2

我有 XML-RPC 服务器：

import time

import xmlrpclib
from SimpleXMLRPCServer import SimpleXMLRPCServer

class Worker(object):
    def start_work(self):
        # is it possible do return value to client here?
        self.do_work()
        return 'we started!'

    def do_work(self):
        while(True):
            print 'I\'m doing work...'
            time.sleep(3)


if __name__ == '__main__':
    port = 8080
    server = SimpleXMLRPCServer(("localhost", port))
    print "Listening on port %s..." % port

    w = Worker()

    server.register_function(w.start_work)
    while(1):
        server.handle_request()

# vim: filetype=python syntax=python expandtab shiftwidth=4 softtabstop=4 encoding=utf8

和简单的客户：

import xmlrpclib
c = xmlrpclib.ServerProxy('http://localhost:8080/')
print c.start_work()

当然 start_work 函数返回的值永远不会被打印出来。

我的问题是如何在完成工作之前重写服务器代码以使返回值成为可能。我知道我可以为此使用线程，但我想确定没有更简单的方法。

4

2 回答 2

4

如果您希望 XML-RPC 具有长时间运行、提前返回的任务，您可能需要将服务器重写为异步框架，例如twisted

于 2011-08-18T16:56:11.147 回答
1

I'm not sure this is a good idea to do such a thing without threads or without reimplement some parts of the SimpleXMLRPCServer or without breaking XMLRPC protocol, however you can get an early answer by using a yield statement in your called method :

class Worker(object):
    def start_work(self):
        # is it possible do return value to client here?
        # yes, with a yield
        yield "the_return_value"
        self.do_work()
        # but yielding a first value and returning it to client will disable any next response
        # return 'we started!'

    def do_work(self):
        while(True):
            print 'I\'m doing work...'
            time.sleep(3)

And overriding the do_POST method of the SimpleXMLRPCRequestHandler to call twice the called method (everything around the ### parts are the standard part of python code)

class MySimpleXMLRPCRequestHandler(SimpleXMLRPCRequestHandler):

    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 server's _dispatch method for handling.
        """
        # Check that the path is legal
        if not self.is_rpc_path_valid():
            self.report_404()
            return

        try:
            # Get arguments by reading body of request.
            # We read this in chunks to avoid straining
            # socket.read(); around the 10 or 15Mb mark, some platforms
            # begin to have problems (bug #792570).
            max_chunk_size = 10*1024*1024
            size_remaining = int(self.headers["content-length"])
            L = []
            while size_remaining:
                chunk_size = min(size_remaining, max_chunk_size)
                L.append(self.rfile.read(chunk_size))
                size_remaining -= len(L[-1])
            data = ''.join(L)

            # In previous versions of SimpleXMLRPCServer, _dispatch
            # could be overridden in this class, instead of in
            # SimpleXMLRPCDispatcher. To maintain backwards compatibility,
            # check to see if a subclass implements _dispatch and dispatch
            # using that method if present.
            response = self.server._marshaled_dispatch(
                    data, getattr(self, '_dispatch', None)
                )
            ##############################################
            ##############################################
            ## Here you'll have the first part of your response
            response = response.next() # to get the first item of the generator (yes, a little bit uggly)
            ##############################################
            ##############################################
        except Exception, e: # This should only happen if the module is buggy
            # internal error, report as HTTP server error
            self.send_response(500)

            # Send information about the exception if requested
            if hasattr(self.server, '_send_traceback_header') and \
                    self.server._send_traceback_header:
                self.send_header("X-exception", str(e))
                self.send_header("X-traceback", traceback.format_exc())

            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)

            ##############################################
            ##############################################
            ## Here you've send the the first part of your response to the client, relaunch the method
            self.server._marshaled_dispatch(
                    data, getattr(self, '_dispatch', None)
            )
            ##############################################
            ##############################################

Then, the main will become : 

if __name__ == '__main__':
    port = 8080
    server = SimpleXMLRPCServer(("localhost", port), requestHandler=MySimpleXMLRPCRequestHandler)
    print "Listening on port %s..." % port

    w = Worker()

    server.register_function(w.start_work)
    while(1):
        server.handle_request()
于 2011-08-18T15:04:39.293 回答