Brian Quinlan's XML-RPC server framework.

Lib/SimpleXMLRPCServer.py

+"""Simple XML-RPC Server.
+
+This module can be used to create simple XML-RPC servers
+by creating a server and either installing functions, a
+class instance, or by extending the SimpleXMLRPCRequestHandler
+class.
+
+A list of possible usage patterns follows:
+
+1. Install functions:
+
+server = SimpleXMLRPCServer(("localhost", 8000))
+server.register_function(pow)
+server.register_function(lambda x,y: x+y, 'add')
+server.serve_forever()
+
+2. Install an instance:
+
+class MyFuncs:
+    def __init__(self):
+        # make all of the string functions available through
+        # string.func_name
+        import string
+        self.string = string
+    def pow(self, x, y): return pow(x, y)
+    def add(self, x, y) : return x + y
+server = SimpleXMLRPCServer(("localhost", 8000))
+server.register_instance(MyFuncs())
+server.serve_forever()
+
+3. Install an instance with custom dispatch method:
+
+class Math:
+    def _dispatch(self, method, params):
+        if method == 'pow':
+            return apply(pow, params)
+        elif method == 'add':
+            return params[0] + params[1]
+        else:
+            raise 'bad method'
+server = SimpleXMLRPCServer(("localhost", 8000))
+server.register_instance(Math())
+server.serve_forever()
+
+4. Subclass SimpleXMLRPCRequestHandler:
+
+class MathHandler(SimpleXMLRPCRequestHandler):
+    def _dispatch(self, method, params):
+        try:
+            # We are forcing the 'export_' prefix on methods that are
+            # callable through XML-RPC to prevent potential security
+            # problems
+            func = getattr(self, 'export_' + method)
+        except AttributeError:
+            raise Exception('method "%s" is not supported' % method)
+        else:
+            return apply(func, params)
+
+    def log_message(self, format, *args):
+        pass # maybe do something fancy like write the messages to a file
+
+    def export_add(self, x, y):
+        return x + y
+
+server = SimpleXMLRPCServer(("localhost", 8000), MathHandler)
+server.serve_forever()
+"""
+
+# Written by Brian Quinlan (brian@sweetapp.com).
+# Based on code written by Fredrik Lundh.
+
+import xmlrpclib
+import SocketServer
+import BaseHTTPServer
+import sys
+
+class SimpleXMLRPCRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
+    """Simple XML-RPC request handler class.
+
+    Handles all HTTP POST requests and attempts to decode them as
+    XML-RPC requests.
+
+    XML-RPC requests are dispatched to the _dispatch method, which
+    may be overriden by subclasses. The default implementation attempts
+    to dispatch XML-RPC calls to the functions or instance installed
+    in the server.
+    """
+
+    def do_POST(self):
+        """Handles the HTTP POST request.
+
+        Attempts to interpret all HTTP POST requests as XML-RPC calls,
+        which are forwarded to the _dispatch method for handling.
+        """
+
+        try:
+            # get arguments
+            data = self.rfile.read(int(self.headers["content-length"]))
+            params, method = xmlrpclib.loads(data)
+
+            # generate response
+            try:
+                response = self._dispatch(method, params)
+                # wrap response in a singleton tuple
+                response = (response,)
+            except:
+                # report exception back to server
+                response = xmlrpclib.dumps(
+                    xmlrpclib.Fault(1, "%s:%s" % (sys.exc_type, sys.exc_value))
+                    )
+            else:
+                response = xmlrpclib.dumps(response, methodresponse=1)
+        except:
+            # internal error, report as HTTP server error
+            self.send_response(500)
+            self.end_headers()
+        else:
+            # got a valid XML RPC response
+            self.send_response(200)
+            self.send_header("Content-type", "text/xml")
+            self.send_header("Content-length", str(len(response)))
+            self.end_headers()
+            self.wfile.write(response)
+
+            # shut down the connection
+            self.wfile.flush()
+            self.connection.shutdown(1)
+
+    def _dispatch(self, method, params):
+        """Dispatches the XML-RPC method.
