#!/usr/bin/env python
# @(#) $Id: acspyexmplFridgeNCClient.py,v 1.21 2006/03/30 17:45:14 dfugate Exp $
#*******************************************************************************
# ALMA - Atacama Large Millimiter Array
# (c) Associated Universities Inc., 2002 
# (c) European Southern Observatory, 2002
# Copyright by ESO (in the framework of the ALMA collaboration)
# and Cosylab 2002, All rights reserved
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, 
# MA 02111-1307  USA
# 

'''
DESCRIPTION
This example shows how to consume events from a notification channel in 
Python using the standard FRIDGE::temperatureDataBlockEvent example. Unlike
<a href="group__ACSPYEXMPLFRIDGENCCONSUMERDOC.html">Fridge Event Channel Consumer</a>,
this script forces events to be published by invoking some methods on a C++
<a href="../../idl/html/interfaceFRIDGE_1_1FridgeControl.html">Fridge</a>
component which contains a FRIDGE::temperatureDataBlockEvent event Supplier.

WHAT CAN I GAIN FROM THIS EXAMPLE?
- PySimpleClient usage.
- Accessing (remote) components.
- Consumer class usage.
- Consuming events.
- Implementation of so-called handler functions to process event data.

LINKS
- <a href="../../idl/html/interfaceFRIDGE_1_1FridgeControl.html">Fridge IDL Documentation</a>
'''
#--REGULAR IMPORTS-------------------------------------------------------------
from time import sleep
#--CORBA STUBS-----------------------------------------------------------------
import FRIDGE
from ACS import CBDescIn
#--ACS Imports-----------------------------------------------------------------
from Acspy.Nc.Consumer          import Consumer
from Acspy.Clients.SimpleClient import PySimpleClient
from Acspy.Common.Log           import getLogger
#--GLOBALS---------------------------------------------------------------------
#count is a global integer used to make sure we don't print more than five
#events to standard out.  really this is done just to make this module's modular
# test happy.
count = 0

LOGGER = getLogger("FridgeNCClient")

#------------------------------------------------------------------------------
def fridgeDataHandler(someParam):
    '''
    This function serves only one purpose...it must do something with the extracted
    data from the structured event.  That is, it must be capable of processing
    filterable_data[0].any in the structured event.  We can be certain of the real
    type of someParam because handlers are registered only for specific
    types (i.e., the type_name field of a structured event).

    Parameters: someParam is the real CORBA type extracted from the CORBA Any at
    filterable_data[0].  In this case, it will always be a FRIDGE.temperatureDataBlockEvent.

    Returns: event handler functions return nothing.

    Raises: If any exception is thrown by this function, the Consumer class will
    catch it and call processEvent(...) which will hopefully have been overriden.
    '''
    global count
    
    if count < 5:
        count = count + 1
        LOGGER.logInfo('The temperature difference is ' + str(someParam.absoluteDiff))
        
    return
#------------------------------------------------------------------------------
if __name__ == "__main__":
    
    print 'Making sure there is a fridge available...'
    
    #Start publishing events through a C++ Supplier
    simpleClient = PySimpleClient()
    aFridge = simpleClient.getComponent("FRIDGE1")
    aFridge.on()

    #Create a FridgeConsumer
    simpleClient.getLogger().logInfo('Creating FridgeConsumer')
    g = Consumer(FRIDGE.CHANNELNAME_FRIDGE)

    #Subscribe to temperatureDataBlockEvent events and register this handler to process
    #those events
    g.addSubscription(FRIDGE.temperatureDataBlockEvent, fridgeDataHandler)

    #Let the Notification Service know we are ready to start processing events.
    g.consumerReady()

    #After five events have been received, disconnect from the channel
    simpleClient.getLogger().logInfo("Waiting for events . . .")
    while(count<5):
        sleep(1)

    simpleClient.getLogger().logInfo("Events all done . . . exiting")
    g.disconnect()

    #Turn the C++ Fridge device off.
    aFridge.off()

    # Release it
    simpleClient.releaseComponent("FRIDGE1")

    simpleClient.disconnect()
#------------------------------------------------------------------------------