Unable to make http request to django server using twisted.web.client.AGENT

[Akshat Tripathi]

I have written a basic tcp server factory, server client and a service using twisted. The tcp server acts as the middleware between a django server and an another program (let's call it client program).

What I want to achieve -

1.client requests the middleware tcp server;

2.it sends a string as the request body;

3.the middleware tcp server deserializes information from the request.

4.middleware furthers the serialized information to the django server.

5.The django server then responds to the middleware server which furthers the response to the client after serializing the response.

I am able to reach till step 3, but am unable to make any http request to the django server.




The following is my middleware.py

from twisted.internet.protocol import ServerFactory
from twisted.internet.protocol import Protocol

from test_service import MyService


class TCPServerProtocol(Protocol):
    data = ''

    def connectionMade(self):
        self.deferred = self.factory.service.deferred
        self.deferred.addCallback(self.factory.service.s)
        self.deferred.addCallback(self.transport.write)
        self.deferred.addBoth(lambda r: self.transport.loseConnection)

    def dataReceived(self, data):
        self.data += data

    def connectionLost(self, reason):
        self.forward(self.data)

    def forward(self, data):
        if self.deferred is not None:
            d, self.deferred = self.deferred, None
            d.callback(data)

class TCPServerFactory(ServerFactory):

    protocol = TCPServerProtocol

    def __init__(self, service):
        self.service = service

def runserver(ip, port):
    iface =  {'home': '192.168.0.104', 'work': '127.0.0.1'}
    service = MyService()
    factory = TCPServerFactory(service)
    from twisted.internet import reactor
    reactor.listenTCP(port=port, factory=factory, interface=iface[ip])
    reactor.run()

if __name__ == '__main__':
    import sys
    ip = sys.argv[1]
    port = int(sys.argv[2])
    runserver(ip, port)




The following is test_service.py

from twisted.internet.defer import Deferred

from test_http_client import HTTPClientFactory

class MyService(object):
    def __init__(self):
        self.deferred = Deferred()

    def s(self, data):
        kwargs = {}
        kwargs['url'] = b'http://127.0.0.1:8000/some/end/point'
        kwargs['url'] = kwargs['url'].encode('latin-1')
        kwargs['method'] = 'POST'
        kwargs['data'] = data

        client = HTTPClientFactory(**kwargs)
        d = client.deferred
        return d


The following is test_http_client.py

from StringIO import StringIO
import json

from twisted.internet.protocol import Protocol
from twisted.internet.defer import Deferred
from twisted.web.client import Agent, FileBodyProducer
from twisted.web.http_headers import Headers


class HTTPClientProtocol(Protocol):
    def __init__(self, finished):
        self.finished = finished
        self.data = ''

    def dataReceived(self, data):
        print '----------Data Received by HTTPClientProtocol----------'
        print data
        self.data += data

    def connectionLost(self, reason):
        print '----------HTTP Client connection Lost----------'
        print reason.getErrorMessage()
        if self.finished is not None:
            print 'finished is not None'
            f, self.finished = self.finished, None
            f.callback(self.data)

class HTTPClientFactory(object):

    """
    Class handling communication with HTTP server.
    """

    def __init__(self, **kwargs):
        data = kwargs['data'] 
        try:
            body = FileBodyProducer(StringIO(json.dumps(data)))
            print '----------Request body object created----------'
        except Exception as e:
            print '----------Request body object creation FAILURE----------'
            print e
            return e  
        url = kwargs.get('url', None)
        method = kwargs.get('method', None)

        from twisted.internet import reactor
        agent = Agent(reactor)
        if not data:
            body = None

        self.deferred = agent.request(method,
                                    url,
                                    Headers({'Content-Type': ['application/json']}),
                                    bodyProducer=body)

        self.deferred.addCallback(self.get_response)

    def get_response(self, response):
        print 'Response received'
        finished = Deferred()
        response.deliverBody(HTTPClientProtocol(finished))
        return finished