Sending object from Android Client App to C# Server App

Question

Java Code:

public class EMessage implements Serializable
{

private Bitmap image;

private String type;

EMessage()

{}

}
...

EMessage eMessage=new EMessage();

outToServer = new DataOutputStream(clientSocket.getOutputStream());

objectOutputStream=new ObjectOutputStream(outToServer);

objectOutputStream.writeObject(eMessage);

C# Code:

[Serializable]

class EMessage

{

    private Bitmap image;

    private String type;

    EMessage()

    { }

}

client = server.AcceptTcpClient();

 Connected = client.Connected;

            ns = client.GetStream();
 IFormatter formatter = new 

 System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();

 EMessage recievedmsg = (EMessage)formatter.Deserialize(ns);

When I send an object from Android Client App (java coded) and I recieve the object in C# Server App but with an Exception. "The Input Stream is not a valid binary format. The Starting Content(in bytes) are: 00-05-73-72-00-1D-63-6F-6D-2E etc"; Please suggest any simple solution. My project isn't that much complex. I just need to send an EMessage object.

Answer 1

Serialization formats are specific to the platforms, and Java and .NET serialization aren't compatible with each other. Use JSON instead (and it's easier to debug as well).

Answer 2

Why not use SOAP, here's an article on exactly what you're doing (android to .net)

http://www.codeproject.com/Articles/29305/Consuming-NET-Web-Services-via-the-kSOAP-library

Answer 3

I suggest you drop the Serialization for the above mentioned reasons (Java serialization being different from C# serialization), and transfer your data between your Java and C# applications in plain byte arrays.

You can convert your Bitmap image to a byte array like so ( taken from this post on SO ):

Bitmap bmp = intent.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();

Of course you could change the CompressFormat if circumstances so require. After that, you could convert your type string to a byte array too, and add a null-terminator to the end of it.

Once you're there, you can send your type string first, and add the byte array of the bitmap after it. On the C# end, you could read the incoming data until you reach the 0 terminator, at which point you'll know you've read the string portion of your EMessage object, and then read the rest of the bytes you've sent over and parse them into a Bitmap object.

That way you'll be sure that between your Java and C# implementations, you won't run into any compatibility issues. It may require a bit more code and a little more understanding to do, but it's far more reliable than serializing between two languages.