p = ProxiedTransport() + p.set_proxy('proxy-server:8080') + server = xmlrpclib.Server('http://time.xmlrpc.com/RPC2', transport=p) + print server.currentTime.getCurrentTime() + |