base64 decoding

There's the #base64 encoding provided with the VW Net Clients, currently in the Protocols-Common package. It's a bit messy to use though, because base64 encoding just doesn't fit very well into the EncodedStream setup. Consequently I'd probably recommend first looking at the Base64 streams that are part of the Postgres-EXDI support. However if you'd rather use something supported by Cincom, in the upcoming VW7.5 we are releasing a new class of DecodedStreams, where base64 encoding fits  better and should be straightforward to use. Here are some examples:

Example - Writing

        | stream input |
        input := ByteArray withAll: (1 to: 32).
        stream := DecodedStream
                                on: String new writeStream
                                encodedBy: B64StreamDecoder asEncoder.
        stream nextPutAll: input.
        stream close.
        stream encodedContents.


Example - Reading

        | stream input |
        input := 'AQIDBAUGBwgJCgsMDQ4PEBESExQVFhcYGRobHB0eHyA='.
        stream := DecodedStream
                                on: input readStream
                                encodedBy: B64StreamDecoder asEncoder.
        stream contents.

If you load a recent version of Protocols-Common from the public repository, you can have it right away.

HTH,

Martin

Sylvain Pralon wrote:

On 23/04/07, Sylvain Pralon <[hidden email]> wrote:
> hello
>
> I work with sockets and one of them returned me a base64 encoded stream.
> I have some problems to decode it.
> Please help me

You can find a portable implementation of Base64 encoding and decoding
streams shipped with the PostgreSQL library.  If you are using a
VisualWorks non-commercial image you'll find it's already loaded.

Browse for references to Base64EncodingReadStream and
Base64EncodingWriteStream for examples of how to read and write Base64
encoded data or even better, load up the Base64Encoding-Tests package
from the public Store and look at the test cases.  But in your case as
you say you have a stream containing Base64 encoded data this should
work:

decodedBytes := (Base64EncodingReadStream onStream: encodedStream) upToEnd.

All the best,
    Bruce
--
Make the most of your skills - with OpenSkills
http://www.openskills.org/

On Apr 23, 2007, at 5:43 PM, Martin Kobetic wrote:

> stream := DecodedStream on: String new writeStream
> encodedBy: B64StreamDecoder asEncoder.


If I may:

What the heck is a B64Stream?
Smalltalk idiom used to be to write that as Base64Stream - what  
happened?


Furthermore we have a class 'Decoder' that is sent #asEncoder.
I would prefer to call such a class an Encoder-Decoder - in our  
vernacular that would be 'Codec'.

        stream := DecodedStream
                        on: String new writeStream
                        encodedBy: Base64Codec asEncoder.





Sorry - can't stand sore eyes ;-)

R
-

Reinout Heeck wrote:
Well, this is somewhat subjective. I personally don't see B64 as such a big deal. On the other hand I can easily imagine someone arguing that only BaseSixtyFourEncoderForDecodedStream is properly intention revealing and the only "true smalltalk way" to name this class. And I'd be ready to strangle him with bare hands every time I saw it :-). Anyway, in reality the name simply evolved to its current form. It started out as a new version of encoder for EncodedStream, and since Base64EncodedStream (including the #base64 symbol) was already taken, I called it B64 at that point. Then DecodedStream came and was clearly a better fit so the encoder got converted for that and it seemed important to emphasize that it is for DecodeStream now, thus the final B64StreamDecoder. I don't have a problem with Base64StreamDecoder or Codec or whatever (as long as there's some level of consistency across the API). In this particular case I could agree that Base64 is better than B64, but I don't t
hink it's such a qualitative jump either. Quick google search confirms that I'm far from being the first one referring to the encoding that way so it definitely shouldn't cause too much confusion.

> Furthermore we have a class 'Decoder' that is sent #asEncoder.
> I would prefer to call such a class an Encoder-Decoder - in our
> vernacular that would be 'Codec'.
>
>     stream := DecodedStream
>             on: String new writeStream
>             encodedBy: Base64Codec asEncoder.

Yes, Decoder asEncoder inside DecodedStream is confusing at best. That's pretty clear at the first sight of the example. There are many possible ways to clean this up and even more loose ends that should be tied up as well.  We're getting there, incrementally. In the mean time using #new instead of #asEncoder should get you through without bodily harm I hope :-).

Cheers,

Martin