source: TI04-geosplat/trunk/pygsc/WSCaller.py @ 798

#   Copyright (C) 2004 CCLRC & NERC( Natural Environment Research Council ).
#   This software may be distributed under the terms of the
#   Q Public License, version 1.0 or later. http://ndg.nerc.ac.uk/public_docs/QPublic_license.txt

"""
WSCaller.py
===========

Holds the WSCaller class used to make calls to the Web Service
across the network to a remote server.

"""

# Import standard library modules
import os, sys

# Import SOAP library
from ZSI.client import Binding

# Import package modules
from clientConfig import *
from common import *
from DisplayManager import DisplayManager


class WSCaller:
    """
    Used to call Web Service on a remote machine.
    """         
    
    def __init__(self):
        """
        Sets up the instance.
        """
        # Set up SOAP bindings
        trace=open('/tmp/tracefile.txt','w')
        self.server=Binding(url='', host=SOAP_SERVER_NAME, port=SOAP_SERVER_PORT, tracefile=trace)              


    def callServerMethod(self, methodName, args, packArgs=None):
        """

        Calls method "methodName(args)" and returns whatever is returned.
        """
        if packArgs:
            args=self._packArgsAsList(args)
        
        # Make that call
        try:
            response=apply(getattr(self.server, methodName), args) 
        except Exception, error:
            if str(error)=="(111, 'Connection refused')":
                error="GeoSPlAT server is currently unavailable. Please try again later."
            self._displayErrorPage(error)
        response=self._webServiceCallWrapper(response)
        return response
        
        
    def _packArgsAsList(self, args):
        """
        In order to work with ZSI SOAP library need to pack up arguments as a list 
        of [keyword, value] pairs rather than a dictionary.
        """
        newList=[]
        for key, value in args.items():
            newList.append([key, value])
        return newList
        

    def _deUnicodeObject(self, obj):
        """
        Returns an identical object with all unicode strings returned as normal strings.
        """
        return deUnicodeObject(obj)     
        

    def _webServiceCallWrapper(self, response):
        """
        Analyses the response from a Web Service call to check if an error has
        occurred. If so it parses and reports the error. Otherwise it returns  
        the object returned from the Web Service call.
        """
        if type(response) in (type(""), type(u'w')):
            # String returns are errors
            self._displayErrorPage(response)
        else:
            return response


    def _displayErrorPage(self, error):
        """
        Displays the error if one is found.
        """
        self.displayer=DisplayManager()
        self.displayer._displayErrorPage(error)
        if DEBUG==1: raise Exception, error
        sys.exit()