jsonrpc/.svn/text-base/serviceHandler.py.svn-base

   1
   2 """
   3   Copyright (c) 2007 Jan-Klaas Kollhof
   4
   5   This file is part of jsonrpc.
   6
   7   jsonrpc is free software; you can redistribute it and/or modify
   8   it under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   This software is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with this software; if not, write to the Free Software
  19   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20 """
  21
  22 from jsonrpc import loads, dumps, JSONEncodeException
  23
  24
  25 def ServiceMethod(fn):
  26     fn.IsServiceMethod = True
  27     return fn
  28
  29 class ServiceException(Exception):
  30     pass
  31
  32 class ServiceRequestNotTranslatable(ServiceException):
  33     pass
  34
  35 class BadServiceRequest(ServiceException):
  36     pass
  37
  38 class ServiceMethodNotFound(ServiceException):
  39     def __init__(self, name):
  40         self.methodName=name
  41
  42 class ServiceHandler(object):
  43
  44     def __init__(self, service):
  45         self.service=service
  46
  47     def handleRequest(self, json):
  48         err=None
  49         result = None
  50         id_=''
  51
  52         try:
  53             req = self.translateRequest(json)
  54         except ServiceRequestNotTranslatable, e:
  55             err = e
  56             req={'id':id_}
  57
  58         if err==None:
  59             try:
  60                 id_ = req['id']
  61                 methName = req['method']
  62                 args = req['params']
  63             except:
  64                 err = BadServiceRequest(json)
  65
  66         if err == None:
  67             try:
  68                 meth = self.findServiceEndpoint(methName)
  69             except Exception, e:
  70                 err = e
  71
  72         if err == None:
  73             try:
  74                 result = self.invokeServiceEndpoint(meth, args)
  75             except Exception, e:
  76                 err = e
  77
  78         resultdata = self.translateResult(result, err, id_)
  79
  80         return resultdata
  81
  82     def translateRequest(self, data):
  83         try:
  84             req = loads(data)
  85         except:
  86             raise ServiceRequestNotTranslatable(data)
  87         return req
  88
  89     def findServiceEndpoint(self, name):
  90         try:
  91             meth = getattr(self.service, name)
  92             if getattr(meth, "IsServiceMethod"):
  93                 return meth
  94             else:
  95                 raise ServiceMethodNotFound(name)
  96         except AttributeError:
  97             raise ServiceMethodNotFound(name)
  98
  99     def invokeServiceEndpoint(self, meth, args):
 100         return meth(*args)
 101
 102     def translateResult(self, rslt, err, id_):
 103         if err != None:
 104             err = {"name": err.__class__.__name__, "message":err.message}
 105             rslt = None
 106
 107         try:
 108             data = dumps({"result":rslt,"id":id_,"error":err})
 109         except JSONEncodeException, e:
 110             err = {"name": "JSONEncodeException", "message":"Result Object Not Serializable"}
 111             data = dumps({"result":None, "id":id_,"error":err})
 112
 113         return data