Re: Base64 question

Scott,
Maybe I have something wrong in my test code:
I am testing with "ABC"
I translate this to ASCII and get the correct value
X'414243'
I do Base64 encode and get QkJD
Then when I decode it I get X'424243'
Which is BBC

D W$Before S 8A D W$After S 12A D W$AfterLen S 10I 0 * D W$After2 S 12A D W$AfterLen2 S 10I 0 * D P$LEN S 4 0 D P$Table S 10A * C eval W$Before = 'ABC' * Calculate length of PCL commnd string C ' ' CHECKR W$Before P$Len * Convert string to ascii C CALL 'QDCXLATE' C PARM P$len C PARM W$Before C PARM 'QASCII' P$table * * W$Before = 'ABC'; after translation debug shows x'414243'

/free W$AfterLen = B64_Encode( %ADDR(W$Before) : %LEN(%TRIMR(W$Before)) : %ADDR(W$After) : %SIZE(W$After) ); W$AfterLen2 = B64_Decode( %ADDR(W$After) : %LEN(%TRIMR(W$After)) : %ADDR(W$After2) : %SIZE(W$After2) ); *INLR = *ON; /end-free

WAfter2 = debug shows x'424243' (which is BBC)



-----Original Message-----
From: Scott Klement [mailto:midrange-l@xxxxxxxxxxxxxxxx] Sent: Thursday, November 06, 2008 3:13 PM
To: Midrange Systems Technical Discussion
Subject: Re: Base64 question

hi John,

I don't think it makes sense to store in ASCII in the
database. After all, you're likely to want to do other things with your
database besides this one program.

Why not just add code to your RPG program to convert it to
ASCII prior to base64 encoding it?

Here's a trivial example in ILE RPG, that uses the
IBM-supplied QDCXLATE program to convert from EBCDIC to ASCII:

D QDCXLATE PR
ExtPgm('QDCXLATE')
D Len 5p 0 const
D data 32702a
options(*varsize)
D table 10a const

D data s 5
/free
data = 'Hello';
QDCXLATE( %len(data)
: data
: 'QTCPASC' );

The above method is really easy to do, and it works. It can
be used with any of the translation tables (*TBL objects) on your system.
QTCPASC is an IBM-supplied table that translates to ASCII.

There are two big problems with QDCXLATE:

a) You can't use it to translate a single-byte character set
to a double or mixed-byte character set.

b) In order to make it work properly with variant
characters, you have to find (or create) a table that translates exactly the way
you want. (there are many versions of ASCII and many versions of
EBCDIC. Which one are you translating from? Which one are you translating
to?)

A more sophisticated method of doing the translation (and
one that requires more code) is to use the iconv() API. With iconv()
you can provide the exact from/to CCSID and it'll translate between
them. It also lets you work with double-byte and multi-byte character
sets. But the code is more complex, so I'll leave you with the
QDCXLATE API for now, and if you find that lacking, let me know and I'll post
an iconv example.

But, at any rate, ASCII/EBCDIC translation is hardly part of
Base64 encoding! Indeed, most of the time you use base64 encoding
expressly because your data isn't text data!



John Allen wrote:

1)If I have the value "Hello" in my database field on the
System i (in EBCDIC) isn't there some method I can convert
it to an ASCII value before encoding it to Base64 so I end
up with the correct Base64 value the ASCII machine is
expecting, or just store it in my database field in ASCII
format (although it is actually an EBCDIC System)?
Example If the value were 123 in EBCDIC it would be stored
as x'F1F2F3' Could I store it as ASCII x'313233' then

could

it be encoded to Base64 to be read in correctly by ASCII
system?