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The xdrlib module

This module converts between Python data types and Sun’s external data representation (XDR).

Example: Using the xdrlib module
# File: xdrlib-example-1.py

import xdrlib

#
# create a packer and add some data to it

p = xdrlib.Packer()
p.pack_uint(1)
p.pack_string("spam")

data = p.get_buffer()

print "packed:", repr(data)

#
# create an unpacker and use it to decode the data

u = xdrlib.Unpacker(data)

print "unpacked:", u.unpack_uint(), repr(u.unpack_string())

u.done()

$ python xdrlib-example-1.py
packed: '\000\000\000\001\000\000\000\004spam'
unpacked: 1 'spam'

The XDR format is used by Sun’s remote procedure call (RPC) protocol. Here’s an incomplete (and rather contrived) example showing how to build an RPC request package:

Example: Using the xdrlib module to send a RPC call package
# File: xdrlib-example-2.py

import xdrlib

# some constants (see the RPC specs for details)
RPC_CALL = 1
RPC_VERSION = 2

MY_PROGRAM_ID = 1234 # assigned by Sun
MY_VERSION_ID = 1000
MY_TIME_PROCEDURE_ID = 9999

AUTH_NULL = 0

transaction = 1

p = xdrlib.Packer()

# send an Sun RPC call package
p.pack_uint(transaction)
p.pack_enum(RPC_CALL)
p.pack_uint(RPC_VERSION)
p.pack_uint(MY_PROGRAM_ID)
p.pack_uint(MY_VERSION_ID)
p.pack_uint(MY_TIME_PROCEDURE_ID)
p.pack_enum(AUTH_NULL)
p.pack_uint(0)
p.pack_enum(AUTH_NULL)
p.pack_uint(0)

print repr(p.get_buffer())

$ python xdrlib-example-2.py
'\000\000\000\001\000\000\000\001\000\000\000\002\000\000\004\322
\000\000\003\350\000\000\'\017\000\000\000\000\000\000\000\000\000
\000\000\000\000\000\000\000'