+
+        XML-RPC calls are forwarded to a registered function that
+        matches the called XML-RPC method name. If no such function
+        exists then the call is forwarded to the registered instance,
+        if available.
+
+        If the registered instance has a _dispatch method then that
+        method will be called with the name of the XML-RPC method and
+        it's parameters as a tuple
+        e.g. instance._dispatch('add',(2,3))
+
+        If the registered instance does not have a _dispatch method
+        then the instance will be searched to find a matching method
+        and, if found, will be called.
+
+        Methods beginning with an '_' are considered private and will
+        not be called by SimpleXMLRPCServer.
+        """
+
+        def resolve_dotted_attribute(obj, attr):
+            """resolve_dotted_attribute(math, 'cos.__doc__') => math.cos.__doc__
+
+            Resolves a dotted attribute name to an object. Raises
+            an AttributeError if any attribute in the chain starts
+            with a '_'.
+            """
+            for i in attr.split('.'):
+                if i.startswith('_'):
+                    raise AttributeError(
+                        'attempt to access private attribute "%s"' % i
+                        )
+                else:
+                    obj = getattr(obj,i)
+            return obj
+
+        func = None
+        try:
+            # check to see if a matching function has been registered
+            func = self.server.funcs[method]
+        except KeyError:
+            if self.server.instance is not None:
+                # check for a _dispatch method
+                if hasattr(self.server.instance, '_dispatch'):
+                    return apply(
+                        getattr(self.server.instance,'_dispatch'),
+                        (method, params)
+                        )
+                else:
+                    # call instance method directly
+                    try:
+                        func = resolve_dotted_attribute(
+                            self.server.instance,
+                            method
+                            )
+                    except AttributeError:
+                        pass
+
+        if func is not None:
+            return apply(func, params)
+        else:
+            raise Exception('method "%s" is not supported' % method)
+
+    def log_request(self, code='-', size='-'):
+        """Selectively log an accepted request."""
+
+        if self.server.logRequests:
+            BaseHTTPServer.BaseHTTPRequestHandler.log_request(self, code, size)
+
+class SimpleXMLRPCServer(SocketServer.TCPServer):
+    """Simple XML-RPC server.
+
+    Simple XML-RPC server that allows functions and a single instance
+    to be installed to handle requests.
+    """
+
+    def __init__(self, addr, requestHandler=SimpleXMLRPCRequestHandler,
+                 logRequests=1):
+        self.funcs = {}
+        self.logRequests = logRequests
+        self.instance = None
+        SocketServer.TCPServer.__init__(self, addr, requestHandler)
+
+    def register_instance(self, instance):
+        """Registers an instance to respond to XML-RPC requests.
+
+        Only one instance can be installed at a time.
+
+        If the registered instance has a _dispatch method then that
+        method will be called with the name of the XML-RPC method and
+        it's parameters as a tuple
+        e.g. instance._dispatch('add',(2,3))
+
+        If the registered instance does not have a _dispatch method
+        then the instance will be searched to find a matching method
+        and, if found, will be called.
+
+        Methods beginning with an '_' are considered private and will
+        not be called by SimpleXMLRPCServer.
+
+        If a registered function matches a XML-RPC request, then it
+        will be called instead of the registered instance.
+        """
+
+        self.instance = instance
+
+    def register_function(self, function, name = None):
+        """Registers a function to respond to XML-RPC requests.
+
+        The optional name argument can be used to set a Unicode name
+        for the function.
+
+        If an instance is also registered then it will only be called
+        if a matching function is not found.
+        """
+
+        if name is None:
+            name = function.__name__
+        self.funcs[name] = function
+
+if __name__ == '__main__':
+    server = SimpleXMLRPCServer(("localhost", 8000))
+    server.register_function(pow)
+    server.register_function(lambda x,y: x+y, 'add')
+    server.serve_forever()