GZIP Compression Java/C# difference in compression issue

Question

I\'m adding in compression to my project with the aim of improving speed in the 3G Data communication from Android app to ASP.NET C# Server.

The methods I\'ve resear

Answer 1

I get 42 bytes on .NET as well. I suspect you're using an old version of .NET which had a flaw in its compression scheme.

Here's my test app using your code:

using System;
using System.IO;
using System.IO.Compression;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        var uncompressed = Encoding.UTF8.GetBytes("Mary had a little lamb");
        var compressed = GZIPCompress(uncompressed);
        Console.WriteLine(compressed.Length);
        Console.WriteLine(Convert.ToBase64String(compressed));
    }

    static byte[] GZIPCompress(byte[] data)
    {
        using (var memoryStream = new MemoryStream())
        {
            using (var gZipStream = new GZipStream(memoryStream, 
                                                   CompressionMode.Compress))
            {
                gZipStream.Write(data, 0, data.Length);
            }

            return memoryStream.ToArray();
        }
    }
}

Results:

42
H4sIAAAAAAAEAPNNLKpUyEhMUUhUyMksKclJVchJzE0CAHrIujIWAAAA

This is exactly the same as the Java data.

I'm using .NET 4.5. I suggest you try running the above code on your machine, and compare the results.

I've just decompressed the base64 data you provided, and it is a valid "compressed" form of "Mary had a little lamb", with 22 bytes in the uncompressed data. That surprises me... and reinforces my theory that it's a framework version difference.

EDIT: Okay, this is definitely a framework version difference. If I compile with the .NET 3.5 compiler, then use an app.config which forces it to run with that version of the framework, I see 137 bytes as well. Given comments, it looks like this was only fixed in .NET 4.5.