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— courses:ct30a6000:hw_02 [2012/01/30 15:11] (current)
hevi created
Line 1: Line 1:
 +====== Homework 02, message coding \ CSPA ======
 +
 +Complete library system messages codings started on exercises [[exer_codec]].
 +
 +Code to point
 +
 +In python package **exer_codec**
 +
 +**codec.py**
 +<​code>​
 +from exer_codec.interfaces import *
 +import struct
 +import logging
 +log = logging.getLogger(__name__)
 +from util.common import *
 +
 +class list_items(list_items_pdu):​
 +  def __init__(self):​
 +    super(list_items,​self).__init__()
 +    ​
 +  def encode(self):​
 +    """​ Encode the fields into data buffer.
 +    Return data buffer."""​
 +    self.msgtype = 1
 +    self.msgsize = struct.calcsize("​HH"​) ​
 +    buf = str() ## Python 2 data buffer
 +    buf += struct.pack("​HH",​ self.msgtype,​ self.msgsize)
 +    log.debug(buf_debug(buf))
 +    return buf    ​
 +  ​
 +  def decode(self,​buf):​
 +    """​ Decode the buffer into message fields. """​
 +    log.debug(buf_debug(buf)) ​   ​
 +    offset = 0
 +    ## REMEMBER TUPLE RETURN !
 +    self.msgtype = struct.unpack("​H",​buf[offset:​offset + 2])[0]
 +    offset += 2
 +    self.msgsize = struct.unpack("​H",​buf[offset:​offset + 2])[0]
 +</​code>​
 +
 +**interfaces.py**
 +<​code>​
 +'''​
 +Created on 30.1.2012
 +
 +@author: hevi
 +'''​
 +
 +## PDU definitions
 +
 +class Message_pdu(object):​
 +  def __init__(self):​
 +    self.msgtype = -1
 +    self.msgsize = -1
 +    ​
 +class list_items_pdu(Message_pdu):​
 +  def __init__(self):​
 +    super(list_items_pdu,​self).__init__()
 +    ​
 +class list_info_pdu(Message_pdu):​
 +  def __init__(self):​
 +    super(list_info_pdu,​self).__init__()
 +    self.itemid = -1
 +
 +class receive_item_pdu(Message_pdu):​
 +  def __init__(self):​
 +    super(receive_item_pdu,​self).__init__()
 +    self.itemid = -1
 +    self.userid = -1
 +
 +class list_item_reply_pdu(Message_pdu):​
 +  def __init__(self):​
 +    super(list_item_reply_pdu,​self).__init__()
 +    self.itemids = list() # list of itemid
 +    ​
 +class BOOK_info(object):​
 +  def __init__(self):​
 +    self.itemstatus = -1
 +    self.language = None
 +    self.title = None
 +    self.authors = list() # list of str
 +    self.ISBN = None
 +    self.year = -1
 +    self.classification = None
 +    ​
 +class JOURNAL_info(object):​
 +  def __init__(self):​
 +    self.itemstatus = -1
 +    self.language = None
 +    self.name = None
 +    self.year = -1
 +    self.issue = -1
 +    self.ISSN = None
 +    ​
 +    ​
 +class item_info_reply_pdu(Message_pdu):​
 +  def __init__(self):​
 +    super(item_info_reply_pdu,​self).__init__()
 +    self.itemid = -1
 +    self.itemtype = -1
 +    self.subblock = None # either Book_info or JOURNAL_info object
 +
 +class OperationSuccess_pdu(Message_pdu): ​   ​
 +  def __init__(self): ​
 +    super(OperationSuccess_pdu,​self).__init__()
 +    self.reason = None
 +</​code>​
 +
 +**test_codec.py**
 +<​code>​
 +'''​
 +Created on 30.1.2012
 +
 +@author: hevi
 +'''​
 +import unittest
 +from exer_codec.codec import *
 +import logging
 +log = logging.getLogger(__name__)
 +
 +
 +class Test(unittest.TestCase):​
 +
 +  def test_list_items_01(self):​
 +    msg_send = list_items()
 +    buf = msg_send.encode()
 +    msg_recv = list_items()
 +    msg_recv.decode(buf)
 +    ## checking
 +    log.debug(str(msg_send.msgtype))
 +    log.debug(str(msg_recv.msgtype))
 +    assert msg_send.msgtype == msg_recv.msgtype
 +    assert msg_send.msgsize == msg_recv.msgsize
 +
 +
 +if __name__ == "​__main__":​
 +    #import sys;​sys.argv = ['',​ '​Test.testName'​]
 +    logging.basicConfig(level=logging.DEBUG)
 +    unittest.main()
 +</​code>​