SecuritySNACCRuntime/c++-examples/simple/README

   1 (RCS control information is at the end of this file.)
   2
   3
   4 C++ Simple Example README
   5 -------------------------
   6
   7 This directory should have 6 files in it:
   8
   9   README      - this file
  10
  11   genber.C    - C++ source code for a program that creates and encodes
  12                 a PersonnelRecord value to a file.
  13
  14   example.C   - C++ source code for a program that decodes a given
  15                 PersonnelRecord value and re-encodes it to stdout.
  16
  17   makefile    - compiles the example programs
  18
  19   good_pr.ber - BER encoding of a Personnel Record (all definite lengths)
  20
  21
  22
  23 Type "make" to generate the 3 example programs:
  24         genber
  25         def
  26         indef
  27
  28
  29
  30 snacc is called from the makefile on .../asn1specs/p_rec.asn1 to
  31 generate the following files:
  32
  33 p_rec.h  - C++ classes for PersonnelRecord types.
  34
  35 p_rec.C  - C++ source code for the PersonnelRecord encode, decode,
  36            print, and free methods.
  37
  38 These source files are then compiled with example.C to make the
  39 programs def and indef.  Each program takes 1 argument, the name of a
  40 file containing an BER encoded PersonnelRecord value.
  41
  42
  43 Try the following:
  44
  45 %1 genber                       # create a file called pr.ber
  46 %2 indef good_pr.ber > indef_pr.ber
  47 %3 def indef_pr.ber > def_pr.ber
  48 %4 diff good_pr.ber def_pr.ber  # should be no differences
  49
  50 (commands 2-4 can be made via the `check' phony target.)
  51
  52 The above commands decode the BER value in "good_pr.ber" and
  53 indef_pr.ber respectively and then re-encode them to stdout.
  54 Both programs will decode any valid BER representation of a
  55 PersonnelRecord value but, the def program will re-encode the
  56 given data using only the definite length BER format and the
  57 indef program will re-encode the given data using only the
  58 indefinite length BER format.
  59
  60 Compare the lengths of the def_pr.ber and indef_pr.ber files,
  61 indefinite length encodings are usually larger.
  62
  63
  64
  65 Things to Note
  66 --------------
  67
  68 Look at genber.C to see how to build a C++ value and then encode it.
  69 look at the example.C file to see buffer usage.  Look at
  70 .../c++_lib/inc/asn_config.h and .../c++_lib/inc/asn_buf.h if you
  71 want to change the buffer managment.
  72
  73
  74 Snacc ASN.1 comment commands
  75
  76 Notice the special "--snacc" ASN.1 comment in .../asn1specs/p_rec.asn1.
  77
  78 PersonnelRecord ::= --snacc isPdu:"TRUE" -- [APPLICATION 0] IMPLICIT SET
  79  { ... etc. ... }
  80
  81 The "isPdu" flag tells snacc that the PersonnelRecord is a PDU type.
  82 This flag has no effect on the generated C++ code, since each type gets
  83 PDU members automatically for C++.
  84
  85
  86
  87 Length formats
  88
  89 Both the def and indef programs were generated from the same source
  90 file, example.c.  Indefinite length encoders can be created by giving
  91 the -DUSE_INDEF_LEN flag to the C++ compiler when compiling.  Currently
  92 the indefinite/definite length encoder choice is made a compile time.
  93 To change this to a run-time decision, a simple solution would be to
  94 modify BerEncodeConsLen and BerEncodeEocIfNec macros in
  95 .../c++_lib/inc/asn_len.h to check a global flag.
  96
  97 #-------------------------------------------------------------------------------
  98 # $Header: /cvs/root/Security/SecuritySNACCRuntime/c++-examples/simple/Attic/README,v 1.1.1.1 2001/05/18 23:14:05 mb Exp $
  99 # $Log: README,v $
 100 # Revision 1.1.1.1  2001/05/18 23:14:05  mb
 101 # Move from private repository to open source repository
 102 #
 103 # Revision 1.1.1.1  1999/03/16 18:05:57  aram
 104 # Originals from SMIME Free Library.
 105 #
 106 # Revision 1.2  1994/10/08 04:43:46  rj
 107 # the test csh skript has been integrated into the makefile
 108 #
 109 # Revision 1.1  1994/08/31  08:48:05  rj
 110 # first check-in. for a list of changes to the snacc-1.1 distribution please refer to the ChangeLog.
 111 #