Run a Jasper Reports report from a Python script

I am developing a Python application and I want to use Jasper Reports as a report generator. My purpose is only to launch a report that is in a repository of Jasper Reports . The JasperServer server is working and I have designed reports using iReport . However, when I try to launch using resquest the report always gives me 404 error (it does not find the resource).

I have created a Python class to create the requests , just like this:

# -*- coding: utf-8 -*-

import requests
import webbrowser
from datetime import datetime
import hashlib
import os


# 23-10-2016 Módulo de Jasper Reports.

class jasperreports(object):
    '''Clase de configuración de informes para Jasper Reports'''

    def __init__(self, maquina, puerto, recurso):
        self.__maquina = maquina
        self.__puerto = puerto
        self.__recurso = recurso
        self.__session = requests.Session()
        self.__token = self.__generador_token()

    def __generador_token(self):
        '''Generador de token'''
        return hashlib.sha1(os.urandom(128)).hexdigest()

    def login(self, usuario, passwd):
        '''Clase login para acceso a JasperServer'''

        url = "http://%s:%s/jasperserver/rest_v2/login" % (self.__maquina, \
                                                           self.__puerto)

        data = "j_username=%s&j_password=%s" % (usuario, passwd) 
        header = {"content-type" : "application/x-www-form-urlencoded"}

        ret = self.__session.post(url, data, headers = header)
        self.__cookie = ret.cookies['JSESSIONID']

        print ret

    def report(self, path_report, report, format_ = None, params = None):
        url = 'http://%s:%s/%s/rest_v2/reports/%s/%s' % (self.__maquina, \
                                                         str(self.__puerto), \
                                                         self.__recurso, \
                                                         path_report, \
                                                         report)
        headers = {"Authorization": "Basic " + self.__token,
                   "Accept": "application/json",
                   "Content-Type": "application/xml"}           

        auth = ('jasperadmin', 'jasperadmin')
        cookies = dict(cookies=self.__cookie)
        ret = self.__session.get(url, headers = headers, auth = \
                                 ('jasperadmin', 'jasperadmin'), cookies = cookies) 

        try:
            webbrowser.open(ret)
        except:
            nomfich = 'temp_error_%s.html' % str(datetime.now())
            f = open('temp/%s' % nomfich,'w')
            f.write(ret.text)
            f.close()    
            webbrowser.open('temp/%s' % nomfich)


    def info(self):
        url = 'http://%s:%s/%s/rest_v2/serverInfo' % (self.__maquina, \
                                                  str(self.__puerto), \
                                                  self.__recurso)

        # Se realiza petición de información al servidor JasperServer... 
        ret = requests.get(url,headers={"accept":"application/json"}).json()

        # Se recupera información del servidor si todo ha ido bien...
        data = { 'dateFormatPattern' : ret['dateFormatPattern'],
                 'datetimeFormatPattern' : ret['datetimeFormatPattern'],
                 'version' : ret['version'],
                 'edition' : ret['edition'],
                 'build' : ret['edition']
                 }

        # Se devuelven datos.
        return data

Well, I urge the class:

jr = jasperreports("localhost", 8080, "jasperserver")
jr.login('jasperadmin', 'jasperadmin')
jr.report('wshifts/Corporativo', 'usuario', 'jprint') 

I understand, reading the documentation of JasperReports, that it is not necessary to use SOAP, that with rest_v2 it is enough. Well, when I try to access the report I get 404 error . I think I'm leaving something, but I do not know what it is. It generates the cookie perfectly and it seems that it is not a token problem.