twisted , return custom message to client after receiving request from client

Question

I have Written a simple code of http server and http client, i am able to successfully send messages to server in form of xml from client. here's my code.

client.py

from StringIO import StringIO
from twisted.internet import reactor
from twisted.web.client import Agent
from twisted.web.http_headers import Headers

from twisted.web.client import FileBodyProducer
from xml_dict import bm_xml

xml_str = bm_xml()
agent = Agent(reactor)
body = FileBodyProducer(StringIO(xml_str))

d = agent.request(
   'GET',
   'http://localhost:8080/',
    Headers({'User-Agent': ['Replication'],
            'Content-Type': ['text/x-greeting']}),
    body)

def cbResponse(response):
    print response.version
d.addCallback(cbResponse)

def cbShutdown(ignored):
   reactor.stop()
d.addBoth(cbShutdown)

reactor.run()

server.py

from twisted.web import server, resource
from twisted.internet import reactor

def parse_xml(xml_str):
  print xml_str
  response = "xml_to_client"
  return response



class Simple(resource.Resource):
     isLeaf = True
     def render_GET(self, request):
        xml_request_str = request.content.read()
        response = parse_xml(xml_request_str)
        print response

 site = server.Site(Simple())
 reactor.listenTCP(8080, site) 
 reactor.run()

what i am trying to do here is from client i am sending an xml string to server, xml is generated from bm_xml module which is another file. this xml is successfully read to server, now once once server receives the xml, i need to parse this xml and return another xml string. i have the code to parse xml and construct another xml so that client receives this xml from server, but i do not know how to send the message to client from server. where all the changes would the required , in server or client ? i am assuming cbresponse is the one where changes has to be done in client , but i have no idea where the change should be done in server side. In server response variable is the one which i need to send to client.

Answer 1

You code appears to already do what you are asking. Simple.render_GET returns response. response is what is sent to the client. Perhaps you're unsure how to get the response after it has been sent to the client? If so, the answer may be readBody (more docs).

Answer 2

I found what i wanted : this is my updated Code for client.py

 from StringIO import StringIO

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

 from twisted.web.client import FileBodyProducer
 from xml_dict import bm_xml

 xml_str = bm_xml()
 agent = Agent(reactor)
 body = FileBodyProducer(StringIO(xml_str))

 class BeginningPrinter(Protocol):
     def __init__(self, finished):
         self.finished = finished
         self.remaining = 1024 * 10

     def dataReceived(self, bytes):
        if self.remaining:
            reply = bytes[:self.remaining]
            print reply

    def connectionLost(self, reason):
         print 'Finished receiving body:', reason.getErrorMessage()
         self.finished.callback(None)


  d = agent.request(
   'POST',
   'http://localhost:8080/',
    Headers({'User-Agent': ['Replication'],
            'Content-Type': ['text/x-greeting']}),
    body)

  def cbRequest(response):
      finished = Deferred()
      response.deliverBody(BeginningPrinter(finished))
      return finished

  d.addCallback(cbRequest)

  def cbShutdown(ignored):
  reactor.stop()

  d.addBoth(cbShutdown)
  reactor.run()

and this is my server.py

  from twisted.web import server, resource
  from twisted.internet import reactor
  from xml_parser import parser
  from twisted.web.resource import Resource

  def parse_xml(xml_str):
       print xml_str
       xml_response = parser(xml_str)
       return xml_response

 class re_simple(Resource):
       isLeaf = True
       def render_POST(self, request):
            xml_request_str = request.content.read()
            xml_response = parse_xml(xml_request_str)
            return xml_response

 site = server.Site(re_simple())
 reactor.listenTCP(8080, site)
 print "server started"
 reactor.run()

Now i send the Request : <some Xml> to server and i get the response from server <some response> .

this is what i wanted.