The xdrlib Module

The xdrlib module converts between Python datatypes and Sun's external data representation (XDR), as Example 4-7 illustrates.

Example 4-7. 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() packed: '0000000100000004spam' unpacked: 1 'spam'

The XDR format is used by Sun's remote procedure call (RPC) protocol. Example 4-8 is an incomplete (and rather contrived) example showing how to build an RPC request package.

Example 4-8. Using the xdrlib Module to Send an 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 a 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()) '000000010000000100000002000004322 0000033500000'17000000000000000000 00000000000000'