Java Enterprise Best Practices

Consider Using Byte Arrays to Store Marshalling Results

Marshalling converts an object graph into a set of bytes. The bytes are usually simply pushed into a stream and sent over a wire (or to a file or database). But there’s no reason why another level of indirection can’t be inserted into the process, as in the following code example:

public class SerializeIntoBytes implements Externalizable {
	private byte[] _bytes;
	public void writeExternal(ObjectOutput out) throws IOException {
		if (null == _bytes) {
			createByteArray(  );
		}
		out.writeInt(_bytes.length);
		out.write(_bytes);
	}

	public void readExternal(ObjectInput in) throws IOException, 
ClassNotFoundException {
		int byteArrayLength = in.readInt(  );
		_bytes = new byte[byteArrayLength];
		in.read(_bytes);
		restoreStateFromByteArray(  );
	}

	protected void createByteArray(  )  {
	// The "real" marshalling goes on in here.
	}

	protected void restoreStateFromByteArray(  ) {
	// The "real" demarshalling goes on in here.
	}
}

The first thing this idiom does is enable you to reuse the end result of marshalling an object more than once. Consider, for example, the following scenario:

A client application makes a remote method call to an authentication server and receives an authentication key which will expire in two hours. For the next two hours, whenever the client application makes a call to a back-end server, it passes in the authentication key to prove that it is authorized to make the method call.

The authentication key in this scenario has two crucial features: ...