Question

I have to load a large xml in flash and I’m trying to send it compressed. To do that I tried to zlib compress the string and send it base64 encoded. In flash I turn the string into a byte array and use its uncompress() method. So far I tried:

ZLIB.NET

byte[] bytData = System.Text.Encoding.UTF8.GetBytes(str);
MemoryStream ms = new MemoryStream();
Stream s = new zlib.ZOutputStream(ms, 3);
s.Write(bytData, 0, bytData.Length);
s.Close();
byte[] compressedData = (byte[])ms.ToArray();
return System.Convert.ToBase64String(compressedData);

Ionic.Zlib (DotNetZip)

return System.Convert.ToBase64String(Ionic.Zlib.GZipStream.CompressBuffer(System.Text.Encoding.UTF8.GetBytes(str)));

ICSharpCode.SharpZipLib (I don’t know how to set the compression to zlib)

byte[] a = Encoding.Default.GetBytes(str);
MemoryStream memStreamIn = new MemoryStream(a);
MemoryStream outputMemStream = new MemoryStream();
ZipOutputStream zipStream = new ZipOutputStream(outputMemStream);
zipStream.SetLevel(3); //0-9, 9 being the highest level of compression
ZipEntry newEntry = new ZipEntry("zipEntryName");
newEntry.DateTime = DateTime.Now;
zipStream.PutNextEntry(newEntry);
StreamUtils.Copy(memStreamIn, zipStream, new byte[4096]);
zipStream.CloseEntry();
zipStream.IsStreamOwner = false; // False stops the Close also Closing the underlying stream.
zipStream.Close(); // Must finish the ZipOutputStream before using outputMemStream.
byte[] byteArrayOut = outputMemStream.ToArray();
return System.Convert.ToBase64String(byteArrayOut);

All produce different results, but flash throws an Error #2058: There was an error decompressing the data.

var decode:ByteArray = Base64.decodeToByteArray(str);
decode.uncompress();
return decode.toString();

Base64 class from here http://code.google.com/p/as3crypto/source/browse/trunk/as3crypto/src/com/hurlant/util/Base64.as?r=3

So, how can i compress a string in .net and decompress it in flash?

Answer 1

I got it to work with ZLIB.NET. I just had to set the encoding to ASCII Encoding.ASCII.GetBytes(str);